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Ethnopharmacological Relevance: Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine that is composed of 12 crude drugs. It has been used in the treatment of diabetic neuropathic pain (DNP) for more than 30 years., Aim of Study: Microglia are thought to play an important role in neuropathic pain. This study aimed to evaluate the protective effect of JMT against DNP and to investigate the underlying mechanisms in which the microglia and JAK2/STAT3 signaling pathway were mainly involved., Materials and Methods: The chemical composition of JMT was analyzed using liquid chromatography tandem mass spectrometry. The diabetes model was constructed using 11 to 12-week-old male Zucker diabetic fatty (ZDF) rat (fa/fa). The model rats were divided into 5 groups and were given JMT at three dosages (11.6, 23.2, and 46.4 g/kg, respectively, calculated as the crude drug materials), JAK inhibitor AG490 (positive drug, 10 μg/day), and placebo (deionized water), respectively, for eight weeks (n = 6). Meanwhile, Zucker lean controls (fa/+) were given a placebo (n = 6). Body weight was tested weekly and blood glucose was monitored every 2 weeks. The mechanical allodynia and heat hyperalgesia were assessed using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests. After treatment, the microglia activation marker Iba-1, CD11B, CD68, neuroinflammatory mediators, and mediators of the JAK2/STAT3 signaling pathway were compared between different groups. The mRNA and protein levels of target genes were assessed by quantitative real-time PCR and Western Blot, respectively., Results: We found that JMT significantly inhibited the overactivation of microglia in spinal cords, and suppressed neuroinflammation of DNP model rats, thereby ameliorating neurological dysfunction and injuries. Furthermore, these effects of JMT could be attributed to the inhibition of the JAK2/STAT3 signaling pathway., Conclusions: Our findings suggested that JMT effectively ameliorated DNP by modulating microglia activation via inhibition of the JAK2/STAT3 signaling pathway. The present study provided a basis for further research on the therapeutic strategies of DNP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Several reports, including our previous studies, indicate that hyperglycemia and diabetes mellitus exert differential effects on vascular function in males and females. This study examines sex differences in the vascular effects of type 2 diabetes (T2D) in an established monogenic model of obesity-induced T2D, Zucker Diabetic Fatty (ZDF) rats. Acetylcholine (ACh) responses were assessed in phenylephrine pre-contracted rings before and after apocynin, a NADPH oxidase (NOX) inhibitor. The mRNA expressions of aortic endothelial NOS (eNOS), and key NOX isoforms were also measured. We demonstrated the following: (1) diabetes had contrasting effects on aortic vasorelaxation in ZDF rats, impairing relaxation to ACh in females while enhancing it in male ZDF rats; (2) inhibition of NOX, a major source of superoxide in vasculature, restored aortic vasorelaxation in female ZDF rats; and (3) eNOS and NOX4 mRNA expressions were elevated in female (but not male) ZDF rat aortas compared to their respective leans. This study highlights sexual dimorphism in ACh-mediated vasorelaxation in the aorta of ZDF rats, suggesting that superoxide may play a role in the impaired vasorelaxation observed in female ZDF rats.

Diabetic kidney disease (DKD) remains as one of the leading long-term complications of type 2 diabetic mellitus (T2DM). Studies have shown that decreased expression of glucose-6-phosphate dehydrogenase (G6PD) plays an important role in DKD. However, the upstream and downstream pathways of G6PD downregulation leading to DKD have not been elucidated. We conducted a series of studies including clinical study, animal studies, and in vitro studies to explore this. First, a total of 90 subjects were evaluated including 30 healthy subjects, 30 patients with T2DM, and 30 patients with DKD. The urinary G6PD activity and its association with the clinical markers were analyzed. Multivariate linear regression analysis was used to analyze the risk factors of urinary G6PD in these patients. Then, microRNAs that were differentially expressed in urine and could bind and degrade G6PD were screened and verified in patients with DKD. After that, high glucose (HG)-cultured human kidney cells (HK-2) and Zucker diabetic fatty (ZDF) rats were used to test the roles of miR-7977/G6PD/albumin-induced autophagy in DKD. Beclin and P62 were used as markers of kidney autophagy indicators. A dual-luciferase reporter assay system was used to test the binding of G6PD by mir-7977. The plasma and urinary G6PD activity were decreased significantly in patients with DKD, accompanied by increased urinary mir-7977 level. The fasting plasma glucose (FPG), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and urinary albumin excretion were independent predictors of urinary G6PD activity, according to multiple linear regression analysis. The increased expression of miR-7977 and decreased expression of G6PD were also found in the kidney of ZDF rats with early renal tubular damage. The correlation analysis showed that beclin protein expression levels were positively correlated with kidney G6PD activity, whereas P62 protein expression was negatively correlated with kidney G6PD activity in rats. In HK-2 cells cultured with normal situation, a low level of albumin could induce autophagy along with the stimulation of G6PD, although this was impaired under high glucose. Overexpression of G6PD reversed albumin-induced autophagy in HK-2 cells under high glucose. Further study revealed that G6PD was a downstream target of miR-7977. Inhibition of miR-7977 expression led to significantly increased expression of G6PD and reversed the effects of high glucose on albumin-induced autophagy. In conclusion, our study supports a new mechanism of G6PD downregulation in DKD. Therapeutic measures targeting the miR-7977/G6PD/autophagy signaling pathway may help in the prevention and treatment of DKD. NEW & NOTEWORTHY This study provides new evidence that reduced glucose-6-phosphate dehydrogenase (G6PD) may damage the endocytosis of renal tubular epithelial cells by reducing albumin-induced autophagy. More importantly, for the first time, our study has provided evidence from humans that the decrease in urinary G6PD activity is positively associated with renal injury, and abnormal glucose and lipid metabolism may be important reasons for reduced G6PD levels. Increased miR-7977 may at least in part explain the downregulation of G6PD.

The metabolic syndrome is characterized by obesity, insulin resistance, dyslipidemia and hypertension and predisposes to cardiorenal injury. Here, we tested our hypothesis that 8-aminoguanine, an endogenous purine, exerts beneficial effects in Zucker Diabetic-Sprague Dawley (ZDSD) rats, a preclinical model of the metabolic syndrome. ZDSD rats were instrumented for blood pressure radiotelemetry and randomized to vehicle or 8-aminoguanine (10 mg/kg/day, po). The protocol was divided into four phases: Phase 1: 17 days of tap water/normal diet; Phase 2: 30 days of 1% saline/normal diet; Phase 3: 28 days of 1% saline/diabetogenic diet; Phase 4: acute/terminal measurements. 8-Aminoguanine: (1) decreased mean arterial blood pressure (P = 0.0004; 119.5 ± 1.0 (vehicle) versus 116.3 ± 1.0 (treated) mmHg) throughout all three phases of the radiotelemetry study; (2) rebalanced the purine metabolome away from hypoxanthine (pro-inflammatory) and towards inosine (anti-inflammatory); (3) reduced by 71% circulating IL-1β, a cytokine that contributes to hypertension-induced adverse cardiovascular events and type 2 diabetes; (4) attenuated renovascular responses to angiotensin II; (5) improved cardiac and renal histopathology; (6) attenuated diet-induced polydipsia/polyuria; and (7) reduced HbA1c. In the metabolic syndrome, 8-aminoguanine lowers blood pressure, improves diabetes and reduces organ damage, likely by rebalancing the purine metabolome leading to reductions in injurious cytokines such as IL-1β., (© 2024. The Author(s).)

The liver and kidneys are crucial for glucose homeostasis and are seriously damaged in diabetes. Cocoa and carob possess antidiabetic activity, but their hepatorenal protective effects, especially when combined with antidiabetic drugs, are unknown. The aim of this study is to investigate the effects of a cocoa-carob-supplemented diet (CC), either alone or in combination with metformin, on liver and kidney damage in Zucker diabetic fatty (ZDF) rats, a type 2 diabetes model. Male ZDF animals received a control or CC-supplemented diet, with or without metformin, and Zucker lean rats were fed the control diet. The CC-supplemented diet improved glucose tolerance and insulin resistance and alleviated functional and structural alterations in the diabetic liver and renal cortex. The CC-supplemented diet also ameliorated oxidative stress, downregulated apoptosis, and improved insulin signalling and glucose homeostasis. The combination of CC and metformin boosted several benefits as certain parameters related to morphological and structural alterations, apoptosis, oxidative stress, glucose homeostasis, and insulin resistance, were improved in comparison to animals receiving the CC-supplemented diet or metformin alone; these include the following: apoptotic index, Bax, hepatic insulin receptor or glutathione content, among others. These results demonstrate that the CC-supplemented diet alleviates the hepatorenal damage in type 2 diabetic ZDF rats, highlighting its potential alone or as an adjuvant therapy.

