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Abstract Background Nonalcoholic fatty liver disease (NAFLD) is the main reason for cirrhosis and hepatocellular carcinoma. As a starting point for NAFLD, the treatment of nonalcoholic fatty liver (NAFL) is receiving increasing attention. Mice fed a high‐fat diet (HFD) and hereditary leptin deficiency (ob/ob) mice are important NAFL animal models. However, the comparison of these mouse models with human NAFL is still unclear. Methods In this study, HFD‐fed mice and ob/ob mice were used as NAFL animal models. Liver histopathological characteristics were compared, and liver transcriptome from both mouse models was performed using RNA sequencing (RNA‐seq). RNA‐seq data obtained from the livers of NAFL patients was downloaded from the GEO database. Global gene expression profiles in the livers were further analyzed using functional enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Results Our results showed that the biochemical parameters of both mouse models and human NAFL were similar. Compared with HFD‐fed mice, ob/ob mice were more similar in histologic appearance to NAFL patients. The liver transcriptome characteristics partly overlapped in mice and humans. Furthermore, in the NAFL pathway, most genes showed similar trends in mice and humans, thus demonstrating that both types of mice can be used as models for basic research on NAFL, considering the differences. Conclusion Our findings show that HFD‐fed mice and ob/ob mice can mimic human NAFL partly in pathophysiological process. The comparative analysis of liver transcriptome profile in mouse models and human NAFL presented here provides insights into the molecular characteristics across these NAFL models.

Type 2 diabetes is a disease characterized by hyperglycemia and is a growing health problem worldwide. Since many known diabetes drugs are side effects, it is necessary to develop natural substances with guaranteed safety. HM-chromanone isolated from Portulaca oleracea L. is a homoisoflavonoid compound. We investigated the effects of HM-chromanone on hyperglycemia and its mechanism in C57BL/6J ob/ob mice. C57BL/6J-Jms Slc mice were used as the control group, and C57BL/6J-ob/ob mice were divided into three groups: ob/ob (control), metformin (Met; positive control), and HM-chromanone (HMC). Fasting blood glucose was lower in the HMC group than those in the ob/ob group. Insulin resistance was improved by reducing HbA1c, plasma insulin, and HOMA-IR levels in the HMC group. HMC administration decreased the phosphorylation of IRS-1ser307 and increased the phosphorylation of IRS-1tyr612, PI3K, phosphorylation of AKTser473, and PM-GLUT4 in the skeletal muscles of ob/ob mice, indicating improved insulin signaling. HMC administration also increased the phosphorylation of FOXO1 in the liver of ob/ob mice. This inhibited PEPCK and G6pase involved in gluconeogenesis and regulated phosphorylation of glycogen synthase kinase 3β and glycogen synthase involved in glycogen synthesis. In conclusion, HM-chromanone ameliorates hyperglycemia by PI3K/AKT and improves the FOXO1 in ob/ob mice. [ABSTRACT FROM AUTHOR]

The blockade of metabotropic glutamate receptor type 5 (mGluR5) was previously found to reduce fat accumulation in HEPG2 cells. Here, we evaluated the effects of mGluR5 blockade in a mouse model of steatosis. Male ob/ob mice fed a high-fat diet were treated with MPEP or vehicle. After 7 weeks, liver biopsies were collected, and nuclei were isolated from fresh tissue. Lipid droplet area and collagen deposition were evaluated on tissue slices; total lipids, lipid peroxidation, and ROS were evaluated on tissue homogenates; PPARα, SREBP-1, mTOR, and NF-κB were assayed on isolated nuclei by Western Blot. Target genes of the above-mentioned factors were assayed by RT-PCR. Reduced steatosis and hepatocyte ballooning were observed in the MPEP group with respect to the vehicle group. Concomitantly, increased nuclear PPARα and reduced nuclear SREBP-1 levels were observed in the MPEP group. Similar trends were obtained in target genes of PPARα and SREBP-1, Acox1 and Acc1, respectively. MPEP administration also reduced oxidative stress and NF-κB activation, probably via NF-κB inhibition. Levels of common markers of inflammation (Il-6, Il1β and Tnf-α) and oxidative stress (Nrf2) were significantly reduced. mTOR, as well as collagen deposition, were unchanged. Concluding, MPEP, a selective mGluR5 negative allosteric modulator, reduces both fat accumulation and oxidative stress in a 7-week murine model of steatosis. Although underlying mechanisms need to be further investigated, this is the first in vivo study showing the beneficial effects of MPEP in a murine model of steatosis. [ABSTRACT FROM AUTHOR]

Background and Objective: Leptin-deficient obesity is associated with various systemic diseases including diabetes and low bone mass phenotype. However, the periodontal status of leptin-deficient obese individuals is still unclear. In this study, we aimed to analyze the periodontal status, alveolar bone phenotype, and oral microbiome status in leptin-deficient obese mice (ob/ob mice). Methods: This study used 12-week- old wild-type and ob/ob male mice. The alveolar bone phenotype and periodontal status in the maxilla were analyzed by micro-CT and histological analysis. Osteoclasts in alveolar bone were visualized by TRAP staining. Expressions of inflammatory markers (MMP-9, IL-1β, and TGF-β1) and osteoclastogenic markers (RANKL and OPG) in periodontium were analyzed by immunohistochemistry and RT-qPCR. The oral microbiome was analyzed by 16 S rDNA sequencing. Results: CEJ-ABC distance in maxillary molars (M1-M3) of ob/ob mice was significantly higher compared with that of wild-type. The alveolar bone BV/TV ratio was reduced in ob/ob mice compared with wild-type. Higher numbers of osteoclasts were observed in ob/ob mice alveolar bone adjacent to the molar root. Epithelial hyperplasia in gingiva and disordered periodontal ligaments was observed in ob/ob mice. RANKL/OPG expression ratio was increased in ob/ob mice compared with wild-type. Expressions of inflammatory markers MMP-9, IL-1β, and TGF-β1 were increased in ob/ob mice compared with wild-type. Oral microbiome analysis showed that beneficial bacteria Akkermansia and Ruminococcaceae_UCG_014 were more abundant in the wild-type mice while the inflammation-related Flavobacterium was more abundant in ob/ob mice. Conclusion: In conclusion, ob/ob mice showed higher expressions of inflammatory factors, increased alveolar bone loss, lower abundance of the beneficial bacteria, and higher abundance of inflammatory bacteria in the oral cavity, suggesting leptin-deficient obesity as a risk factor for periodontitis development in ob/ob mice. [ABSTRACT FROM AUTHOR]

Cytidine and uridine are endogenous metabolites in the pyrimidine metabolism pathway, and cytidine is a substrate that can be metabolized into uridine via cytidine deaminase. Uridine has been widely reported to be effective in regulating lipid metabolism. However, whether cytidine could ameliorate lipid metabolism disorder has not yet been investigated. In this research, ob/ob mice were used, and the effect of cytidine (0.4 mg/mL in drinking water for five weeks) on lipid metabolism disorder was evaluated in terms of an oral glucose tolerance test, serum lipid levels, liver histopathological analysis and gut microbiome analysis. Uridine was used as a positive control. Our findings reveal that cytidine could alleviate certain aspects of dyslipidemia and improve hepatic steatosis via modulating the gut microbiota composition in ob/ob mice, especially increasing the abundance of short-chain fatty acids-producing microbiota. These results suggest that cytidine supplementation could be a potential therapeutic approach for dyslipidemia. [ABSTRACT FROM AUTHOR]

This study investigated whether HM-chromanone, a bioactive compound isolated from Portulaca oleracea L., inhibits lipid accumulation in adipose tissue and liver of C57BL/6J ob/ob mice. C57BL/6J mice were used for the normal group and C57BL/6J ob/ob mice were randomly divided into three groups: ob/ob, metformin and HM-chromanone. In the HM-chromanone group, body and liver weight, fat mass and fat size were significantly lower than that in the ob/ob group. The HM-chromanone group also showed lower serum lipid levels and hepatic lipid accumulation compared with the ob/ob group. HM-chromanone administration significantly activated adenosine monophosphate-activated protein kinase (AMPK) and inhibited sterol regulatory element binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) in adipose tissue and liver. These results suggest that HM-chromanone potentially suppresses lipid accumulation by modulating AMPK/SREBP-1c pathway in adipose tissue and liver of ob/ob mice.