Obesity and diabetes are major risk factors for cardiovascular diseases. Zucker fatty diabetes mellitus (ZFDM) rats are novel animal model of obesity and type 2 diabetes. We have recently reported that blood pressure in ZFDM-Lepr fa/fa (Homo) rats was normal, while blood adrenaline level and heart rate were lower than those in control ZFDM-Lepr fa/+ (Hetero) rats. Here, we compared the reactivity in isolated mesenteric artery between Hetero and Homo rats. Contraction induced by phenylephrine was increased, while relaxation induced by isoprenaline was decreased in Homo rats at 21-23 weeks old compared with those in Hetero rats. The mRNA expression for α 1A but not β 2 adrenoreceptor in Homo rats was increased. Nitric oxide (NO)-mediated relaxation induced by acetylcholine was decreased, while the mRNA expression for endothelial NO synthase (eNOS) was rather increased in mesenteric artery from Homo rats. These findings for the first time revealed that in Homo rats with reduced plasma adrenaline, blood pressure could be maintained by enhancing vascular contractility induced by adrenaline through the increased α 1 adrenoceptor expression and the attenuated β 2 adrenoceptor signaling. Additionally, NO-mediated endothelium-dependent relaxation is impaired perhaps due to eNOS dysfunction, which might also contribute to maintain the blood pressure in Homo rats., Competing Interests: Declaration of competing interest The authors have no potential conflicts of interest., (Copyright © 2024 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Introduction: Sleeve gastrectomy (SG), results in improvement in hypertension. We have previously published that rodent SG improves hypertension independent of weight loss associated with unique shifts in the gut microbiome. We tested if the gut microbiome directly improves blood pressure by performing fecal material transfer (FMT) from post-SG rats to surgery-naïve animals., Methods: We performed SG or Sham surgery in male, Zucker rats (n = 6-7) with obesity. Stool was collected postop from surgical donors for treatment of recipient rats. Three nonsurgical groups received daily, oral consumption of SG stool, sham stool, or vehicle alone (Nutella) for 10 wk (n = 7-8). FMT treatment was assessed for effects on body weight, food intake, oral glucose tolerance, and blood pressure. Genomic deoxyribonucleic acid of stool from donor and recipient groups were sequenced by 16S ribosomal ribonucleic acid and analyzed for diversity, abundance, and importance., Results: Ten weeks of SG-FMT treatment significantly lowered systolic blood pressures in surgery-naïve, recipient rats compared to vehicle treatment alone (126.8 ± 13.3 mmHg versus 151.8 ± 12.2 mmHg, P = 0.001). SG-FMT treatment also significantly altered beta diversity metrics compared to Sham-FMT and vehicle treatment. In random forest analysis, amplicon sequence variant level significantly predicted FMT group, P = 0.01., Conclusions: We have found a direct link between gut microbial changes after SG and regulation of blood pressure. Future mechanistic studies are required to learn what specific gut microbial changes are required to induce improvements in obesity-associated hypertension and translation to clinical, metabolic surgery., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The mechanisms responsible for glomerular hemodynamic regulation with sodium-glucose co-transporter 2 (SGLT2) inhibitors in kidney disease due to type 2 diabetes remain unclear. Therefore, we investigated changes in glomerular hemodynamic function using an animal model of type 2 diabetes, treated with an SGLT2 inhibitor alone or in combination with a renin-angiotensin-aldosterone system inhibitor using male Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats. Afferent and efferent arteriolar diameter and single-nephron glomerular filtration rate (SNGFR) were evaluated in ZDF rats measured at 0, 30, 60, 90, and 120 minutes after the administration of a SGLT2 inhibitor (luseogliflozin). Additionally, we assessed these changes under the administration of the adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine), along with coadministration of luseogliflozin and an angiotensin II receptor blocker (ARB), telmisartan. ZDF rats had significantly increased SNGFR, and afferent and efferent arteriolar diameters compared to ZL rats, indicating glomerular hyperfiltration. Administration of luseogliflozin significantly reduced afferent vasodilatation and glomerular hyperfiltration, with no impact on efferent arteriolar diameter. Urinary adenosine levels were increased significantly in the SGLT2 inhibitor group compared to the vehicle group. A1aR antagonism blocked the effect of luseogliflozin on kidney function. Co-administration of the SGLT2 inhibitor and ARB decreased the abnormal expansion of glomerular afferent arterioles, whereas the efferent arteriolar diameter was not affected. Thus, regulation of afferent arteriolar vascular tone via the A1aR pathway is associated with glomerular hyperfiltration in type 2 diabetic kidney disease., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Activation of pyruvate dehydrogenase (PDH) by inhibition of pyruvate dehydrogenase kinase (PDHK) has the potential for the treatment of diabetes mellitus and its complications, caused by the malfunction of the glycolytic system and glucose oxidation. In this paper, we describe the identification of novel PDHK inhibitors with a fluorene structure. High-throughput screening using our in-house library provided compound 6 as a weak inhibitor that occupied the allosteric lipoyl group binding site in PDHK2. Structure-based drug design (SBDD) while addressing physicochemical properties succeeded in boosting inhibitory activity approximately 700-fold. Thus obtained compound 32 showed favorable pharmacokinetics profiles supported by high membrane permeability and metabolic stability, and exhibited activation of PDH in rat livers and a glucose lowering effect in Zucker fatty rats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Liver transplantation remains the only definitive treatment for end-stage liver diseases. However, the increasing prevalence of fatty liver disease among potential donors exacerbates the shortage of suitable organs. This study evaluates the efficacy of the preservation solution Institut Georges Lopez-2 (IGL-2) compared to Histidine-Tryptophan-Ketoglutarate (HTK) and University of Wisconsin (UW) preservation solutions in mitigating ischemia-reperfusion injury (IRI) in steatotic livers. Using Zucker Obese rat livers, we assessed the impact of 24-h static cold storage (SCS) with each solution on transaminase release, glutathione redox balance, antioxidant enzyme activity, lipoperoxidation, and inflammation markers. IGL-2 and UW solutions demonstrated reduced transaminase and lactate levels compared to HTK, indicating better preservation of liver integrity. IGL-2 maintained a higher reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, suggesting more effective management of oxidative stress. Antioxidant enzyme activities catalase, superoxide dismutase, and glutathione peroxidase (CAT, SOD, GPX) were higher in IGL-2 preserved livers, contributing to decreased oxidative damage. Lipid peroxidation markers and inflammatory markers were lower in IGL-2 than in HTK, indicating reduced oxidative stress and inflammation. Additionally, improved mitochondrial function was observed in the IGL-2 group, correlating with reduced reactive oxygen species (ROS) production and lipid peroxidation. These findings suggest that IGL-2 offers superior preservation of liver viability, reduces oxidative stress, and minimizes inflammation compared to HTK and UW solutions. By maintaining a higher ratio of reduced glutathione and antioxidant enzyme activity, IGL-2 effectively mitigates the harmful effects of ischemia-reperfusion injury. The reduced lipid peroxidation and inflammation in the IGL-2 group further underscore its potential in improving liver transplant outcomes. These results highlight the importance of optimizing preservation solutions to enhance the viability and functionality of donor organs, potentially expanding the donor pool and improving the success rates of liver transplantation. Future research should focus on refining preservation techniques and exploring additional protective agents to further improve organ preservation and transplant outcomes.

Objective: This study aims to investigate the mechanisms underlying the impaired healing response by diabetes after periodontal therapy., Background: Outcomes of periodontal therapy in patients with diabetes are impaired compared with those in patients without diabetes. However, the mechanisms underlying impaired healing response to periodontal therapy have not been sufficiently investigated., Materials and Methods: Zucker diabetic fatty (ZDF) and lean (ZL) rats underwent experimental periodontitis by ligating the mandibular molars for one week. The gingiva at the ligated sites was harvested one day after ligature removal, and gene expression was comprehensively analyzed using RNA-Seq. In patients with and without type 2 diabetes (T2D), the corresponding gene expression was quantified in the gingiva of the shallow sulcus and residual periodontal pocket after non-surgical periodontal therapy., Results: Ligation-induced bone resorption and its recovery after ligature removal were significantly impaired in the ZDF group than in the ZL group. The RNA-Seq analysis revealed 252 differentially expressed genes. Pathway analysis demonstrated the enrichment of downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway. PPARα and PPARγ were decreased in mRNA level and immunohistochemistry in the ZDF group than in the ZL group. In clinical, probing depth reduction was significantly less in the T2D group than control. Significantly downregulated expression of PPARα and PPARγ were detected in the residual periodontal pocket of the T2D group compared with those of the control group, but not in the shallow sulcus between the groups., Conclusions: Downregulated PPAR subtypes expression may involve the impaired healing of periodontal tissues by diabetes., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Long-acting dual amylin and calcitonin receptor agonists (DACRAs) are novel candidates for the treatment of type 2 diabetes and obesity due to their beneficial effects on body weight, glucose control, and insulin action. However, how the metabolic benefits are maintained after long-lasting treatment is unknown. This study investigates the long-term anti-obesity and anti-diabetic treatment efficacy of the DACRA KBP-336 alone and combined with the GLP-1 analog semaglutide. Zucker diabetic Sprague Dawley (ZDSD) rats with obesity and diabetes received KBP-336 (4.5 nmol/kg Q3D), semaglutide (50 nmol/kg Q3D), or the combination for 7 mo, and the treatment impact on body weight, food intake, glucose control, and insulin action was evaluated. Furthermore, serum levels of the cardiac fibrosis biomarker endotrophin were evaluated. KBP-336, semaglutide, and the combination lowered body weight significantly compared with the vehicle, with the combination inducing a larger and more sustained weight loss than either monotherapy. All treatments resulted in reduced fasting blood glucose levels and HbA1c levels and improved glucose tolerance compared with vehicle-treated rats. Furthermore, all treatments protected against lost insulin secretory capacity and improved insulin action. Serum levels of endotrophin were significantly lowered by KBP-336 compared with vehicle. This study shows the benefit of combining KBP-336 and semaglutide to obtain significant and sustained weight loss, as well as improved glucose control. Furthermore, KBP-336-driven reductions in circulating endotrophin indicate a clear reduction in the risk of complications. Altogether, KBP-336 is a promising candidate for the treatment of obesity and type 2 diabetes both alone and in combination with GLP-1 analogs. NEW & NOTEWORTHY These studies describe the benefit of combining dual amylin and calcitonin receptor agonists (DACRA) with semaglutide for long-term treatment of obesity and type 2 diabetes. Combination treatment induced sustained weight loss and improved glucose control. A DACRA-driven reduction in a serological biomarker of cardiac fibrosis indicated a reduced risk of complications. These results highlight DACRAs as a promising candidate for combination treatment of obesity and type 2 diabetes and related long-term complications.