Leptin is recognized as an anorexigenic hormone. In its absence (e.g., in ob/ob mutant mice), mice become obese, primarily as a result of hyperphagia. A recurrent question is whether, additionally, leptin is thermogenic and thus also an antiobesity hormone in this way. We have earlier reviewed available data and have concluded that most articles implying a thermogenic effect of leptin have based this on a misconstrued division by body weight. Here, we have collected evidence that the remaining observations that imply that leptin is a thermogenic hormone are better understood as implying that leptin is an antitorpor hormone. Leptin levels increase in proportion to the body's energy reserves (i.e., stored lipids in the adipose tissue), and leptin thus serves as an indicator of energy availability. In the absence of leptin, ob/ob mice are exceedingly prone to enter daily torpor, since the absence of leptin causes them to perceive a lack of body energy reserves that, in combination with restricted or no food, induces them to enter the torpid state to save energy. This antitorpor effect of leptin probably explains the following earlier observations. First, ob/ob mice have the ability to gain weight even when pair fed with leptin-treated ob/ob mice. This is understood as follows: In the leptin-treated ob/ob mice, food intake is reduced. Untreated pair-fed mice enter daily torpor, and this markedly lowers total daily energy expenditure; the resulting surplus food energy is then accumulated as fat in these mice. However, ob/ob mice fed ad lib. do not enter torpor, so under normal conditions this mechanism does not contribute to the obesity found in the ob/ob mice. Second, neonatal ob/ob mice have the ability to become obese despite eating the same amount as wild-type mice: this is understood as these mice similarly entering daily torpor. Third, ob/ob mice on the C57BL/6J background have a lower metabolic rate: these mice were examined in the absence of food, and torpor was thus probably induced. Fourth, ob/ob mice have apparent high cold sensitivity: these mice experienced cold in the absence of food and would immediately enter deep torpor. It is suggested that this novel explanation of how the antitorpor effects of leptin affect mouse energy metabolism can open new avenues for leptin research. [ABSTRACT FROM AUTHOR]

Loureirin B (LB), an active component of Resina Draconis, exhibits hypoglycemic and hypolipidemic effects; however, its mode of action remains unclear. Here, ob/ob mice were utilized to investigate the effects of LB on the regulation of glucolipid metabolism disorders. Non-targeted metabolomics and 16S rDNA sequencing were performed to elucidate the potential mechanisms involved. Results indicated that LB treatment (45 mg/kg) significantly improved glucose intolerance and insulin resistance, reduced lipid levels, and alleviated hepatic steatosis. Non-targeted metabolomics analysis revealed that LB treatment regulated bile acid levels. Quantification of liver bile acids demonstrated that LB treatment significantly decreased the ratio of 12α-OH to non-12α-OH bile acids in the liver. 16S rDNA sequencing results showed that LB treatment increased the abundance of short-chain fatty acid-producing microbiota while decreasing the abundance of bile salt hydrolase (BSH) enzyme-producing microbiota. In conclusion, LB ameliorates glucolipid metabolism disorders by regulating liver bile acid levels and modulating the composition of the gut microbiota., (© 2024 Wiley‐VCH GmbH.)

Diabetic nephropathy (DN) is a major cause of global kidney failure. While histological kidney biopsy is the gold standard for diagnosis, it primarily reveals tissue morphology. In contrast, near-infrared (NIR) microscopy offers a label-free method for detailed molecular characterization of kidney tissue. Hematoxylin and eosin-stained kidney tissue samples from 17 ob/ob mice with DN and 14 healthy mice were examined using Fourier transform-NIR microscopy. Four different spectra were obtained from both the mesangium and tubulus. NIR spectral analysis unveiled distinct differences in wavenumbers between DN-affected and healthy kidneys, notably in the carbohydrate and protein-associated region (5500-4200 cm -1 ). In the mesangium, DN tissue samples exhibited higher median values at 4235 cm -1 , 4659 cm -1 , 4844 cm -1 , 4906 cm -1 , and 5222 cm -1 compared to controls (P < 0.05, P < 0.01, P < 0.05, P < 0.05 and P < 0.001, respectively). In tubular spectra, higher median values were found at 4258 cm -1 , 4659 cm -1 , 5222 cm -1 , and 5346 cm -1 in the DN group (P < 0.01, P < 0.05, P < 0.05 and P < 0.01, respectively). These spectral differences strongly correlated with metabolic, histologic, and urinary parameters, providing valuable DN progression insights. The classification model achieved a visible clustering between the control and DN group for both the mesangial and tubular measurements. NIR microscopy demonstrated significant spectral differences between DN and healthy kidney tissues in mice, hinting at its potential for providing chemical insights, aiding in more accurate diagnoses, and offering a foundation for further clinical exploration and potential therapeutic advancements in DN., Competing Interests: Declaration of competing interest Declarations of interest: none., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Obesity and atherosclerosis are the most prevalent metabolic diseases. ApoE−/− and ob/ob mice are widely used as models to study the pathogenesis of these diseases. However, how gut microbes, gut bacteriophages, and metabolites change in these two disease models is unclear. Here, we used wild-type C57BL/6J (Wt) mice as normal controls to analyze the intestinal archaea, bacteria, bacteriophages, and microbial metabolites of ob/ob and ApoE−/− mice through metagenomics and metabolomics. Analysis of the intestinal archaea showed that the abundances of Methanobrevibacter and Halolamina were significantly increased and decreased, respectively, in the ob/ob group compared with those in the Wt and ApoE−/− groups (p < 0.05). Compared with those of the Wt group, the relative abundances of the bacterial genera Enterorhabdus, Alistipes, Bacteroides, Prevotella, Rikenella, Barnesiella, Porphyromonas, Riemerella, and Bifidobacterium were significantly decreased (p < 0.05) in the ob/ob mice, and the relative abundance of Akkermansia was significantly decreased in the ApoE−/− group. The relative abundances of A. muciniphila and L. murinus were significantly decreased and increased, respectively, in the ob/ob and ApoE−/− groups compared with those of the Wt group (p < 0.05). Lactobacillus_ prophage_ Lj965 and Lactobacillus _ prophage _ Lj771 were significantly more abundant in the ob/ob mice than in the Wt mice. Analysis of the aminoacyl-tRNA biosynthesis metabolic pathway revealed that the enriched compounds of phenylalanine, glutamine, glycine, serine, methionine, valine, alanine, lysine, isoleucine, leucine, threonine, tryptophan, and tyrosine were downregulated in the ApoE−/− mice compared with those of the ob/ob mice. Aminoacyl-tRNA synthetases are considered manifestations of metabolic diseases and are closely associated with obesity, atherosclerosis, and type 2 diabetes. These data offer new insight regarding possible causes of these diseases and provide a foundation for studying the regulation of various food nutrients in metabolic disease models.

Introduction: The leptin signaling pathway plays an important role as a key regulator of glucose homeostasis, metabolism control and systemic inflammatory responses. However, the metabolic effects of leptin on infectious diseases, for example tuberculosis (TB), are still little known. Objectives: In this study, we aim to investigate the role of leptin on metabolism in the absence and presence of mycobacterial infection in zebrafish larvae and mice. Methods: Metabolites in entire zebrafish larvae and the blood of mice were studied using high-resolution magic-angle-spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy and mass spectrometry, respectively. For transcriptome studies of zebrafish larvae, deep RNA sequencing was used. Results: The results show that leptin mutation leads to a similar metabolic syndrome as caused by mycobacterial infection in the two species, characterized by the decrease of 11 amine metabolites. In both species, this metabolic syndrome was not aggravated further when the leptin mutant was infected by mycobacteria. Therefore, we conclude that leptin and mycobacterial infection are both impacting metabolism non-synergistically. In addition, we studied the transcriptomes of lepbibl54 mutant zebrafish larvae and wild type (WT) siblings after mycobacterial infection. These studies showed that mycobacteria induced a very distinct transcriptome signature in the lepbibl54 mutant zebrafish compared to WT sibling control larvae. Furthermore, lepbibl55 Tg (pck1:luc1) zebrafish line was constructed and confirmed this difference in transcriptional responses. Conclusions: Leptin mutation and TB lead non-synergistically to a similar metabolic syndrome. Moreover, different transcriptomic responses in the lepbibl54 mutant and TB can lead to the similar metabolic end states. [ABSTRACT FROM AUTHOR]

BACKGROUND: Obesity and leptin deficiency are associated with compromised bone regeneration. OBJECTIVE: This study aims to investigate the role of locally administrated low-dose BMP2+leptin on bone regeneration in leptin-deficient obese (ob/ob) mice. METHODS: Wildtype (WT) and ob/ob mice were divided into 3 groups (4 mice/group): BMP2 (5 μg) group, BMP2+low-dose leptin (1 μg) group, and BMP2+high-dose leptin (2.5 μg) group. WT mice were used as control mice. An equal size absorbable collagen sponge was prepared by loading the BMP2 or/and leptin and implanted subcutaneously. After 19 days, samples were collected and analyzed by micro-CT and H&E staining. RESULTS: No significant difference in bone regeneration among the three groups in WT mice. Quantification of newly formed bone parameters from micro-CT and H&E staining showed that low-dose BMP2 treatment formed less new bone in ob/ob mice compared to WT. BMP2+low-dose leptin treatment substantially rescued the compromised bone regeneration in ob/ob mice up to the level in WT mice. However, the BMP2 and high dose of leptin failed to rescue the compromised bone regeneration in ob/ob mice. CONCLUSION: Our findings suggest that a combination of the low-dose BMP2 and leptin could be a strategy to promote osteogenesis in obese populations with leptin deficiency. [ABSTRACT FROM AUTHOR]