Aims: Bariatric surgery results in rapid recovery of glucose control in subjects with type 2 diabetes mellitus. However, the underlying mechanisms are still largely unknown. The present study aims to clarify how bariatric surgery modifies pancreatic cell subgroup differentiation and transformation in the single-cell RNA level., Methods: Male, 8-week-old Zucker diabetic fatty (ZDF) rats with obesity and diabetes phenotypes were randomized into sleeve gastrectomy (Sleeve, n = 9), Roux-en-Y gastric bypass (RYGB, n = 9), and Sham (n = 7) groups. Two weeks after surgery, the pancreas specimen was further analyzed using single-cell RNA-sequencing technique., Results: Two weeks after surgery, compared to the Sham group, the metabolic parameters including fasting plasma glucose, plasma insulin, and oral glucose tolerance test values were dramatically improved after RYGB and Sleeve procedures (p < .05) as predicted. In addition, RYGB and Sleeve groups increased the proportion of pancreatic β cells and reduced the ratio of α cells. Two multiple hormone-expressing cells were identified, the Gcg+/Ppy + and Ins+/Gcg+/Ppy + cells. The pancreatic Ins+/Gcg+/Ppy + cells were defined for the first time, and further investigation indicates similarities with α and β cells, with unique gene expression patterns, which implies that pancreatic cell transdifferentiation occurs following bariatric surgery., Conclusions: For the first time, using the single-cell transcriptome map of ZDF rats, we reported a comprehensive characterization of the heterogeneity and differentiation of pancreatic endocrinal cells after bariatric surgery, which may contribute to the underlying mechanisms. Further studies will be needed to elucidate these results., (© 2024 The Author(s). Journal of Diabetes published by Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.)

Background: Dihydrogen (H 2 ) is produced endogenously by the intestinal microbiota through the fermentation of diet carbohydrates. Over the past few years, numerous studies have demonstrated the significant therapeutic potential of H 2 in various pathophysiological contexts, making the characterization of its production in laboratory species of major preclinical importance., Methods: This study proposes an innovative solution to accurately monitor H 2 production in free-moving rodents while respecting animal welfare standards. The developed device consisted of a wire rodent cage placed inside an airtight chamber in which the air quality was maintained, and the H 2 concentration was continuously analyzed. After the airtightness and efficiency of the systems used to control and maintain air quality in the chamber were checked, tests were carried out on rats and mice with different metabolic phenotypes, over 12 min to 1-h experiments and repeatedly. H 2 production rates (HPR) were obtained using an easy calculation algorithm based on a first-order moving average., Results: HPR in hyperphagic Zucker rats was found to be twice as high as in control Wistar rats, respectively, 2.64 and 1.27 nmol.s -1 per animal. In addition, the ingestion of inulin, a dietary fiber, stimulated H 2 production in mice. HPRs were 0.46 nmol.s -1 for animals under control diet and 1.99 nmol.s -1 for animals under inulin diet., Conclusions: The proposed device coupled with our algorithm enables fine analysis of the metabolic phenotype of laboratory rats or mice with regard to their endogenous H 2 production., (© 2024 The Author(s). Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

Background: Physical activity has profound benefits on health, especially in patients with cardiovascular and metabolic disease. Exercise training can reduce oxidative stress, improve renal function, and thus lower blood pressure. However, the effect of exercise training on angiotensin II type 1 receptors (AT 1 R) and endothelin subtype B receptors (ETBR)-mediated diuresis and natriuresis in obese Zucker rats is unclear., Methods: Lean and obese Zucker rats were exercised or placed on a nonmoving treadmill for 8 weeks. Blood pressure was measured by tail-cuff plethysmography, and functions of AT 1 R and ETBR in the kidney were measured by natriuresis, respectively., Results: Our data showed that exercise training improved glucose and lipid metabolism, renal function and sodium excretion in obese Zucker rats, accompanied by decreased oxidative stress and GRK4 expression in obese Zucker rats. Moreover, exercise training reduced the Candesartan-induced an increase in diuresis and natriuresis and increased ETBR agonists (BQ3020)-mediated diuresis and natriuresis in obese Zucker rats, which were associated with decreased renal AT 1 R expression and ETBR phosphorylation levels., Conclusions: The results demonstrate that exercise training lowers blood pressure via improving renal AT 1 R and ETBR function through modulating GRK4 expression in Obese Zucker Rats and provides potentially effective targets for obesity-related hypertension.

Purpose: Alpelisib plus fulvestrant demonstrated a significant progression-free survival benefit versus fulvestrant in patients with PIK3CA-mutated HR+ /HER2- advanced breast cancer (ABC) (SOLAR-1). Hyperglycemia, an on-target adverse effect of PI3Kα inhibition, can lead to dose modifications, potentially impacting alpelisib efficacy. We report data from preclinical models and two clinical trials (SOLAR-1 and BYLieve) on Sodium glucose cotransporter 2 inhibitor (SGLT2i) use to improve PI3Kα inhibitor-associated hyperglycemia., Methods: Healthy Brown Norway (BN), mild diabetic Zucker diabetic fatty (ZDF), and Rat1-myr-p110α/HBRX3077 tumor-bearing nude rats treated with alpelisib were analyzed for glucose and insulin control with metformin and dapagliflozin (SGLT2i) and alpelisib efficacy. Hyperglycemia adverse events (AEs) were compared between patients receiving SGLT2i with alpelisib (n = 19) and a propensity score-matched cohort not receiving SGLT2i (n = 74) in both trials., Results: Dapagliflozin and metformin in BN and ZDF rats treated with alpelisib normalized blood glucose and reduced insulin levels. No signs of ketosis or drug-drug interaction were observed when metformin and dapagliflozin was administered with alpelisib. Alpelisib antitumor efficacy was maintained when used with dapagliflozin in tumor-bearing rats. Compared with a matched set of patients without SGLT2i, patients receiving SGLT2i had 4.9 and 6.4 times lower rates of grade ≥ 3 hyperglycemia AEs and hyperglycemia AEs resulting in alpelisib dose adjustments, interruptions, or withdrawals, respectively, and a relative reduction in risk of experiencing these AEs (70.6% and 35.7%)., Conclusion: These data suggest adding an SGLT2i can effectively manage hyperglycemia, resulting in fewer alpelisib dose modifications and discontinuations in patients with PIK3CA-mutated HR+ /HER2- ABC (SOLAR-1: NCT02437318; BYLieve: NCT03056755)., (© 2024. The Author(s).)

Background and Purpose: Sodium glucose cotransporter 2 inhibitors (SGLT2i) have emerged as a potent therapy for heart failure with preserved ejection fraction (HFpEF). Hydrogen sulphide (H 2 S), a well-studied cardioprotective agent, could be beneficial in HFpEF. SGLT2i monotherapy and combination therapy involving an SGLT2i and H 2 S donor in two preclinical models of cardiometabolic HFpEF was investigated., Experimental Approach: Nine-week-old C57BL/6N mice received L-NAME and a 60% high fat diet for five weeks. Mice were then randomized to either control, SGLT2i monotherapy or SGLT2i and H 2 S donor, SG1002, for five additional weeks. Ten-week-old ZSF1 obese rats were randomized to control, SGLT2i or SGLT2i and SG1002 for 8 weeks. SG1002 monotherapy was investigated in additional animals. Cardiac function (echocardiography and haemodynamics), exercise capacity, glucose handling and multiorgan pathology were monitored during experimental protocols., Key Results: SGLT2i treatment improved E/e' ratio and treadmill exercise in both models. Combination therapy afforded increases in cardiovascular sulphur bioavailability that coincided with improved left end-diastolic function (E/e' ratio), exercise capacity, metabolic state, cardiorenal fibrosis, and hepatic steatosis. Follow-up studies with SG1002 monotherapy revealed improvements in diastolic function, exercise capacity and multiorgan histopathology., Conclusions and Implications: SGLT2i monotherapy remediated pathological complications exhibited by two well-established HFpEF models. Adjunctive H 2 S therapy resulted in further improvements of cardiometabolic perturbations beyond SGLT2i monotherapy. Follow-up SG1002 monotherapy studies inferred an improved phenotype with combination therapy beyond either monotherapy. These data demonstrate the differing effects of SGLT2i and H 2 S therapy while also revealing the superior efficacy of the combination therapy in cardiometabolic HFpEF., (© 2024 The Author(s). British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Background: The prevention of obesity represents a major health and socio-economic challenge. Nutraceuticals are regularly highlighted for their beneficial effects in preventing the metabolic disturbances associated with obesity. However, few studies have described the combined action of nutraceutical mixtures combining polyphenols with alkaloids., Objective: The aim of this study was to evaluate the effects of long-term dietary supplementation with a mixture of Berberine, Citrus and Apple extracts (BCA) in the primary prevention of obesity and its metabolic and vascular complications in the obese Zucker rat, a spontaneous model of genetic obesity and insulin resistance., Methods: Sixteen 8-week-old obese Zucker male rats were randomly divided into two groups: all rats received oral gavage daily either with water, untreated obese (U-ObZ) or BCA (BCA-ObZ) mixture for thirteen weeks. Morphological and metabolic parameters were measured along the study. Cumulative concentration-response curves to insulin, acetylcholine and phenylephrine were determined on isolated thoracic aorta. Colon permeability measurements were performed using the Ussing chamber technique. Fecal samples collected at the beginning and the end of the protocol were used as a template for amplification of the V3-V4 region of the 16S rDNA genes., Results: BCA supplementation reduced weight gain (p<0.05) and food intake (p<0.05) in the BCA-ObZ group rats compared to the U-ObZ group rats. It also improved glucose tolerance (p<0.001) and decreased fasting insulin and Homeostasis model assessment index (p<0.05). Through ex vivo experiments, the BCA mixture enhanced significantly aortic insulin relaxation (p<0.01), reduced α1-adrenoceptor-mediated vasoconstriction (p<0.01), and decreased distal colon permeability. Moreover, short-chain fatty acid producers such as Bacteroides, Blautia, and Akkermansia were found to be increased by the BCA mixture supplementation., Conclusion: The results showed that a 13-week-supplementation with BCA mixture prevented weight gain and improved glucose metabolism in obese Zucker rats. We also demonstrated that BCA supplementation improved vascular function, colonic barrier permeability and gut microbiota profile., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Siliman Misha et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Little is known about the adaptor protein FAM159B. To determine whether FAM159B expression findings in rats or mice can be extrapolated to humans, we compared FAM159B expression in healthy tissue samples from all three species using immunohistochemistry. Despite variations in expression intensity, similar FAM159B expression patterns were observed in most organs across species. The most prominent species difference was noted in pancreatic islets; while FAM159B expression was limited to single cells on the outer edges in mice and rats, it was detectable across entire islets in humans. Double-labeling immunohistochemistry revealed partial overlap of FAM159B expression with that of insulin, glucagon, and somatostatin in human islets. By contrast, FAM159B showed complete colocalization with only somatostatin in rats and mice. An additional analysis of FAM159B expression in lean and obese Zucker rats revealed larger islet areas due to increased β-cell mass in obese rats, which was accompanied by a smaller percentage of FAM159B-positive δ-cells per islet area. Beyond the known differences in islet architecture across species, our results point to larger dissimilarities in blood glucose regulation between rodents and humans than generally assumed. Moreover, findings regarding FAM159B expression (and function) cannot be directly transferred between rodents and humans., Competing Interests: Competing InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