Abstract Background Leptin plays a critical role in the regulation of metabolic homeostasis. However, the molecular mechanism and cross talks between leptin and metabolic pathways leading to metabolic homeostasis across different species are not clear. This study aims to explore the effects of leptin in mice and zebrafish larvae by integration of metabolomics and transcriptomics. Different metabolomic approaches including mass spectrometry, nuclear magnetic resonance (NMR) and high-resolution magic-angle-spinning NMR spectrometry were used to investigate the metabolic changes caused by leptin deficiency in mutant ob/ob adult mice and lepb −/− zebrafish larvae. For transcriptome studies, deep RNA sequencing was used. Results Thirteen metabolites were identified as common biomarkers discriminating ob/ob mice and lepb −/− zebrafish larvae from their respective wild type controls: alanine, citrulline, ethanolamine, glutamine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, putrescine, serine and threonine. Moreover, we also observed that glucose and lipid levels were increased in lepb −/− zebrafish larvae compared to the lepb +/+ group. Deep sequencing showed that many genes involved in proteolysis and arachidonic acid metabolism were dysregulated in ob/ob mice heads and lepb mutant zebrafish larvae compared to their wild type controls, respectively. Conclusions Leptin deficiency leads to highly similar metabolic alterations in metabolites in both mice and zebrafish larvae. These metabolic changes show similar features as observed during progression of tuberculosis in human patients, mice and zebrafish larvae. In addition, by studying the transcriptome, we found similar changes in gene regulation related to proteolysis and arachidonic acid metabolism in these two different in vivo models.

Type 2 diabetes is a disease characterized by hyperglycemia and is a growing health problem worldwide. Since many known diabetes drugs are side effects, it is necessary to develop natural substances with guaranteed safety. HM-chromanone isolated from Portulaca oleracea L. is a homoisoflavonoid compound. We investigated the effects of HM-chromanone on hyperglycemia and its mechanism in C57BL/6J ob/ob mice. C57BL/6J-Jms Slc mice were used as the control group, and C57BL/6J-ob/ob mice were divided into three groups: ob/ob (control), metformin (Met; positive control), and HM-chromanone (HMC). Fasting blood glucose was lower in the HMC group than those in the ob/ob group. Insulin resistance was improved by reducing HbA1c, plasma insulin, and HOMA-IR levels in the HMC group. HMC administration decreased the phosphorylation of IRS-1ser307 and increased the phosphorylation of IRS-1tyr612, PI3K, phosphorylation of AKTser473, and PM-GLUT4 in the skeletal muscles of ob/ob mice, indicating improved insulin signaling. HMC administration also increased the phosphorylation of FOXO1 in the liver of ob/ob mice. This inhibited PEPCK and G6pase involved in gluconeogenesis and regulated phosphorylation of glycogen synthase kinase 3β and glycogen synthase involved in glycogen synthesis. In conclusion, HM-chromanone ameliorates hyperglycemia by PI3K/AKT and improves the FOXO1 in ob/ob mice.

The blockade of metabotropic glutamate receptor type 5 (mGluR5) was previously found to reduce fat accumulation in HEPG2 cells. Here, we evaluated the effects of mGluR5 blockade in a mouse model of steatosis. Male ob/ob mice fed a high-fat diet were treated with MPEP or vehicle. After 7 weeks, liver biopsies were collected, and nuclei were isolated from fresh tissue. Lipid droplet area and collagen deposition were evaluated on tissue slices; total lipids, lipid peroxidation, and ROS were evaluated on tissue homogenates; PPARα, SREBP-1, mTOR, and NF-κB were assayed on isolated nuclei by Western Blot. Target genes of the above-mentioned factors were assayed by RT-PCR. Reduced steatosis and hepatocyte ballooning were observed in the MPEP group with respect to the vehicle group. Concomitantly, increased nuclear PPARα and reduced nuclear SREBP-1 levels were observed in the MPEP group. Similar trends were obtained in target genes of PPARα and SREBP-1, Acox1 and Acc1, respectively. MPEP administration also reduced oxidative stress and NF-κB activation, probably via NF-κB inhibition. Levels of common markers of inflammation (Il-6, Il1β and Tnf-α) and oxidative stress (Nrf2) were significantly reduced. mTOR, as well as collagen deposition, were unchanged. Concluding, MPEP, a selective mGluR5 negative allosteric modulator, reduces both fat accumulation and oxidative stress in a 7-week murine model of steatosis. Although underlying mechanisms need to be further investigated, this is the first in vivo study showing the beneficial effects of MPEP in a murine model of steatosis.

Cytidine and uridine are endogenous metabolites in the pyrimidine metabolism pathway, and cytidine is a substrate that can be metabolized into uridine via cytidine deaminase. Uridine has been widely reported to be effective in regulating lipid metabolism. However, whether cytidine could ameliorate lipid metabolism disorder has not yet been investigated. In this research, ob/ob mice were used, and the effect of cytidine (0.4 mg/mL in drinking water for five weeks) on lipid metabolism disorder was evaluated in terms of an oral glucose tolerance test, serum lipid levels, liver histopathological analysis and gut microbiome analysis. Uridine was used as a positive control. Our findings reveal that cytidine could alleviate certain aspects of dyslipidemia and improve hepatic steatosis via modulating the gut microbiota composition in ob/ob mice, especially increasing the abundance of short-chain fatty acids-producing microbiota. These results suggest that cytidine supplementation could be a potential therapeutic approach for dyslipidemia.

Introduction/aims: Obesity is a factor contributing to suboptimal improvement of motor function in peripheral nerve disorders. In this study we aimed to evaluate the skeletal muscles during denervation and reinnervation after nerve crush injury in leptin-deficient (ob/ob) mice.Methods: Experiments were performed on the skeletal muscles of the hindlimbs in 20 male ob/ob mice and controls. Characteristics of the gastrocnemius muscles were evaluated by histological analysis, immunohistological analysis, and Sircol-collagen assay after measurement of body weight and wet weight of the skeletal muscles, and by walking track analysis. The sciatic nerve was denervated by crushing with smooth forceps and reinnervation was evaluated.Results: Gastrocnemius wet weight was significantly lower in the ob/ob mice than in the control mice. A smaller cross-sectional area of type II fibers and increase of type I fiber grouping of the skeletal muscles was demonstrated in the ob/ob mice. After nerve injury, motor function recovery was equal between the groups but the cross-sectional area of type II fibers was significantly smaller in the ob/ob mice than in control mice at 4 weeks. The denervated muscles showed an increase in collagen deposition in the interstitial space; predominant in the ob/ob mice after nerve injury.Discussion: The results of this study suggest that fibrosis in the skeletal muscle of obese patients after nerve injury is prominent, which may impair improvement of muscle function after treatment of peripheral nerve disorders. [ABSTRACT FROM AUTHOR]

Background: Obesity is one of the main health problems in the world today, and dysbiosis seems to be one of the factors involved. The aim of this study was to examine the impact of synbiotic supplementation on obesity and the microbiota in ob/ob mice. Twenty animals were divided into four groups: obese treated (OT), obese control (OC), lean treated (LT) and lean control (LC). All animals received a standard diet for 8 weeks. The treated groups received a synbiotic (Simbioflora-Invictus Farmanutrição Ltd., Sao Paulo, Brazil) in water, while the nontreated groups received only water. After 8 weeks, all animals were sacrificed, and gut tissue and stool samples were collected for mRNA isolation and microbiota analysis, respectively. β-Catenin, occludin, cadherin and zonulin in the gut tissue were analyzed via RT-qPCR. Microbiome DNA was extracted from stool samples and sequenced using an Ion PGM Torrent platform. Results: Synbiotic supplementation reduced body weight gain in the OT group compared with the OC group (p = 0.0398) and was associated with an increase in Enterobacteriaceae (p = 0.005) and a decrease in Cyanobacteria (p = 0.047), Clostridiaceae (p = 0.026), Turicibacterales (p = 0.005) and Coprococcus (p = 0.047). On the other hand, a significant reduction in Sutterella (p = 0.009) and Turicibacter (p = 0.005) bacteria was observed in the LT group compared to the LC group. Alpha and beta diversities were different among all treated groups. β-Catenin gene expression was significantly decreased in the gut tissue of the OT group (p ≤ 0.0001) compared to the other groups. No changes were observed in occludin, cadherin or zonulin gene expression in the gut tissue. Conclusions: Synbiotic supplementation prevents excessive weight gain, modulates the gut microbiota, and reduces β-catenin expression in ob/ob mice.