We aimed to investigate the therapeutic potential of ibuprofen against type 2 diabetes (T2D) using obese Zucker diabetic fatty (ZDF) rats as type 2 diabetes model. ZDF rats were hyperglycemic, dyslipidemic and expressed proinflammatory markers in contrast to lean controls, thus reflecting the relationship between obesity and chronic inflammation promoting T2D. Chronic treatment with ibuprofen (2-(4-Isobutylphenyl)propanoic acid) was used to study the impact on pathological T2D conditions as compared to metformin (1,1-dimethylbiguanide) treated ZDF as well as lean controls. Ibuprofen decreased A1c but induced a high insulin release with improved glucose tolerance only after early time points (i.g., 15 and 30 min) resulting in a non-significant decline of AUC values and translating into a high HOMA-IR. In addition, ibuprofen significantly lowered cholesterol, free fatty acids and HDL-C. Some of these effects by ibuprofen might be based on its anti-inflammatory effects through inhibition of cytokine/chemokine signaling (i.g., COX-2, ICAM-1 and TNF-α) as measured in whole blood and epididymal adipose tissue by TaqMan and/or upregulation of anti-inflammatory cytokines (i.g., IL-4 and IL-13) by ELISA analysis in blood. In conclusion, our ZDF animal study showed positive effects of ibuprofen against diabetic complications such as inflammation and dyslipidemia but also demonstrated the risk of causing insulin resistance.

Type 2 diabetes mellitus (T2DM) increases the risk of non-alcoholic fatty liver disease (NAFLD) progression to advanced stages, especially upon high-fat diet (HFD). HFD-induced hepatic fibrosis can be marked by oxidative stress, inflammation, and activation of hepatic stellate cells. Sirtuin 1/2 (SIRT1/2), NAD-dependent class III histone deacetylases, are involved in attenuation of fibrosis. In our conducted research, TGF-β1-activated LX-2 cells, free fatty acid (FFA)-treated simultaneous co-culture (SCC) cells, and HFD-induced hepatic fibrosis in Zucker diabetic fatty (ZDF) rats, a widely used animal model in the study of metabolic syndromes, were used to evaluate the protective effect of Tenovin-1, a SIRT1/2 inhibitor. ZDF rats were divided into chow diet, HFD, and HFD + Tenovin-1 groups. Tenovin-1 reduced hepatic damage, inhibited inflammatory cell infiltration, micro/ macro-vesicular steatosis and prevented collagen deposition HFD-fed rats. Tenovin-1 reduced serum biochemical parameters, triglyceride (TG) and malondialdehyde (MDA) levels but increased glutathione, catalase, and superoxide dismutase levels. Tenovin-1 mitigated proinflammatory cytokines IL-6, IL-1β, TNFα and fibrosis biomarkers in HFD rats, TGF-β1-activated LX-2 and FFA treated SCC cells. Additionally, Tenovin-1 suppressed SIRT1/2 expression and inhibited JNK-1 and STAT3 phosphorylation in HFD rats and FFA-treated SCC cells. In conclusion, Tenovin-1 attenuates hepatic fibrosis by stimulating antioxidants and inhibiting inflammatory cytokines under HFD conditions in diabetic rats., Competing Interests: Competing Interests: The authors declare that they have no competing financial interests or personal relationships that may have influenced the work reported in this study., (© The author(s).)

Zinc deficiency has been associated with the worsening of diabetes while zinc supplementation has been proposed to ameliorate diabetes. This study examined the effects of marginal zinc deficiency (MZD) and zinc supplementation (ZS) on obesity, glycemic control, pancreatic islets, hepatic steatosis and renal function of Zucker diabetic fatty (ZDF) rats. Male ZDF rats were fed an MZD, zinc control (ZC) or ZS diet (4, 30 and 300 mg Zn/kg diet, respectively), and lean Zucker rats were fed a ZC diet for 8 weeks. MZD and ZS did not alter body weight or whole-body composition in ZDF rats. MZD ZDF rats had reduced zinc concentrations in the femur and pancreas, a greater number of enlarged pancreatic islets and a diminished response to an oral glucose load based on a 1.8-fold greater incremental area-under-the-curve (AUC) for glucose compared to ZC ZDF. ZS ZDF rats had elevated serum, femur and pancreatic zinc concentrations, unchanged pancreatic parameters and a 50% reduction in the AUC for insulin compared to ZC ZDF rats, suggesting greater insulin sensitivity. Dietary zinc intake did not alter hepatic steatosis, creatinine clearance, or levels of proteins that contribute to insulin signaling, inflammation or zinc transport in epididymal fat. Potential adverse effects of ZS were suggested by reduced hepatic copper concentrations and elevated serum urea compared to ZC ZDF rats. In summary, ZS improved the pancreatic insulin response but not the glucose handling. In contrast, reduced zinc status in ZDF rats led to impaired glucose tolerance and a compensatory increase in the number and size of pancreatic islets which could lead to β-cell exhaustion.

Phosphodiesterase (PDE) inhibitors - such as vardenafil - are used primarily for treating erectile dysfunction via increasing cyclic guanosine monophosphate (cGMP) levels. Recent studies have also demonstrated their significant cardioprotective effects in several diseases, including diabetes, upon long-term, continuous application. However, PDE inhibitors are not specific for PDE5 and also inhibit the retinal isoform. A sustained rise in cGMP in photoreceptors is known to be toxic; therefore, we hypothesized that long-term vardenafil treatment might result in retinotoxicity. The hypothesis was tested in a clinically relevant animal model of type 2 diabetes mellitus. Histological experiments were performed on lean and diabetic Zucker Diabetic Fatty rats. Half of the animals were treated with vardenafil for six months, and the retinal effects were evaluated. Vardenafil treatment alleviated rod outer segment degeneration but decreased rod numbers in some positions and induced changes in the interphotoreceptor matrix, even in control animals. Vardenafil treatment decreased total retinal thickness in the control and diabetic groups and reduced the number of nuclei in the outer nuclear layer. Müller cell activation was detectable even in the vardenafil-treated control animals, and vardenafil did not improve gliosis in the diabetic group. Vardenafil-treated animals showed complex retinal alterations with improvements in some parameters while deterioration in others. Our results point towards the retinotoxicity of vardenafil, even without diabetes, which raises doubts about the retinal safety of long-term continuous vardenafil administration. This effect needs to be considered when approving PDE inhibitors for alternative indications., Competing Interests: Declaration of competing interest G.M.S. has received speaker and consultant honoraria from Allergan, Bayer, Novartis, Roche and Carl Zeiss Meditec. All other authors (K.Sz., B.D., A.É., R.I.H., L.K.L., A. Sz., T.R., Cs.M., A.O., K.A.K., Á.Sz. and Á.L.) declare no potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Clinical studies demonstrated beneficial effects of sodium-glucose-transporter 2 inhibitors on the risk of cardiovascular death in patients with heart failure with preserved ejection fraction (HFpEF). However, underlying processes for cardioprotection remain unclear. The present study focused on the impact of empagliflozin (Empa) on myocardial function in a rat model with established HFpEF and analyzed underlying molecular mechanisms., Methods: Obese ZSF1 (Zucker fatty and spontaneously hypertensive) rats were randomized to standard care (HFpEF, n=18) or Empa (HFpEF/Empa, n=18). ZSF1 lean rats (con, n=18) served as healthy controls. Echocardiography was performed at baseline and after 4 and 8 weeks, respectively. After 8 weeks of treatment, hemodynamics were measured invasively, mitochondrial function was assessed and myocardial tissue was collected for either molecular and histological analyses or transmission electron microscopy., Results: In HFpEF Empa significantly improved diastolic function (E/é: con: 17.5±2.8; HFpEF: 24.4±4.6; P <0.001 versus con; HFpEF/Empa: 19.4±3.2; P <0.001 versus HFpEF). This was accompanied by improved hemodynamics and calcium handling and by reduced inflammation, hypertrophy, and fibrosis. Proteomic analysis demonstrated major changes in proteins involved in mitochondrial oxidative phosphorylation. Cardiac mitochondrial respiration was significantly impaired in HFpEF but restored by Empa (V max complex IV: con: 0.18±0.07 mmol O 2 /s/mg; HFpEF: 0.13±0.05 mmol O 2 /s/mg; P <0.041 versus con; HFpEF/Empa: 0.21±0.05 mmol O 2 /s/mg; P =0.012 versus HFpEF) without alterations of mitochondrial content. The expression of cardiolipin, an essential stability/functionality-mediating phospholipid of the respiratory chain, was significantly decreased in HFpEF but reverted by Empa (con: 15.9±1.7 nmol/mg protein; HFpEF: 12.5±1.8 nmol/mg protein; P =0.002 versus con; HFpEF/Empa: 14.5±1.8 nmol/mg protein; P =0.03 versus HFpEF). Transmission electron microscopy revealed a reduced size of mitochondria in HFpEF, which was restored by Empa., Conclusions: The study demonstrates beneficial effects of Empa on diastolic function, hemodynamics, inflammation, and cardiac remodeling in a rat model of HFpEF. These effects were mediated by improved mitochondrial respiratory capacity due to modulated cardiolipin and improved calcium handling., Competing Interests: Disclosures Dr Winzer reports personal fees from Amarin, Amgen, AstraZeneca, Daiichi Sankyo, Bayer, Boehringer Ingelheim, CVRx, and Novartis for lectures and advisory board activities outside the submitted work. Dr Linke reports grants from Novartis, personal fees from Medtronic, Abbott, Edwards Lifesciences, Boston Scientific, AstraZeneca, Novartis, Pfizer, Abiomed, Bayer, Boehringer, and other from Picardia, Transverse Medical, Claret Medical, outside the submitted work. The other authors report no conflicts.