Background: Leptin plays a critical role in the regulation of metabolic homeostasis. However, the molecular mechanism and cross talks between leptin and metabolic pathways leading to metabolic homeostasis across different species are not clear. This study aims to explore the effects of leptin in mice and zebrafish larvae by integration of metabolomics and transcriptomics. Different metabolomic approaches including mass spectrometry, nuclear magnetic resonance (NMR) and high-resolution magic-angle-spinning NMR spectrometry were used to investigate the metabolic changes caused by leptin deficiency in mutant ob/ob adult mice and lepb−/− zebrafish larvae. For transcriptome studies, deep RNA sequencing was used. Results: Thirteen metabolites were identified as common biomarkers discriminating ob/ob mice and lepb−/− zebrafish larvae from their respective wild type controls: alanine, citrulline, ethanolamine, glutamine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, putrescine, serine and threonine. Moreover, we also observed that glucose and lipid levels were increased in lepb−/− zebrafish larvae compared to the lepb+/+ group. Deep sequencing showed that many genes involved in proteolysis and arachidonic acid metabolism were dysregulated in ob/ob mice heads and lepb mutant zebrafish larvae compared to their wild type controls, respectively. Conclusions: Leptin deficiency leads to highly similar metabolic alterations in metabolites in both mice and zebrafish larvae. These metabolic changes show similar features as observed during progression of tuberculosis in human patients, mice and zebrafish larvae. In addition, by studying the transcriptome, we found similar changes in gene regulation related to proteolysis and arachidonic acid metabolism in these two different in vivo models. [ABSTRACT FROM AUTHOR]

Fatty acid synthase (FASN) participates in many fundamental biological processes, including energy storage and signal transduction, and is overexpressed in many cancer cells. We previously showed in a context of lipogenesis that FASN is protected from degradation by its interaction with O-GlcNAc transferase (OGT) in a nutrient-dependent manner. We and others also reported that OGT and O-GlcNAcylation up-regulate the PI3K/AKT/mTOR pathway that senses mitogenic signals and nutrient availability to drive cell cycle. Using biochemical and microscopy approaches, we show here that FASN co-localizes with OGT in the cytoplasm and, to a lesser extent, in the membrane fraction. This interaction occurs in a cell cycle-dependent manner, following the pattern of FASN expression. Moreover, we show that FASN expression depends on OGT upon serum stimulation. The level of FASN also correlates with the activation of the PI3K/AKT/mTOR pathway in hepatic cell lines, and in livers of obese mice and in a chronically activated insulin and mTOR signaling mouse model (PTEN-null mice). These results indicate that FASN is under a dual control of O-GlcNAcylation and mTOR pathways. In turn, blocking FASN with the small-molecule inhibitor C75 reduces both OGT and O-GlcNAcylation levels, and mTOR activation, highlighting a novel reciprocal regulation between these actors. In addition to the role of O-GlcNAcylation in tumorigenesis, our findings shed new light on how aberrant activity of FASN and mTOR signaling may promote the emergence of hepatic tumors. [ABSTRACT FROM AUTHOR]

Background: The gut microbiota plays a role in the occurrence of nonalcoholic fatty liver disease (NAFLD), notably through the production of bioactive metabolites. Indole, a bacterial metabolite of tryptophan, has been proposed as a pivotal metabolite modulating inflammation, metabolism, and behavior.Objectives: The aim of our study was to mimic an upregulation of intestinal bacterial indole production and to evaluate its potential effect in vivo in 2 models of NAFLD.Methods: Eight-week-old leptin-deficient male ob/ob compared with control ob/+ mice (experiment 1), and 4-5-wk-old C57BL/6JRj male mice fed a low-fat (LF, 10 kJ%) compared with a high-fat (HF, 60 kJ%) diet (experiment 2), were given plain water or water supplemented with a physiological dose of indole (0.5 mM, n ≥6/group) for 3 wk and 3 d, respectively. The effect of the treatments on the liver, intestine, adipose tissue, brain, and behavior was assessed.Results: Indole reduced hepatic expression of genes involved in inflammation [C-C motif chemokine ligand 2 (Ccl2), C-X-C motif chemokine ligand 2 (Cxcl2); 3.3- compared with 5.0-fold, and 2.4- compared with 3.3-fold of control ob/+ mice, respectively, P < 0.05], and in macrophage activation [Cd68, integrin subunit α X (Itgax); 2.1- compared with 2.5-fold, and 5.0- compared with 6.4-fold of control ob/+ mice, respectively, P < 0.01] as well as markers of hepatic damage (alaninine aminotransferase; -32%, P < 0.001) regardless of genotype in experiment 1. Indole had no effect on hepatic inflammation in mice fed the LF or HF diet in experiment 2. Indole did not change hepatic lipid content, anxiety-like behavior, or inflammation in the ileum, adipose tissue, and brain in experiment 1.Conclusions: Our results support the efficacy of indole to reduce hepatic damage and associated inflammatory response and macrophage activation in ob/ob mice. These modifications appear to be attributable to direct effects of indole on the liver, rather than through effects on the adipose tissue or intestinal barrier. [ABSTRACT FROM AUTHOR]

Abstract Background Growing evidence supports the role of gut microbiota in obesity and its related disorders including type 2 diabetes. Ob/ob mice, which are hyperphagic due to leptin deficiency, are commonly used models of obesity and were instrumental in suggesting links between gut microbiota and obesity. Specific changes in their gut microbiota such as decreased microbial diversity and increased Firmicutes to Bacteroidetes ratio have been suggested to contribute to obesity via increased microbiota capacity to harvest energy. However, the differential development of ob/ob mouse gut microbiota compared to wild type microbiota and the role of hyperphagia in their metabolic impairment have not been investigated thoroughly. Results We performed a 10-week long study in ob/ob (n = 12) and wild type control (n = 12) mice fed ad libitum. To differentiate effects of leptin deficiency from hyperphagia, we pair-fed an additional group of ob/ob mice (n = 11) based on the food consumption of control mice. Compared to control mice, ob/ob mice fed ad libitum exhibited compromised glucose metabolism and increased body fat percentage. Pair-fed ob/ob mice exhibited even more compromised glucose metabolism and maintained strikingly similar high body fat percentage at the cost of lean body mass. Acclimatization of the microbiota to our facility took up to 5 weeks. Leptin deficiency impacted gut microbial composition, explaining 18.3% of the variance. Pair-feeding also altered several taxa, although the overall community composition at the end of the study was not significantly different. We found 24 microbial taxa associations with leptin deficiency, notably enrichment of members of Lactobacillus and depletion of Akkermansia muciniphila. Microbial metabolic functions related to energy harvest, including glycan degradation, phosphotransferase systems and ABC transporters, were enriched in the ob/ob mice. Taxa previously reported as relevant for obesity were associated with body weight, including Oscillibacter and Alistipes (both negatively correlated) and Prevotella (positively correlated). Conclusions Leptin deficiency caused major changes in the mouse gut microbiota composition. Several microbial taxa were associated with body composition. Pair-fed mice maintained a pre-set high proportion of body fat despite reduced calorie intake, and exhibited more compromised glucose metabolism, with major implications for treatment options for genetically obese individuals.

Abstract Background Leptin is an adipokine that regulates energy homeostasis and is also needed for normal bone growth and maintenance. Mutation in the lep gene, which characterizes the ob/ob mouse model, results in the development of obesity and type 2 diabetes mellitus, as well as reduced limb bone length and increased fracture risk. However, the relationship between limb bone length and growth plate cartilage structure in obese diabetic adolescents is incompletely understood. Here, we tested the hypothesis that leptin deficiency affects the microstructure of growth plate cartilage in juvenile ob/ob mice. Methods Tibial growth plate cartilage structure was compared between lean and obese, leptin-deficient (ob/ob) female mice aged 10 weeks. We used confocal laser scanning microscopy to assess 3D histological differences in Z stacks of growth plate cartilage at 0.2 µm intervals, 80–100 µm in depth. Histomorphometric comparisons were made between juvenile lean and ob/ob mice. Results We found obese mice have significantly reduced tibial length and growth plate height in comparison with lean mice (P

Meretrix lusoria (M. lusoria) is an economically important shellfish which is widely distributed in South Eastern Asia that contains bioactive peptides, proteins, and enzymes. In the present study, the extracted meat content of M. lusoria was enzymatic hydrolyzed using four different commercial proteases (neutrase, protamex, alcalase, and flavourzyme). Among the enzymatic hydrolysates, M. lusoria protamex hydrolysate (MLPH) fraction with MW ≤ 1 kDa exhibited the highest free radical scavenging ability. The MLPH fraction was further purified and an amino acid sequence (KDLEL, 617.35 Da) was identified by LC-MS/MS analysis. The purpose of this study was to investigate the anti-obesity and anti-hyperglycemic effects of MLPH containing antioxidant peptides using ob/ob mice. Treatment with MLPH for 6 weeks reduced body and organ weight and ameliorated the effects of hepatic steatosis and epididymal fat, including a constructive effect on hepatic and serum marker parameters. Moreover, hepatic antioxidant enzyme activities were upregulated and impaired glucose tolerance was improved in obese control mice. In addition, MLPH treatment markedly suppressed mRNA expression related to lipogenesis and hyperglycemia through activation of AMPK phosphorylation. These findings suggest that MLPH has anti-obesity and anti-hyperglycemic potential and could be effectively applied as a functional food ingredient or pharmaceutical.

ARHGAP21 is a RhoGAP protein implicated in the modulation of insulin secretion and energy metabolism. ARHGAP21 transient-inhibition increase glucose-stimulated insulin secretion (GSIS) in neonatal islets; however, ARHGAP21 heterozygote mice have a reduced insulin secretion. These discrepancies are not totally understood, and it might be related to functional maturation of beta cells and peripheral sensitivity. Here, we investigated the real ARHGAP21 role in the insulin secretion process using an adult mouse model of acute ARHGAP21 inhibition, induced by antisense. After ARHGAP21 knockdown induction by antisense injection in 60-day old male mice, we investigated glucose and insulin tolerance test, glucose-induced insulin secretion, glucose-induced intracellular calcium dynamics, and gene expression. Our results showed that ARHGAP21 acts negatively in the GSIS of adult islet. This effect seems to be due to the modulation of important points of insulin secretion process, such as the energy metabolism (PGC1α), Ca2+ signalization (SYTVII), granule-extrusion (SNAP25), and cell-cell interaction (CX36). Therefore, based on these finds, ARHGAP21 may be an important target in Diabetes Mellitus (DM) treatment.

The carbohydrate response element binding protein (ChREBP), a basic helix-loop-helix/leucine zipper transcription factor, plays a critical role in the control of lipogenesis in the liver. To identify the direct targets of ChREBP on a genome-wide scale and provide more insight into the mechanism by which ChREBP regulates glucose-responsive gene expression, we performed chromatin immunoprecipitation-sequencing and gene expression analysis. We identified 1153 ChREBP binding sites and 783 target genes using the chromatin from HepG2, a human hepatocellular carcinoma cell line. A motif search revealed a refined consensus sequence (CABGTG-nnCnG-nGnSTG) to better represent critical elements of a functional ChREBP binding sequence. Gene ontology analysis shows that ChREBP target genes are particularly associated with lipid, fatty acid and steroid metabolism. In addition, other functional gene clusters related to transport, development and cell motility are significantly enriched. Gene set enrichment analysis reveals that ChREBP target genes are highly correlated with genes regulated by high glucose, providing a functional relevance to the genome-wide binding study. Furthermore, we have demonstrated that ChREBP may function as a transcriptional repressor as well as an activator.

Rodents with mutations in the leptin, or leptin receptor, genes have been extensively used to investigate the regulation of energy balance and the factors that underlie the development of obesity. The excess energy gain of these mutants has long been considered as being due in part to increased metabolic efficiency, consequent to reduced energy expenditure, but this view has recently been challenged. We argue, particularly though not exclusively, from data on ob/ob mice, that three lines of evidence support the proposition that reduced expenditure is important in the aetiology of obesity in leptin pathway mutants (irrespective of the genetic background): (i) milk intake is similar in suckling ob/ob and +/? mice; (ii) ob/ob mice deposit excess energy when pair-fed to the ad libitum food intake of lean siblings; (iii) in several studies mutant mice have been shown to exhibit a lower RMR ‘per animal’ at temperatures below thermoneutrality. When metabolic rate is expressed ‘per unit body weight’ (inappropriately, because of body composition differences), then it is invariably lower in the obese than the lean. It is important to differentiate the causes from the consequences of obesity. Hyperphagic, mature obese animals weighing 2–3 times their lean siblings may well have higher expenditure ‘per animal’, reflecting the costs of being larger and of enhanced obligatory diet-induced thermogenesis resulting from the increased food intake. This cannot, however, be used to inform the aetiology of their obesity.

ARHGAP21 is a RhoGAP protein implicated in the modulation of insulin secretion and energy metabolism. ARHGAP21 transient-inhibition increase glucose-stimulated insulin secretion (GSIS) in neonatal islets; however, ARHGAP21 heterozygote mice have a reduced insulin secretion. These discrepancies are not totally understood, and it might be related to functional maturation of beta cells and peripheral sensitivity. Here, we investigated the real ARHGAP21 role in the insulin secretion process using an adult mouse model of acute ARHGAP21 inhibition, induced by antisense. After ARHGAP21 knockdown induction by antisense injection in 60-day old male mice, we investigated glucose and insulin tolerance test, glucose-induced insulin secretion, glucose-induced intracellular calcium dynamics, and gene expression. Our results showed that ARHGAP21 acts negatively in the GSIS of adult islet. This effect seems to be due to the modulation of important points of insulin secretion process, such as the energy metabolism (PGC1α), Ca2+ signalization (SYTVII), granule-extrusion (SNAP25), and cell-cell interaction (CX36). Therefore, based on these finds, ARHGAP21 may be an important target in Diabetes Mellitus (DM) treatment. [ABSTRACT FROM AUTHOR]

Background: Sulforaphane (SFN) is an isothiocyanate compound present in cruciferous vegetables. Although the anti-inflammatory effects of SFN have been reported, the precise mechanism related to the inflammatory genes is poorly understood. Objectives: This study examined the relationship between the anti-inflammatory effects of SFN and the differential gene expression pattern in SFN treated ob/ob mice. Methods: Nitric oxide (NO) level was measured using a Griess assay. The inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression levels were analyzed by Western blot analysis. Pro-inflammatory cytokines (tumor necrosis factor [TNF]-a, interleukin [IL]-1ß, and IL-6) were measured by enzyme-linked immunosorbent assay (ELISA). RNA sequencing analysis was performed to evaluate the differential gene expression in the liver of ob/ob mice. Results: The SFN treatment significantly attenuated the iNOS and COX-2 expression levels and inhibited NO, TNF-a, IL-1ß, and IL-6 production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. RNA sequencing analysis showed that the expression levels of 28 genes related to inflammation were up-regulated (> 2-fold), and six genes were down-regulated (< 0.6-fold) in the control ob/ob mice compared to normal mice. In contrast, the gene expression levels were restored to the normal level by SFN. The protein-protein interaction (PPI) network showed that chemokine ligand (Cxcl14, Ccl1, Ccl3, Ccl4, Ccl17) and chemokine receptor (Ccr3, Cxcr1, Ccr10) were located in close proximity and formed a "functional cluster" in the middle of the network. Conclusions: The overall results suggest that SFN has a potent anti-inflammatory effect by normalizing the expression levels of the genes related to inflammation that were perturbed in ob/ob mice. [ABSTRACT FROM AUTHOR]

Impaired insulin sensitivity of insulin-sensitive tissues plays a major role in the pathogenesis of type 2 diabetes, salvianolic acid B (SalB), a natural antioxidant usually treated various cardiovascular diseases was also reported potential utility on diabetes and dyslipidemia. Based on these, we aimed to explored whether the antioxidant effect of SalB play a pivotal role in the molecular mechanisms leading to insulin resistance. We found that SalB improved glucose tolerance and insulin sensitivity, decreased serum ALT, AST and ALP levels of ob/ob mice. Also, transcription of Bip and CHOP, phosphorylation of PERK and IRE1 for endoplasmic reticulum stress (ER) and phosphorylation of IRS-1 for insulin sensitivity in the liver of ob/ob mice were relieved by SalB. Further, SalB decreased phosphorylation of PERK, IRE1 and IRS1 and transcription of Bip and CHOP stimulated by palmitate of hepatic cells HL7702, but did not reversed phosphorylation of JNK and IRS1 and transcription of Bip and CHOP when ER stress was stimulated by tunicamycin. These data shows that SalB improved insulin resistance of ob/ob mice through suppression of hepatic ER stress. • An improvement of insulin resistance and glucose tolerance of ob/ob mice by salvianolic acid B (SalB) is explored. • The mechanism of SalB improving insulin resistance depends on the endopasmic reticulum stress is raised. • An extended application for a natural antioxidant SalB is confirmed. [ABSTRACT FROM AUTHOR]