Background: Depression is a common psychiatric disorder in diabetic patients. Depressive mood associated with obesity/metabolic disorders is related to the inflammatory response caused by long-term consumption of high-fat diets, but its molecular mechanism is unclear. In this study, we investigated whether the antidepressant effect of transcutaneous auricular vagus nerve stimulation (taVNS) in high-fat diet rats works through the P2X7R/NLRP3/IL-1β pathway., Methods: We first used 16S rRNA gene sequencing analysis and LC-MS metabolomics assays in Zucker diabetic fatty (ZDF) rats with long-term high-fat diet (Purina #5008) induced significant depression-like behaviors. Next, the forced swimming test (FST) and open field test (OFT) were measured to evaluate the antidepressive effect of taVNS. Immunofluorescence and western blotting (WB) were used to measure the microglia state and the expression of P2X7R, NLRP3, and IL-1β in PFC., Results: Purina#5008 diet induced significant depression-like behaviors in ZDF rats and was closely related to purine and inflammatory metabolites. Consecutive taVNS increased plasma insulin concentration, reduced glycated hemoglobin and glucagon content in ZDF rats, significantly improved the depressive-like phenotype in ZDF rats through reducing the microglia activity, and increased the expression of P2X7R, NLRP3, and IL-1β in the prefrontal cortex (PFC)., Conclusion: The P2X7R/NLRP3/IL-1β signaling pathway may play an important role in the antidepressant-like behavior of taVNS, which provides a promising mechanism for taVNS clinical treatment of diabetes combined with depression., (© 2024 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Aims: Part of hypothalamic (mediobasal hypothalamus [MBH]) neurons detect changes in blood glucose levels that in turn coordinate the vagal control of insulin secretion. This control cascade requires the production of mitochondrial reactive oxygen species (mROS), which is altered in models of obesity and insulin resistance. Obese, insulin-resistant Zücker rats are characterized by hypothalamic hypersensitivity to glucose. This initiates an abnormal vagus-induced insulin secretion, associated with an overproduction of mROS in response to a low glucose dose. Here, we hypothesized that ghrelin, known to buffer reactive oxygen species (ROS) via mitochondrial function, may be a major component of the hypothalamic glucose hypersensitivity in the hypoghrelinemic obese Zücker rat. Results: Hypothalamic glucose hypersensitivity-induced insulin secretion of Zücker obese rats was reversed by ghrelin pretreatment. The overproduction of MBH mROS in response to a low glucose load no longer occurred in obese rats that had previously received the cerebral ghrelin infusion. This decrease in mROS production was accompanied by a normalization of oxidative phosphorylation (OXPHOS). Conversely, blocking the action of ghrelin with a growth hormone secretagogue receptor antagonist in a model of hyperghrelinemia (fasted rats) completely restored hypothalamic glucose sensing-induced insulin secretion that was almost absent in this physiological situation. Accordingly, ROS signaling and mitochondrial activity were increased by the ghrelin receptor antagonist. Innovation: These results demonstrate for the first time that ghrelin addressed only to the brain could have a protective effect on the defective control of insulin secretion in the insulin-resistant, hypoghrelinemic obese subject. Conclusions: Ghrelin, through its action on OXPHOS, modulates mROS signaling in response to cerebral hyperglycemia and the consequent vagal control of insulin secretion. In insulin-resistant obese states, brain hypoghrelinemia could be responsible for the nervous defect in insulin secretion.

Polyunsaturated fatty acids (PUFAs) can alter adipose tissue function; however, the relative effects of plant and marine n3-PUFAs are less clear. Our objective was to directly compare the n3-PUFAs, plant-based α-linolenic acid (ALA) in flaxseed oil, and marine-based eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in high-purity oils versus n6-PUFA containing linoleic acid (LA) for their effects on the adipose tissue and oral glucose tolerance of obese rats. Male fa / fa Zucker rats were assigned to faALA, faEPA, faDHA, and faLA groups and compared to baseline fa / fa rats (faBASE) and lean Zucker rats (lnLA). After 8 weeks, faEPA and faDHA had 11-14% lower body weight than faLA. The oral glucose tolerance and total body fat were unchanged, but faEPA had less mesenteric fat. faEPA and faDHA had fewer large adipocytes compared to faLA and faALA. EPA reduced macrophages in the adipose tissue of fa / fa rats compared to ALA and DHA, while faLA had the greatest macrophage infiltration. DHA decreased (~10-fold) T-cell infiltration compared to faBASE and faEPA, whereas faALA and faLA had an ~40% increase. The n3-PUFA diets attenuated tumour necrosis factor-α in adipose tissue compared to faBASE, while it was increased by LA in both genotypes. In conclusion, EPA and DHA target different aspects of inflammation in adipose tissue.

Type 2 diabetes mellitus (T2DM) is one of the world's principal metabolic diseases characterized by chronic hyperglycemia. The gut incretin hormones, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP), which has been proposed as a new treatment for T2DM, are extensively metabolized by Dipeptidyl peptidase 4 (DPP-4). Inhibitors of DPP-4 block the degradation of GLP-1 and GIP and may increase their natural circulating levels, favoring glycemic control in T2DM. A novel and potent selective inhibitor of DPP-4 with an 8-purine derived structure ( 1 ) has been developed and tested in vitro and in vivo in Zücker obese diabetic fatty (ZDF) rats, an experimental model of the metabolic syndrome and T2DM to assess the inhibitory activity using vildagliptin as reference standard. ZDF rats were subdivided into three groups (n = 7/group), control (C-ZDF), and those treated with compound 1 (Compound 1 -ZDF) and with vildagliptin (V-ZDF), both at 10 mg/kg/d rat body weight, in their drinking water for 12 weeks, and a group of lean littermates (ZL) was used. ZDF rats developed DM (fasting hyperglycemia, 425 ± 14.8 mg/dL; chronic hyperglycemia, HbA1c 8.5 ± 0.4%), compared to ZL rats. Compound 1 and vildagliptin reduced sustained HbAl1c (14% and 10.6%, P < 0.05, respectively) and fasting hyperglycemia values (24% and 19%, P < 0.05, respectively) compared to C-ZDF group (P < 0.001). Compound 1 and vildagliptin have shown a potent activity with an IC 50 value of 4.92 and 3.21 µM, respectively. These data demonstrate that oral compound 1 administration improves diabetes in ZDF rats by the inhibitory effect on DPP-4, and the potential to be a novel, efficient and tolerable approach for treating diabetes of obesity-related T2DM, in ZDF rats., Competing Interests: The authors report no conflicts of interest in this work., (© 2024 Chayah et al.)

Metabolic syndrome (MetS) is associated with development of tauopathies that contribute to cognitive decline. Without functional leptin receptors, male obese Zucker rats (OZRs) develop MetS, and they have increased phosphorylated tau (ptau) with impaired cognitive function. In addition to regulating energy balance, leptin enhances activation of the hippocampus, which is essential for spatial learning and memory. Whether spatial learning and memory are always impaired in OZRs or develop with MetS is unknown. We hypothesized that male OZRs develop MetS traits that promote regional increases in ptau and functional deficits associated with those brain regions. In the medulla and cortex, tau-pSer 199,202 and tau-pSer 396 were comparable in juvenile (7-8 wk old) lean Zucker rats (LZRs) and OZRs but increased in 18- to 19-wk-old OZRs. Elevated tau-pSer 396 was concentrated in the dorsal vagal complex of the medulla, and by this age OZRs had hypertension with increased arterial pressure variability. In the hippocampus, tau-pSer 199,202 and tau-pSer 396 were still comparable in 18- to 19-wk-old OZRs and LZRs but elevated in 28- to 29-wk-old OZRs, with emergence of deficits in Morris water maze performance. Comparable escape latencies observed during acquisition in 18- to 19-wk-old OZRs and LZRs were increased in 28- to 29-wk-old OZRs, with greater use of nonspatial search strategies. Increased ptau developed with changes in the insulin/phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in the hippocampus and cortex but not medulla, suggesting different underlying mechanisms. These data demonstrate that leptin is not required for spatial learning and memory in male OZRs. Furthermore, early development of MetS-associated autonomic dysfunction by the medulla may be predictive of later hippocampal dysfunction and cognitive impairment. NEW & NOTEWORTHY Male obese Zucker rats (OZRs) lack functional leptin receptors and develop metabolic syndrome (MetS). At 16-19 wk, OZRs are insulin resistant, with increased ptau in dorsal medulla and impaired autonomic regulation of AP. At 28-29 wk OZRs develop increased ptau in hippocampus with deficits in spatial learning and memory. Juvenile OZRs lack elevated ptau and these deficits, demonstrating that leptin is not essential for normal function. Elevated ptau and deficits emerge before the onset of diabetes in insulin-resistant OZRs.

Dietary soy protein and soy isoflavones have anti-inflammatory properties. Previously, we reported that feeding soy protein concentrate diet (SPC) with low or high isoflavone (LIF or HIF) to young (seven-week-old) obese (fa/fa) Zucker rats inhibits lipopolysaccharide (LPS) translocation and decreases liver inflammation compared to a casein control (CAS) diet. The current study investigated whether SPC-LIF and SPC-HIF diets would reduce liver inflammation in adult obese Zucker rats fed a CAS diet. A total of 21 six-week-old male obese (fa/fa) Zucker rats were given CAS diet for 8 weeks to develop obesity then randomly assigned to CAS, SPC-LIF, or SPC-HIF (seven rats/group) diet for an additional 10 weeks. The expression of LPS-translocation, inflammation, and intestinal permeability markers were quantified by qPCR in liver, visceral adipose tissue (VAT), and colon. LPS concentration was determined in both the colon content and fecal samples by a Limulus amebocyte lysate (LAL) test. SPC-LIF and SPC-HIF diets significantly decreased liver LPS-binding protein (LBP) expression compared to CAS diet ( p < 0.01 and p < 0.05, respectively). SPC-HIF diet also significantly decreased liver MCP-1 and TNF-α expression ( p < 0.05) and had a trend to decrease liver iNOS expression ( p = 0.06). In the colon, SPC-HIF diet significantly increased LBP expression compared to CAS diet ( p < 0.05). When samples from all three groups were combined, there was a negative correlation between colon LBP expression and liver LBP expression ( p = 0.046). SPC diets did not alter the expression of intestinal permeability markers (i.e., occludin, claudin 3, and zonula occludens-1) in the colon or inflammation markers (i.e., TNF-α and iNOS) in VAT or the colon. LPS levels in the colon content did not differ between any groups. Fecal LPS levels were significantly higher in the SPC-LIF and SPC-HIF groups compared to the CAS group ( p < 0.01). In conclusion, SPC, particularly SPC with HIF, reduces liver LBP expression and inflammation makers (i.e., TNF-α and MCP-1 expression) in adult obese Zucker rats, likely by reducing LPS translocation.

Long-chain n -3 PUFA (LC n -3 PUFA) prevent, in rodents, insulin resistance (IR) induced by a high-fat and/or fructose diet but not IR induced by glucocorticoids. In humans, contrasting effects have also been reported. We investigated their effects on insulin sensitivity, feed intake (FI) and body weight gain in genetically insulin resistant male obese (fa/fa) Zucker (ZO) rats during the development of obesity. ZO rats were fed a diet supplemented with 7 % fish oil (FO) + 1 % corn oil (CO) (wt/wt) (ZO FO ), while the control group was fed a diet containing 8 % fat from CO (wt/wt) (ZO CO ). Male lean Zucker (ZL) rats fed either FO (ZL FO ) or CO (ZL CO ) diet were used as controls. FO was a marine-derived TAG oil containing EPA 90 mg/g + DHA 430 mg/g. During an oral glucose tolerance test, glucose tolerance remained unaltered by FO while insulin response was reduced in ZO FO only. Liver insulin sensitivity (euglycaemic-hyperinsulinaemic clamp + 2 deoxyglucose) was improved in ZO FO rats, linked to changes in phosphoenolpyruvate carboxykinase expression, activity and glucose-6-phosphatase activity. FI in response to intra-carotid insulin/glucose infusion was decreased similarly in ZO FO and ZO CO . Hypothalamic ceramides levels were lower in ZO FO than in ZO CO . Our study demonstrates that LC n -3 PUFA can minimise weight gain, possibly by alleviating hypothalamic lipotoxicity, and liver IR in genetically obese Zucker rats.

Melatonin acute treatment limits obesity of young Zücker diabetic fatty (ZDF) rats by non-shivering thermogenesis (NST). We recently showed melatonin chronically increases the oxidative status of vastus lateralis (VL) in both obese and lean adult male animals. The identification of VL skeletal muscle-based NST by uncoupling of sarcoendoplasmic reticulum Ca 2+ -ATPase (SERCA)- sarcolipin (SLN) prompted us to investigate whether melatonin is a SERCA-SLN calcium futile cycle uncoupling and mitochondrial biogenesis enhancer. Obese ZDF rats and lean littermates (ZL) of both sexes were subdivided into two subgroups: control (C) and 12 weeks orally melatonin treated (M) (10 mg/kg/day). Compared to the control groups, melatonin decreased the body weight gain and visceral fat in ZDF rats of both sexes. Melatonin treatment in both sex obese rats restored the VL muscle skin temperature and sensitized the thermogenic effect of acute cold exposure. Moreover, melatonin not only raised SLN protein levels in the VL of obese and lean rats of both sexes; also, the SERCA activity. Melatonin treatment increased the SERCA2 expression in obese and lean rats (both sexes), with no effects on SERCA1 expression. Melatonin increased the expression of thermogenic genes and proteins (PGC1-α, PPARγ, and NRF1). Furthermore, melatonin treatment enhanced the expression ratio of P-CaMKII/CaMKII and P-AMPK/AMPK. In addition, it rose mitochondrial biogenesis. These results provided the initial evidence that chronic oral melatonin treatment triggers the CaMKII/AMPK/PGC1α axis by upregulating SERCA2-SLN-mediated NST in ZDF diabetic rats of both sexes. This may further contribute to the body weight control and metabolic benefits of melatonin., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Hyperglucagonemia is a hallmark of type 2 diabetes (T2DM), yet the role of elevated plasma glucagon (P-GCG) to promote excessive postabsorptive glucose production and contribute to hyperglycemia in patients with this disease remains debatable. We investigated the acute action of P-GCG to safeguard/support postabsorptive endogenous glucose production (EGP) and euglycemia in healthy Zucker control lean (ZCL) rats. Using male Zucker diabetic fatty (ZDF) rats that exhibit the typical metabolic disorders of human T2DM, such as excessive EGP, hyperglycemia, hyperinsulinemia, and hyperglucagonemia, we examined the ability of hyperglucagonemia to promote greater rates of postabsorptive EGP and hyperglycemia. Euglycemic or hyperglycemic basal insulin (INS-BC) and glucagon (GCG-BC) clamps were performed in the absence or during an acute setting of glucagon deficiency (GCG-DF, ∼10% of basal), either alone or in combination with insulin deficiency (INS-DF, ∼10% of basal). Glucose appearance, disappearance, and cycling rates were measured using [2- 3 H] and [3- 3 H]-glucose. In ZCL rats, GCG-DF reduced the levels of hepatic cyclic AMP, EGP, and plasma glucose (PG) by 50%, 32%, and 50%, respectively. EGP fell in the presence GCG-DF and INS-BC, but under GCG-DF and INS-DF, EGP and PG increased two- and threefold, respectively. GCG-DF revealed the hyperglucagonemia present in ZDF rats lacked the ability to regulate hepatic intracellular cyclic AMP levels and glucose flux, since EGP and PG levels fell by only 10%. We conclude that the liver in T2DM suffers from resistance to all three major regulatory factors, glucagon, insulin, and glucose, thus leading to a loss of metabolic flexibility. NEW & NOTEWORTHY In postabsorptive state, basal plasma insulin (P-INS) and plasma glucose (PG) act dominantly to increase hepatic glucose cycling and reduce endogenous glucose production (EGP) and PG in healthy rats, which is only counteracted by the acute action of basal plasma glucagon (P-GCG) to support EGP and euglycemia. Hyperglucagonemia, a hallmark of type 2 diabetes (T2DM) present in Zucker diabetic fatty (ZDF) rats, is not the primary mediator of hyperglycemia and high EGP as commonly thought; instead, the liver is resistant to glucagon as well as insulin and glucose.