Lack of leptin production in ob/ob mice results in obesity and prediabetes that could be partly reversed by leptin supplementation. In the hypothalamus, leptin supports the production of prolactin-releasing peptide (PrRP), an anorexigenic neuropeptide synthesized and active in the brain. In our recent studies, the palmitoylated PrRP analog palm11-PrRP31 showed a central anorexigenic effect after peripheral administration. This study investigates whether PrRP could compensate for the deficient leptin in ob/ob mice. In two separate experiments, palm11-PrRP31 (5 mg/kg) and leptin (5 or 10 µg/kg) were administered subcutaneously twice daily for 2 or 8 weeks to 8- (younger) or 16-(older) week-old ob/ob mice, respectively, either separately or in combination. The body weight decreasing effect of palm11-PrRP31 in both younger and older ob/ob mice was significantly powered by a subthreshold leptin dose, the combined effect could be then considered synergistic. Leptin and palm11-PrRP31 also synergistically lowered liver weight and blood glucose in younger ob/ob mice. Reduced liver weight was linked to decreased mRNA expression of lipogenic enzymes. In the hypothalamus of older ob/ob mice, two main leptin anorexigenic signaling pathways, namely, Janus kinase, signal transducer and activator of transcription-3 activation and AMP-activated protein kinase de-activation, were induced by leptin, palm11-PrRP31, and their combination. Thus, palm11-PrRP31 could partially compensate for leptin deficiency in ob/ob mice. In conclusion, the results demonstrate a synergistic effect of leptin and our lipidized palm11-PrRP31 analog. [ABSTRACT FROM AUTHOR]

Over the last few decades, there has been a significant increase in epidemiological studies suggesting that type 2 diabetes (T2DM) is linked to a higher risk of Alzheimer's disease (AD). However, how T2DM affects AD pathology, such as tau hyperphosphorylation, is not well understood. In this study, we investigated the impact of T2DM on tau phosphorylation in ob/ob mice, a spontaneous genetic model of T2DM.Tau phosphorylation at the AT8 epitope was slightly elevated in 4-week-old ob/ob mice while 26-week-old ob/ob mice exhibited tau hyperphosphorylation at multiple tau phospho-epitopes (Tau1, CP13, AT8, AT180, PHF1). We then examined the mechanism of tau hyperphosphorylation and demonstrated that it is mostly due to hypothermia, as ob/ob mice were hypothermic and normothermia restored tau phosphorylation to control levels. As caffeine has been shown to be beneficial for diabetes, obesity and tau phosphorylation, we, therefore, used it as therapeutic treatment. Unexpectedly, chronic caffeine intake exacerbated tau hyperphosphorylation by promoting deeper hypothermia.Our data indicate that tau hyperphosphorylation is predominately due to hypothermia consequent to impaired thermoregulation in ob/ob mice. This study establishes a novel link between diabetes and AD, and reinforces the importance of recording body temperature to better assess the relationship between diabetes and AD.

Introduction: Here, we investigated inflammatory signs of peripheral nerves in leptin-deficient obese ob/ob mice and the modulating effects of the exogenous iron load. Methods: Ob/ob and ob/+ control mice were fed with high, standard, or low iron diet for four months. Results: We found intraepidermal nerve fiber degeneration in foot skin and low-grade neuropathic abnormalities including mildly slowed motor and compound sensory nerve conduction velocities and low-grade macrophage and T-cell infiltration without overt neuropathology in sciatic nerves of all ob/ob mice. Low dietary iron load caused more pronounced abnormalities than high iron load in ob/ob mice. Discussion: Our data suggest that dietary non-heme iron deficiency may be a modulating factor in the pathogenesis of peripheral neuropathy in obese ob/ob mice with metabolic syndrome. Once the mechanisms can be further elucidated, how low dietary iron augments peripheral nerve degeneration and dysfunction via pro-inflammatory pathways and new therapeutic strategies could be developed. Abbreviations: CMAP: compound muscle action potential; cSNCV: compound sensory nerve conduction velocity; IENFD: intraepidermal nerve fiber density; LDL: low-density lipoprotein; MetS: metabolic syndrome; MNCV: motor conduction velocity; NCV: nerve conduction velocity; PN: peripheral neuropathy; PNS: peripheral nervous system; STZ: streptozotocin; T2D: type 2 diabetes mellitus; TNF alpha: tumor necrosis factor alpha; WHO: World Health Organization [ABSTRACT FROM AUTHOR]

Aims: Bone morphogenetic proteins (BMPs) are involved in the development and homeostasis of multiple organs and tissues. There has been a significant focus on understanding the role of BMPs in pancreatic β-cell dysfunction associated with type 2 diabetes (T2D). Our objective was to investigate the relationship between BMP6 and glucose homeostasis.Methods: Ob/ob mice were treated with BMP6 for 6 days and analyzed for insulin release, body weight, lipid parameters and glucose tolerance. Quantitative real-time PCR, chromatin immunoprecipitation and glucose output assays were used to assess BMP6 effect on gluconeogenesis in rat hepatoma H4IIE cells. Specificity of BMP6 receptors was characterized by the utilization of various receptor Fc fusion proteins in luciferase reporter gene and glucose output assays in INS1 and H4IIE cells.Results: Treatment of ob/ob mice with BMP6 for 6 days resulted in a reduction of circulating glucose and lipid levels, followed by a significantly elevated plasma insulin level in a dose-dependent manner. In addition, BMP6 improved the glucose excursion during an oral glucose tolerance test, lowering the total glycemic response by 21%. In rat H4IIE hepatoma cells, BMP6 inhibited gluconeogenesis and glucose output via downregulation the PepCK expression. Moreover, BMP6 inhibited glucose production regardless of the presence of cAMP, antagonizing its glycogenolytic effect. BMP6 acted on pancreatic and liver cells utilizing Alk3, Alk6 and ActRIIA serine/threonine kinase receptors.Conclusions: Collectively, we demonstrate that BMP6 improves glycaemia in T2D mice and regulates glucose metabolism in hepatocytes representing an exciting prospect for future treatments of diabetes. [ABSTRACT FROM AUTHOR]

Richard M Michelin,1 Layla Al-Nakkash,2 Tom L Broderick,3 Jeffrey H Plochocki4 1Arizona College of Osteopathic Medicine, 2Department of Physiology, 3Laboratory of Diabetes and Exercise Metabolism, Department of Physiology, 4Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, USA Background: Obesity and type 2 diabetes mellitus are associated with elevated risk of limb bone fracture. Incidences of these conditions are on the rise worldwide. Genistein, a phytoestrogen, has been shown by several studies to demonstrate bone-protective properties and may improve bone health in obese type 2 diabetics. Methods: In this study, we test the effects of genistein treatment on limb bone and growth plate cartilage histomorphometry in obese, hyperglycemic ob/ob mice. Six-week-old ob/ob mice were divided into control and genistein-treated groups. Genistein-treated mice were fed a diet containing 600 mg genistein/kg for a period of 4 weeks. Cross-sectional geometric and histomorphometric analyses were conducted on tibias. Results: Genistein-treated mice remained obese and hyperglycemic. However, histomorphometric comparisons show that genistein-treated mice have greater tibial midshaft diameters and ratios of cortical bone to total tissue area than the controls. Genistein-treated mice also exhibit decreased growth plate thickness of the proximal tibia. Conclusion: Our results indicate that genistein treatment affects bone of the tibial midshaft in the ob/ob mouse, independent of improvements in the hyperglycemic state and body weight. Keywords: obesity, hyperglycemia, genistein, ob/ob mice, bone

Background: The biological actions of various ginseng extracts have been studied for treating obesity and diabetes mellitus. However, few studies have evaluated the effects of fermented Korean Red Ginseng (Panax ginseng Meyer) on metabolic syndrome. The present study evaluated the antiobesity and antidiabetic effects of fermented red ginseng (FRG) on old-aged, obese, leptin-deficient (B6.V-Lepob, “ob/ob”) mice. Methods: The animals were divided into three groups and given water containing 0%, 0.5%, and 1.0% FRG for 16 wk. The effect of FRG on ob/ob mice was determined by measuring changes in body weight, levels of blood glucose, serum contents of triglycerides, total cholesterol and free fatty acids, messenger RNA (mRNA) expressions of key factors associated with insulin action, such as insulin receptor (IR), lipoprotein lipase (LPL), glucose transporter 1 and 4 (GLUT1 and GLUT4), peroxisome proliferators-activated receptor gamma (PPAR-γ), and phosphoenolpyruvate carboxykinase (PEPCK) in the liver and in muscle, and histology of the liver and pancreas. Results: FRG-treated mice had decreased body weight and blood glucose levels compared with control ob/ob mice. However, anti-obesity effect of FRG was not evident rather than hypoglycemic effect in old aged ob/ob mice. The hyperlipidemia in control group was attenuated in FRG-treated ob/ob mice. The mRNA expressions of IR, LPL, GLUT1, GLUT4, PPAR-γ, and PEPCK in the liver and in muscle were increased in the FRG-treated groups compared with the control group. Conclusion: These results suggest that FRG may play a vital role in improving insulin sensitivity relative to reducing body weight in old-aged ob/ob mice.

The sulfur-containing amino acid, taurine (Tau), regulates glucose and lipid homeostasis under normal, pre- and diabetic conditions. Here, we aimed to verify whether Tau supplementation exerts its beneficial effects against obesity, hyperglycemia and alterations in islet functions, in leptin-deficient obese (ob/ob), over a long period of treatment. From weaning until 12 months of age, female ob/ob mice received, or not, 5% Tau in drinking water (obTau group). After this period, a reduction in hypertriglyceridemia and an improvement in glucose tolerance and insulin sensitivity were observed in obTau mice. In addition, the daily metabolic flexibility was restored in obTau mice. In the gastrocnemius muscle of obTau mice, the activation of AMP-activated protein kinase (AMPK) was increased, while total AMPK protein content was reduced. Finally, isolated islets from obTau mice expressed high amounts of pyruvate carboxylase (PC) protein and lower glucose-induced insulin secretion. Taking these evidences together Tau supplementation had long-term positive actions on glucose tolerance and insulin sensitivity, associated with a reduction in glucose-stimulated insulin secretion, in ob/ob mice. The improvement in insulin actions in obTau mice was due, at least in part, to increased activation of AMPK in skeletal muscle, while the increased content of the PC enzyme in pancreatic islets may help to preserve glucose responsiveness in obTau islets, possibly contributing to islet cell survive. [ABSTRACT FROM AUTHOR]

Introduction. Obesity, hyperglycaemia, hyperlipidemia and hypertension are the hallmarks of metabolic syndrome. The epidemic of obesity has been accompanied by an analogous rise in the number of patients with metabolic syndrome. Thus, obesity and related metabolic disturbances are the main objective of public health throughout the world. Previously, we have shown that yohimbine, a non-selective α2-adrenergic receptor antagonist, reduces body weight and improves disrupted lipid and carbohydrates profiles in rats with diet-induced obesity. Material and method. In the presented study we have determined the effect of yohimbine on the body weight and carbohydrate and lipids levels in genetically obese leptin-deficient ob/ob mice and in lean C57BL6 mice. Results. Yohimbine had a favourable effect on elevated levels of triglycerides, cholesterol and glucose. However, it did not have any influence on body weight. Conclusions. The obtained data show that the weight reducing activity of yohimbine is primarily mediated via the interaction with α2-adrenergic receptor, and the subsequent enhanced release of noradrenaline which stimulates the β3-adrenergic receptor presented on adipocytes. The favourable influence of yohimbie on impaired lipid-carbohydrate homeostasis is achieved via the blockade of α1-adrenergic receptor. We believe that non-selective α-adrenoceptor antagonists might offer therapeutic benefits in the treatment of obesity and metabolic disturbances. [ABSTRACT FROM AUTHOR]

Since the discovery of the anti-diabetic effects of zinc (Zn) complex, we synthesized several Zn complexes and evaluated their effects using the KKAy type 2 diabetes mouse model. Recently, we demonstrated that organo-chalcogen (sulfur and selenium) Zn complexes elicit strong anti-diabetic effects. In this study, we treated leptin-deficient ob/ob mice with organo-chalcogen Zn complexes, and evaluated the resulting anti-diabetic effects in a mouse model of diabetes arising from pathogenic mechanisms different from those in KKAy mice. C57BL/6J ob/ob mice orally received either bis(3-hydroxy-2-methyl-4(H)-pyran-4-thiono)Zn, [Zn(hmpt)2] or bis(3-hydroxy-2-methyl-4(H)-pyran-4-seleno)Zn, [Zn(hmps)2], daily for 28 days. Both Zn complexes elicited potent blood glucose-lowering effects and improved HbA1c values. Moreover, glucose intolerance improved as evidenced by the oral glucose tolerance test, and fasting plasma insulin levels decreased in both types of Zn complex-treated mice. Zn concentrations in the liver and pancreas of [Zn(hmpt)2]-treated mice and in the pancreas of [Zn(hmps)2]-treated mice were increased, respectively. The results suggest that the present Zn complexes mainly exerted an anti-diabetic effect in the liver or pancreas. This study is the first to demonstrate that potent Zn complexes elicit anti-diabetic effects in not only KKAy but also ob/ob mice via a normalizing effect on insulin secretion and fasting blood glucose levels. [ABSTRACT FROM AUTHOR]

This narrative review addressed to both clinicians and researchers aims to assess the role of hypoleptinemia in disordered sleep with a particular focus on patients with anorexia nervosa (AN). After introducing circadian rhythms and the regulation of circulating leptin, we summarize the literature on disordered sleep in patients with AN and in fasting subjects in general. We highlight novel single-case reports of substantially improved sleep within days after initiation of off-label metreleptin treatment. These beneficial effects are set in relationship to current knowledge of disordered sleep in animal models of an impaired leptin signaling. Specifically, both absolute and relative hypoleptinemia play a major role in animal models for insomnia, obstructive sleep apnea and obesity hypoventilation syndrome. We pinpoint future research required to complement our understanding of the role of leptin in sleep in patients with acute AN. Moreover, within the section clinical applications we speculate that human recombinant leptin may be useful for the treatment of treatment-resistant sleep-wake disorders, which are associated with (relative) hypoleptinemia. Overall, we stress the role of the hormone leptin in sleep. • First time to assess the role of hypoleptinemia in disordered sleep in patients with AN. • First time to summarize the literature on disordered sleep in patients with AN and in fasting subjects in general. • Novel single case reports of substantially improved sleep after initiation of off-label metreleptin treatment. • Absolute and relative hypoleptinemia play a major role in animal models for insomnia, obstructive sleep apnea and obesity hypoventilation syndrome. • Medical hypothesis that human recombinant leptin may be useful for treatment resistant sleep disorders, associated with (relative) hypoleptinemia. [ABSTRACT FROM AUTHOR]

Mai Tong Fang (MTF), a Chinese herbal combination, has been used for the treatment of diabetic nephropathy in traditional medical clinics in China. However, the anti-adipogenic and anti-hyperglycemic effects of MTF have not been fully elucidated, so this study explored these pharmacological activities in 3T3-L1 adipocytes and ob/ob mice, respectively, of the water fraction of milkvetch root, salviae miltiorrhizae and mulberry as key components of MTF. MTF was found to inhibit adipogenesis and triglyceride accumulation in 3T3-L1 adipocytes. Oral administration of MTF in ob/ob mice for 8 weeks, exhibited positive controls on blood glucose and body weight, and further improved glucose tolerance according to an oral glucose tolerance test. Importantly, MTF extract alleviated fat deposition and ballooning degeneration in liver tissue and blocked the increase of adipocyte size in adipose tissue from treated ob/ob mice. These results indicated that the extract of key components in the traditional Chinese prescription MTF continue a potent anti-adipogenic and glucose-lowering agent.

Purpose: Cardiovascular (CV) diseases in type 2 diabetes (T2DM) represent an enormous burden with high mortality and morbidity. Sodium-glucose cotransporter 2 (SGLT2) inhibitors have recently emerged as a new antidiabetic class that improves glucose control, as well as body weight and blood pressure with no increased risk of hypoglycemia. The first CV outcome study terminated with empagliflozin, a specific SGLT2 inhibitor, has shown a reduction in CV mortality and in heart failure hospitalization, suggesting a beneficial impact on cardiac function which remains to be demonstrated. This study was designed to examine the chronic effect of empagliflozin on left ventricular (LV) systolic and diastolic functions in a genetic model of T2DM, ob/ob mice. Methods and Results: Cardiac phenotype was characterized by echocardiography, in vivo hemodynamics, histology, and molecular profiling. Our results demonstrate that empagliflozin significantly lowered HbA1c and slightly reduced body weight compared to vehicle treatment with no obvious changes in insulin levels. Empagliflozin also improved LV maximum pressure and in vivo indices of diastolic function. While systolic function was grossly not affected in both groups at steady state, response to dobutamine stimulation was significantly improved in the empagliflozin-treated group, suggesting amelioration of contractile reserve. This was paralleled by an increase in phospholamban (PLN) phosphorylation and increased SERCA2a/PLN ratio, indicative of enhanced SERCA2a function, further supporting improved cardiac relaxation and diastolic function. In addition, empagliflozin reconciled diabetes-associated increase in MAPKs and dysregulated phosphorylation of IRS1 and Akt, leading to improvement in myocardial insulin sensitivity and glucose utilization. Conclusion: The data show that chronic treatment with empagliflozin improves diastolic function, preserves calcium handling and growth signaling pathways and attenuates myocardial insulin resistance in ob/ob mice, findings suggestive of a potential clinical utility for empagliflozin in the treatment of diastolic dysfunction. [ABSTRACT FROM AUTHOR]