Purpose: Type 2 diabetes mellitus (T2DM) is associated with a greater risk of Alzheimer's disease. Synaptic impairment and protein aggregates have been reported in the brains of T2DM models. Here, we assessed whether neurodegenerative changes in synaptic vesicle 2 A (SV2A), γ-aminobutyric acid type A (GABA A ) receptor, amyloid-β, tau and receptor for advanced glycosylation end product (RAGE) can be detected in vivo in T2DM rats., Methods: Positron emission tomography (PET) using [ 18 F]SDM-8 (SV2A), [ 18 F]flumazenil (GABA A receptor), [ 18 F]florbetapir (amyloid-β), [ 18 F]PM-PBB3 (tau), and [ 18 F]FPS-ZM1 (RAGE) was carried out in 12-month-old diabetic Zucker diabetic fatty (ZDF) and SpragueDawley (SD) rats. Immunofluorescence staining, Thioflavin S staining, proteomic profiling and pathway analysis were performed on the brain tissues of ZDF and SD rats., Results: Reduced cortical [ 18 F]SDM-8 uptake and cortical and hippocampal [ 18 F]flumazenil uptake were observed in 12-month-old ZDF rats compared to SD rats. The regional uptake of [ 18 F]florbetapir and [ 18 F]PM-PBB3 was comparable in the brains of 12-month-old ZDF and SD rats. Immunofluorescence staining revealed Thioflavin S-negative, phospho-tau-positive inclusions in the cortex and hypothalamus in the brains of ZDF rats and the absence of amyloid-beta deposits. The level of GABA A receptors was lower in the cortex of ZDF rats than SD rats. Proteomic analysis further demonstrated that, compared with SD rats, synaptic-related proteins and pathways were downregulated in the hippocampus of ZDF rats., Conclusion: These findings provide in vivo evidence for regional reductions in SV2A and GABA A receptor levels in the brains of aged T2DM ZDF rats., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Achieving surgical success in orthopedic patients with metabolic disease remains a substantial challenge. Diabetic patients exhibit a unique tissue microenvironment consisting of high levels of reactive oxygen species (ROS), which promotes osteoclastic activity and leads to decreased bone healing. Alternative solutions, such as synthetic grafts, incorporating progenitor cells or growth factors, can be costly and have processing constraints. Previously, the potential for thiol-methacrylate networks to sequester ROS while possessing tunable mechanical properties and degradation rates has been demonstrated. In this study, the ability to fabricate thiol-methacrylate interconnected porous scaffolds using emulsion templating to create monoliths with an average porosity of 97.0% is reported. The average pore sizes of the scaffolds range from 27 to 656 µm. The scaffolds can sequester pathologic levels of ROS via hydrogen peroxide consumption and are not impacted by sterilization. Subcutaneous implantation shows no signs of acute toxicity. Finally, in a 6-week bilateral calvarial defect model in Zucker diabetic fatty rats, ROS scaffolds increase new bone volume by 66% over sham defects. Histologic analysis identifies woven bone infiltration throughout the scaffold and neovascularization. Overall, this study suggests that porous thiol-methacrylate scaffolds may improve healing for bone grafting applications where high levels of ROS hinder bone growth., (© 2023 The Authors. Macromolecular Bioscience published by Wiley-VCH GmbH.)

Background: Palm oil (PO) is the most widely utilized plant oil for food production. Owing to the great ecologic problems associated with PO production, sustainably produced fats, such as insect fat, might be a suitable alternative., Objectives: The hypothesis was tested that fat from Hermetia illucens larvae (HF) compared with PO and soybean oil (SO) has no adverse effects on hepatic lipid metabolism, plasma metabolome, and cecal microbiome in obese Zucker rats., Methods: Thirty male obese Zucker rats were randomly assigned to 3 groups (SO, PO, HF; n = 10 rats/group) and fed 3 different semisynthetic diets containing either SO, PO, or HF as the main fat source for 4 wk. The effects were evaluated by measurement of liver and plasma lipid concentrations, liver transcriptomics, targeted plasma metabolomics, and cecal microbiomics., Results: Supplementation of HF reduced hepatic triglyceride concentration and messenger ribonucleic acid concentrations of selected genes involved in fatty acid and triglyceride synthesis in comparison to PO (P < 0.05). Pairwise comparison of the Simpson index and Jaccard index showed a higher cecal microbial α- and β-diversity in rats fed the HF diet than in rats fed the PO diet (P = 0.015 and P = 0.027), but no difference between rats fed the diets with SO or PO. Taxonomic analysis of the cecal microbial community revealed a lower abundance of Clostridium&#95;sensu&#95;stricto&#95;1 and a higher abundance of Blautia, Mucispirillum, Anaerotruncus, Harryflintia, and Peptococcus in rats supplemented with HF than in rats supplemented with PO (P < 0.05)., Conclusions: HF, compared with PO, has liver lipid-lowering effects in obese Zucker rats, which may be caused by a shift in the gut microbial community. Thus, HF might serve as a sustainably produced fat alternative to PO for food production., Competing Interests: Conflict of interest The authors report no conflicts of interest., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Background: Idiopathic intracranial hypertension (IIH) is a syndrome exhibiting elevated intracranial pressure (ICP), visual disturbances, and severe headache. IIH primarily affects young obese women, though it can occur in individuals of any age, BMI, and sex. IIH is characterized by systemic metabolic dysregulation with a profile of increased androgen hormones. However, the contribution of obesity/hormonal perturbations to cerebrospinal fluid (CSF) dynamics remains unresolved., Methods: We employed obese female Zucker rats and adjuvant testosterone to reveal IIH causal drivers. ICP and CSF dynamics were determined with in vivo experimentation and magnetic resonance imaging, testosterone levels assessed with mass spectrometry, and choroid plexus function revealed with transcriptomics., Results: Obese rats had undisturbed CSF testosterone levels and no changes in ICP or CSF dynamics. Adjuvant testosterone treatment of obese rats elevated the CSF secretion rate, although with no effect on the ICP, due to elevated CSF drainage capacity of these rats., Conclusions: Obesity in itself therefore does not suffice to recapitulate the IIH symptoms in rats, but modulation of CSF dynamics appears with adjuvant testosterone treatment, which mimics the androgen excess observed in female IIH patients. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH and could potentially serve as a future therapeutic target., (© 2024. The Author(s).)

Recent studies have implicated pre-beta and beta lipoproteins (VLDL and LDL) in the etiopathogenesis of complications of diabetes mellitus (DM). In contrast, alpha lipoprotein (HDL) is protective of the beta cells of the pancreas. This study examined the distribution of HDL in the islets of Langerhans of murine models of type 1 diabetic rats (streptozotocin (STZ)-induced DM in Wistar rats) and type 2 models of DM rats (Goto-Kakizaki (GK), non-diabetic Zucker lean (ZL), and Zucker diabetic and fatty (ZDF)). The extent by which HDL co-localizes with insulin or glucagon in the islets of the pancreas was also investigated. Pancreatic tissues of Wistar non-diabetic, diabetic Wistar, GK, ZL, and ZDF rats were processed for immunohistochemistry. Pancreatic samples of GK rats fed with either a low-fat or a high-fat diet were prepared for transmission immune-electron microscopy (TIEM) to establish the cytoplasmic localization of HDL in islet cells. HDL was detected in the core and periphery of pancreatic islets of Wistar non-diabetic and diabetic, GK, ZL, and ZDF rats. The average total of islet cells immune positive for HDL was markedly (<0.05) reduced in GK and ZDF rats in comparison to Wistar controls. The number of islet cells containing HDL was also remarkably ( p < 0.05) reduced in Wistar diabetic rats and GK models fed on high-fat food. The co-localization study using immunofluorescence and TIEM techniques showed that HDL is detected alongside insulin within the secretory granules of β-cells. HDL did not co-localize with glucagon. This observation implies that HDL may contribute to the metabolism of insulin.

The loss of functional beta-cell mass in diabetes is directly linked to the development of diabetic complications. Although dietary flavonoids have demonstrated antidiabetic properties, their potential effects on pancreatic beta-cell preservation and their synergistic benefits with antidiabetic drugs remain underexplored. We have developed a potential functional food enriched in flavonoids by combining cocoa powder and carob flour (CCB), which has shown antidiabetic effects. Here, we investigated the ability of the CCB, alone or in combination with metformin, to preserve pancreatic beta cells in an established diabetic context and their potential synergistic effect. Zucker diabetic fatty rats (ZDF) were fed a CCB-rich diet or a control diet, with or without metformin, for 12 weeks. Markers of pancreatic oxidative stress and inflammation, as well as relative beta-cell mass and beta-cell apoptosis, were analyzed. Results demonstrated that CCB feeding counteracted pancreatic oxidative stress by enhancing the antioxidant defense and reducing reactive oxygen species. Moreover, the CCB suppressed islet inflammation by preventing macrophage infiltration into islets and overproduction of pro-inflammatory cytokines, along with the inactivation of nuclear factor kappa B (NFκB). As a result, the CCB supplementation prevented beta-cell apoptosis and the loss of beta cells in ZDF diabetic animals. The observed additive effect when combining the CCB with metformin underscores its potential as an adjuvant therapy to delay the progression of type 2 diabetes.

Background and Objectives: Diabetes and especially insulin resistance are associated with an increased risk of developing cognitive dysfunction, making anti-diabetic drugs an interesting therapeutic option for the treatment of neurodegenerative disorders. Dual amylin and calcitonin receptor agonists (DACRAs) elicit beneficial effects on glycemic control and insulin sensitivity. However, whether DACRAs affect cognition is unknown., Design and Intervention: Zucker Diabetic Fatty rats were treated with either the DACRA KBP-336 (4.5 nmol/kg Q3D), the amylin analog AM1213 (25 nmol/kg QD), or vehicle for 18 weeks. Further, the efficacy of a late KBP-336 intervention was evaluated by including a group starting treatment on day 30. Glucose control and tolerance were evaluated throughout the study and spatial learning and memory were evaluated by Morris Water Maze after 17 weeks of treatment., Results: When evaluating spatial learning, rats receiving KBP-336 throughout the study performed significantly better than AM1213, vehicle, and late intervention KBP-336. Both KBP-336 and AM1213 treatments improved spatial memory compared to the vehicle. The overall performance in the cognitive tests was reflected in the treatment efficacy on glycemic control, where KBP-336 was superior to AM1213., Conclusion: In summary, the DACRA KBP-336 ameliorates diabetes-induced spatial learning and memory impairment in diabetic rats. Further, KBP-336 improves long-term glycemic control superior to the amylin analog AM1213. Taken together, KBP-336 is, due to its anti-diabetic and insulin-sensitizing properties, a promising candidate for the treatment of cognitive impairments., Competing Interests: MAK and KH own stock in Nordic Bioscience A/S. All authors are employed by Nordic Bioscience A/S

Chronic inflammation and insulin resistance lead to metabolic syndrome and there is an urgent need to establish effective treatments and prevention methods. Our previous study reported that obese model Zucker (fa/fa) rats fed with ozonated olive oil alleviated fatty liver and liver damage by suppressing inflammatory factors. However, differences among animal species related to the safety and efficacy of ozonated olive oil administration remain unclear. Therefore, this study investigated the effects of oral intake of ozonated olive oil on lipid metabolism in normal mice and mice in the obesity model. C57BL/6J and db/db mice were fed the following AIN-76 diets for four weeks: the mice were either fed a 0.5% olive oil diet (Control diet) or 0.5% ozonated olive oil diet (Oz-Olive diet) in addition to 6.5% corn oil. The results indicated that four weeks of Oz-Olive intake did not adversely affect growth parameters, hepatic lipids or serum parameters in normal C57BL/6J mice. Subsequent treatment of db/db mice with Oz-Olive for four weeks reduced the levels of hepatic triglycerides, serum alkaline phosphatase, and serum insulin. These effects of Oz-Olive administration might be due to suppression of fatty acid synthesis activity and expression of lipogenic genes, as well as suppression of inflammatory gene expression. In conclusion, this study confirmed the safety of Oz-Olive administration in normal mice and its ability to alleviate hepatic steatosis by inhibiting fatty acid synthesis and inflammation in obese mice.