Leptin is an adipocyte-derived cytokine secreted mostly by adipose tissue. Serum leptin levels are elevated in obese individuals and correlate positively with body mass index (BMI). Interestingly, serum leptin levels are also elevated in patients with psoriasis and correlate positively with disease severity. Psoriasis is associated with obesity; patients with psoriasis have a higher incidence of obesity, and obese individuals have a higher risk of developing psoriasis. Additionally, obese patients with psoriasis experience a more severe degree of psoriasis. In this study, we hypothesised that leptin may link psoriasis and obesity and plays an aggravating role in psoriasis. To investigate leptin's role in psoriasis, we applied the widely accepted imiquimod (IMQ)-induced psoriasis-like skin inflammation mouse model on leptin-deficient ( ob/ob) mice and evaluated psoriasis severity. Moreover, we stimulated human keratinocytes with leptin and investigated the effect on proliferation and expression of pro-inflammatory proteins. In ob/ob mice, clinical signs of erythema, infiltration and scales in dorsal skin and inflammation in ear skin, as measured by ear thickness, were attenuated and compared with wt mice. Moreover, IL-17A and IL-22 mRNA expression levels, as well as increased epidermal thickness, were significantly less induced. In vitro, the effect of leptin stimulation on human keratinocytes demonstrated increased proliferation and induced secretion of several pro-inflammatory proteins; two hallmarks of psoriasis. In conclusion, leptin deficiency attenuated IMQ-induced psoriasis-like skin inflammation in a mouse model, and leptin stimulation induced a pro-inflammatory phenotype in human keratinocytes, thus, supporting an aggravating role of leptin in psoriasis. [ABSTRACT FROM AUTHOR]

Obesity is assumed to be a major cause of human essential hypertension; however, the mechanisms responsible for weight-related increase in blood pressure (BP) are not fully understood. The prevalence of hypertension induced by obesity has grown over the years, and the role of the renin-angiotensin-aldosterone system (RAAS) in this process continues to be elucidated. In this scenario, the ob/ob mice are a genetic obesity model generally used for metabolic disorder studies. These mice are normotensive even though they present several metabolic conditions that predispose them to hypertension. Although the normotensive trait in these mice is associated with the poor activation of sympathetic nervous system by the lack of leptin, we demonstrated that ob/ob mice present massively increased aminopeptidase A (APA) activity in the circulation. APA enzyme metabolizes angiotensin (ANG) II into ANG III, a peptide associated with intrarenal angiotensin type 2 (AT2) receptor activation and induction of natriuresis. In these mice, we found increased ANG-III levels in the circulation, high AT2 receptor expression in the kidney, and enhanced natriuresis. AT2 receptor blocking and APA inhibition increased BP, suggesting the ANG III-AT2 receptor axis as a complementary BP control mechanism. Circulating APA activity was significantly reduced by weight loss independently of leptin, indicating the role of fat tissue in APA production. Therefore, in this study we provide new data supporting the role of APA in BP control in ob/ob mouse strain. These findings improve our comprehension about obesity-related hypertension and suggest new tools for its treatment. [ABSTRACT FROM AUTHOR]

Over the last few decades, there has been a significant increase in epidemiological studies suggesting that type 2 diabetes (T2DM) is linked to a higher risk of Alzheimer's disease (AD). However, how T2DM affects AD pathology, such as tau hyperphosphorylation, is not well understood. In this study, we investigated the impact of T2DM on tau phosphorylation in ob/ob mice, a spontaneous genetic model of T2DM. Tau phosphorylation at the AT8 epitope was slightly elevated in 4-week-old ob/ob mice while 26-week-old ob/ob mice exhibited tau hyperphosphorylation at multiple tau phospho-epitopes (Tau1, CP13, AT8, AT180, PHF1). We then examined the mechanism of tau hyperphosphorylation and demonstrated that it is mostly due to hypothermia, as ob/ob mice were hypothermic and normothermia restored tau phosphorylation to control levels. As caffeine has been shown to be beneficial for diabetes, obesity and tau phosphorylation, we, therefore, used it as therapeutic treatment. Unexpectedly, chronic caffeine intake exacerbated tau hyperphosphorylation by promoting deeper hypothermia. Our data indicate that tau hyperphosphorylation is predominately due to hypothermia consequent to impaired thermoregulation in ob/ob mice. This study establishes a novel link between diabetes and AD, and reinforces the importance of recording body temperature to better assess the relationship between diabetes and AD. [ABSTRACT FROM AUTHOR]

Leptin, the product of the Ob(Lep) gene, is a peptide hormone that plays a major role in maintaining the balance between food intake and energy expenditure. In the brain, leptin receptors are expressed by hypothalamic cells but also in the olfactory bulb, the first central structure coding for odors, suggesting a precise function of this hormone in odor-evoked activities. Although olfaction plays a key role in feeding behavior, the ability of the olfactory bulb to integrate the energy-related signal leptin is still missing. Therefore, we studied the fate of odor-induced activity in the olfactory bulb in the genetic context of leptin deficiency using the obese ob/ob mice. By means of an odor discrimination task with concomitant local field potential recordings, we showed that ob/ob mice perform better than wild-type (WT) mice in the early stage of the task. This behavioral gain of function was associated in parallel with profound changes in neuronal oscillations in the olfactory bulb. The distribution of the peaks in the gamma frequency range was shifted toward higher frequencies in ob/ob mice compared to WT mice before learning. More notably, beta oscillatory activity, which has been shown previously to be correlated with olfactory discrimination learning, was longer and stronger in expert ob/ob mice after learning. Since oscillations in the olfactory bulb emerge from mitral to granule cell interactions, our results suggest that cellular dynamics in the olfactory bulb are deeply modified in ob/ob mice in the context of olfactory learning. [ABSTRACT FROM AUTHOR]

[Display omitted] • HM-chromanone is a potential active component that has anti-obesity effect in vivo. • HM-chromanone decreased body weight, fat size, fat mass, hepatic lipid accumulation and improved serum lipid profiles. • HM-chromanone decreased excessive lipid accumulation by activating AMPK. • HM-chromaone suppressed excessive lipid accumulation by downregulating adipogenic transcription factors and lipogenic enzymes. This study investigated whether HM-chromanone, a bioactive compound isolated from Portulaca oleracea L., inhibits lipid accumulation in adipose tissue and liver of C57BL/6J ob/ob mice. C57BL/6J mice were used for the normal group and C57BL/6J ob/ob mice were randomly divided into three groups: ob/ob, metformin and HM-chromanone. In the HM-chromanone group, body and liver weight, fat mass and fat size were significantly lower than that in the ob/ob group. The HM-chromanone group also showed lower serum lipid levels and hepatic lipid accumulation compared with the ob/ob group. HM-chromanone administration significantly activated adenosine monophosphate-activated protein kinase (AMPK) and inhibited sterol regulatory element binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) in adipose tissue and liver. These results suggest that HM-chromanone potentially suppresses lipid accumulation by modulating AMPK/SREBP-1c pathway in adipose tissue and liver of ob/ob mice. [ABSTRACT FROM AUTHOR]

Background: Nonalcoholic fatty liver disease (NAFLD) is the main reason for cirrhosis and hepatocellular carcinoma. As a starting point for NAFLD, the treatment of nonalcoholic fatty liver (NAFL) is receiving increasing attention. Mice fed a high-fat diet (HFD) and hereditary leptin deficiency (ob/ob) mice are important NAFL animal models. However, the comparison of these mouse models with human NAFL is still unclear., Methods: In this study, HFD-fed mice and ob/ob mice were used as NAFL animal models. Liver histopathological characteristics were compared, and liver transcriptome from both mouse models was performed using RNA sequencing (RNA-seq). RNA-seq data obtained from the livers of NAFL patients was downloaded from the GEO database. Global gene expression profiles in the livers were further analyzed using functional enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway., Results: Our results showed that the biochemical parameters of both mouse models and human NAFL were similar. Compared with HFD-fed mice, ob/ob mice were more similar in histologic appearance to NAFL patients. The liver transcriptome characteristics partly overlapped in mice and humans. Furthermore, in the NAFL pathway, most genes showed similar trends in mice and humans, thus demonstrating that both types of mice can be used as models for basic research on NAFL, considering the differences., Conclusion: Our findings show that HFD-fed mice and ob/ob mice can mimic human NAFL partly in pathophysiological process. The comparative analysis of liver transcriptome profile in mouse models and human NAFL presented here provides insights into the molecular characteristics across these NAFL models., (© 2023 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)