Vulnerable patients are at risk for neuroinflammation-mediated post-operative complications, including depression (POD) and cognitive dysfunction (POCD). Zucker rats, expressing multiple risk factors for post-operative complications in humans, may provide a clinically relevant model to study pathophysiology and explore potential interventions. J147, a newly developed anti-dementia drug, was shown to prevent POCD in young healthy rats, and improved early post-surgical recovery in Zucker rats. Aim of the present study was to investigate POCD and the therapeutic potential of J147 in male Zucker rats. Risk factors in the Zucker rat strain were evaluated by comparison with lean littermates. Zucker rats were subjected to major abdominal surgery. Acute J147 treatment was provided by a single iv injection (10 mg/kg) at the start of surgery, while chronic J147 treatment was provided in the food (aimed at 30 mg/kg/day), starting one week before surgery and up to end of protocol. Effects on behavior were assessed, and plasma, urine and brain tissue were collected and processed for immunohistochemistry and molecular analyses. Indeed, Zucker rats displayed increased risk factors for POCD, including obesity, high plasma triglycerides, low grade systemic inflammation, impaired spatial learning and decreased neurogenesis. Surgery in Zucker rats reduced exploration and increased anxiety in the Open Field test, impaired short-term spatial memory, induced a shift in circadian rhythm and increased plasma neutrophil gelatinase-associated lipocalin (NGAL), microglia activity in the CA1 and blood brain barrier leakage. Chronic, but not acute J147 treatment reduced anxiety in the Open Field test and protected against the spatial memory decline. Moreover, chronic J147 increased glucose sensitivity. Acute J147 treatment improved long-term spatial memory and reversed the circadian rhythm shift. No anti-inflammatory effects were seen for J147. Although Zucker rats displayed risk factors, surgery did not induce extensive POCD. However, increased anxiety may indicate POD. Treatment with J147 showed positive effects on behavioral and metabolic parameters, but did not affect (neuro)inflammation. The mixed effect of acute and chronic treatment may suggest a combination for optimal treatment., Competing Interests: Declaration of Competing Interest All authors have no competing interest to declare., (Copyright © 2023. Published by Elsevier Inc.)

Aims: The objective of this study was to characterize the pharmacokinetics (PK)/pharmacodynamics (PD) of DWP16001, a novel sodium-glucose cotransporter 2 inhibitor, and predict efficacious doses for the first-in-human study using various translational approaches., Methods: A mechanistic PK/PD model was developed for DWP16001 using nonlinear mixed-effect modelling to describe animal PK/PD properties. Using allometry and in silico physiologically based equations, human PK parameters were predicted. Human PD parameters were scaled by applying interspecies difference and in vitro drug-specific factors. Human parameters were refined using early clinical data. Model-predicted PK and PD outcomes were compared to observations before and after parameter refinement., Results: The PK/PD model of DWP16001 was developed using a 2-compartment model with first-order absorption and indirect response. Efficacious doses of 0.3 and 2 mg of DWP16001 were predicted using human half-maximal inhibitory concentration values translated from Zucker Diabetic Fatty rats and normal rats, respectively. After parameter refinement, doses of 0.2 and 1 mg were predicted to be efficacious for each disease model, which improved the prediction results to within a 1.2-fold difference between the model prediction and observation., Conclusions: This study predicted efficacious human doses of DWP16001 using population PK/PD modelling and a combined translational pharmacometrics approach. Early clinical data allowed the methods used to translate in vitro and in vivo findings to clinical PK/PD values for DWP16001 to be optimized. This study has shown that a refinement step can be readily applied to improve model prediction and further support the study design and conduct of a first-in-human study., (© 2023 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Obesity is driven by an imbalance between caloric intake and energy expenditure, causing excessive storage of triglycerides in adipose tissue at different sites around the body. Increased visceral adipose tissue (VAT) is associated with diabetes, while pericardial adipose tissue (PAT) is associated with cardiac pathology. Adipose tissue can expand either through cellular hypertrophy or hyperplasia, with the former correlating with decreased metabolic health in obesity. The aim of this study was to determine how VAT and PAT remodel in response to obesity, stress, and exercise. Here we have used the male obese Zucker rats, which carries two recessive fa alleles that result in the development of hyperphagia with reduced energy expenditure, resulting in morbid obesity and leptin resistance. At 9 weeks of age, a group of lean (Fa/Fa or Fa/fa) Zucker rats (LZR) and obese (fa/fa) Zucker rats (OZR) were treated with unpredictable chronic mild stress or exercise for 8 weeks. To determine the phenotype for PAT and VAT, tissue cellularity and gene expression were analyzed. Finally, leptin signaling was investigated further using cultured 3T3-derived adipocytes. Tissue cellularity was determined following hematoxylin and eosin (H&E) staining, while qPCR was used to examine gene expression. PAT adipocytes were significantly smaller than those from VAT and had a more beige-like appearance in both LZR and OZR. In the OZR group, VAT adipocyte cell size increased significantly compared with LZR, while PAT showed no difference. Exercise and stress resulted in a significant reduction in VAT cellularity in OZR, while PAT showed no change. This suggests that PAT cellularity does not remodel significantly compared with VAT. These data indicate that the extracellular matrix of PAT is able to remodel more readily than in VAT. In the LZR group, exercise increased insulin receptor substrate 1 (IRS1) in PAT but was decreased in the OZR group. In VAT, exercise decreased IRS1 in LZR, while increasing it in OZR. This suggests that in obesity, VAT is more responsive to exercise and subsequently becomes less insulin resistant compared with PAT. Stress increased PPAR-γ expression in the VAT but decreased it in the PAT in the OZR group. This suggests that in obesity, stress increases adipogenesis more significantly in the VAT compared with PAT. To understand the role of leptin signaling in adipose tissue remodeling mechanistically, JAK2 autophosphorylation was inhibited using 5 μM 1,2,3,4,5,6-hexabromocyclohexane (Hex) in cultured 3T3-derived adipocytes. Palmitate treatment was used to induce cellular hypertrophy. Hex blocked adipocyte hypertrophy in response to palmitate treatment but not the increase in lipid droplet size. These data suggest that leptin signaling is necessary for adipocyte cell remodeling, and its absence induces whitening. Taken together, our data suggest that leptin signaling is necessary for adipocyte remodeling in response to obesity, exercise, and psychosocial stress., (© 2023 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Previous studies have suggested that the loss of microvessel density in the peripheral circulation with evolving metabolic disease severity represents a significant contributor to impaired skeletal muscle oxygenation and fatigue-resistance. Based on this and our recent work, we hypothesized that cerebral microvascular rarefaction was initiated from the increased prooxidant and proinflammatory environment with metabolic disease and is predictive of the severity of the emergence of depressive symptoms in obese Zucker rats (OZRs). In male OZR, cerebrovascular rarefaction followed the emergence of elevated oxidant and inflammatory environments characterized by increased vascular production of thromboxane A 2 (TxA 2 ). The subsequent emergence of depressive symptoms in OZR was associated with the timing and severity of the rarefaction. Chronic intervention with antioxidant (TEMPOL) or anti-inflammation (pentoxifylline) therapy blunted the severity of rarefaction and depressive symptoms, although the effectiveness was limited. Blockade of TxA 2 production (dazmegrel) or action (SQ-29548) resulted in a stronger therapeutic effect, suggesting that vascular production and action represent a significant contributor to rarefaction and the emergence of depressive symptoms with chronic metabolic disease (although other pathways clearly contribute as well). A de novo biosimulation of cerebrovascular oxygenation in the face of progressive rarefaction demonstrates the increased probability of generating hypoxic regions within the microvascular networks, which could contribute to impaired neuronal metabolism and the emergence of depressive symptoms. The results of the present study also implicate the potential importance of aggressive prodromic intervention in reducing the severity of chronic complications arising from metabolic disease. NEW & NOTEWORTHY With clinical studies linking vascular disease risk to depressive symptom emergence, we used obese Zucker rats, a model of chronic metabolic disease, to identify potential mechanistic links between these two negative outcomes. Depressive symptom severity correlated with the extent of cerebrovascular rarefaction, after increased vascular oxidant stress/inflammation and TxA 2 production. Anti-TxA 2 interventions prevasculopathy blunted rarefaction and depressive symptoms, while biosimulation indicated that cerebrovascular rarefaction increased hypoxia within capillary networks as a potential contributing mechanism.