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The stomach acid degradation, mucus clearance and intestinal epithelial impermeability severely limit the oral delivery of polypeptide drugs. To simultaneously address the three major barriers, novel self-assembled core-shell nanosystems (CA-NPs) were designed. The fabricated shell of citric acid cross-linked carboxymethyl cellulose (CA-CMC) wrapped on core nanoparticles (HA-NPs) maintained the integrity of CA-NPs in the stomach. When CA-NPs passed through the stomach, the CA-CMC shell was gradually degraded to release the core HA-NPs in the intestine. HA-NPs with numerous hydrophilic groups and mannose side chains rapidly penetrated through the mucus layer and efficiently transcellular transported via the glucose transporter (GLUT)-mediated and paracellular transport through reversible opening of tight junctions (TJs) by CA-CMC. The oral bioavailability and therapeutic effects of CA-NPs-loaded polypeptide colistin against Escherichia coli (E. coli) bacteremia in mice were significantly increased compared with the native colistin, respectively. Good safety was observed following oral daily delivery for 14 consecutive days. Thus, CA-NPs may offer a promising strategy for the oral delivery of polypeptide drugs., Competing Interests: Declaration of Competing Interest The authors report no conflicts of interest in this work., (Copyright © 2022. Published by Elsevier B.V.)

The regulated translocation of the glucose transporter, GLUT4, to the surface of adipocytes and muscle is a key action of insulin. This is underpinned by the delivery and fusion of GLUT4-containing vesicles with the plasma membrane. Recent studies have revealed that a further action of insulin is to mediate the dispersal of GLUT4 molecules away from the site of GLUT4 vesicle fusion with the plasma membrane. Although shown in adipocytes, whether insulin-stimulated dispersal occurs in other cells and/or is exhibited by other proteins remains a matter of debate. Here we show that insulin stimulates GLUT4 dispersal in the plasma membrane of adipocytes, induced pluripotent stem cell-derived cardiomyocytes and HeLa cells, suggesting that this phenomenon is specific to GLUT4 expressed in all cell types. By contrast, insulin-stimulated dispersal of TfR was not observed in HeLa cells, suggesting that the mechanism may be unique to GLUT4. Consistent with dispersal being an important physiological mechanism, we observed that insulin-stimulated GLUT4 dispersal is reduced under conditions of insulin resistance. Adipocytes of different sizes have been shown to exhibit distinct metabolic properties: larger adipocytes exhibit reduced insulin-stimulated glucose transport compared to smaller cells. Here we show that both GLUT4 delivery to the plasma membrane and GLUT4 dispersal are reduced in larger adipocytes, supporting the hypothesis that larger adipocytes are refractory to insulin challenge compared to their smaller counterparts, even within a supposedly homogeneous population of cells., (© 2022. The Author(s).)

Natural compounds may bear promising therapeutic benefits against metabolic diseases such as type 2 diabetes mellitus (T2DM), which are characterized by a state of insulin resistance and mitochondrial dysfunction. Here, we examined the cellular mechanisms by which aspalathin, a dihydrochalcone C-glucoside unique to rooibos, may ameliorate palmitate-induced insulin resistance and mitochondrial dysfunction in cultured C2C12 myotubules. This current study demonstrated that aspalathin remains effective in improving glucose uptake in insulin-resistant skeletal muscle cells, supported by the upregulation of insulin-dependent signaling that involves the activation of insulin receptor (IR) and direct phosphorylation of protein kinase B (AKT). Interestingly, aspalathin also improved mitochondrial respiration and function, which was evident by an increased expression of carnitine palmitoyltransferase 1 (Cpt1), fatty acid transport protein 1 (Fatp1), sirtuin 1 (Sirt1), nuclear respiratory factor 1 (Nrf1), and transcription factor A, mitochondrial (Tfam). Importantly, our results showed that aspalathin treatment was effective in ameliorating the devastating outcomes of insulin resistance and mitochondrial dysfunction that are linked with an undesired pro-inflammatory response, by reducing the levels of well-known pro-inflammatory markers such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and protein kinase C-theta (PKC-theta). Thus, beyond improving glucose uptake and insulin signaling, the current study brings a new perspective in the therapeutic benefits of aspalathin in improving mitochondrial respiration and blocking inflammation to attenuate the detrimental effect of palmitate in skeletal muscle cells.

Epidemiologic studies have revealed that consuming green tea or coffee reduces diabetes risk. We evaluated the effects of the combined consumption of green tea catechins and coffee chlorogenic acids (GTC+CCA) on postprandial glucose, the insulin incretin response, and insulin sensitivity. Eleven healthy men were recruited for this randomized, double-blinded, placebo-controlled crossover trial. The participants consumed a GTC+CCA-enriched beverage (620 mg GTC, 373 mg CCA, and 119 mg caffeine/day) for three weeks; the placebo beverages (PLA) contained no GTC or CCA (PLA: 0 mg GTC, 0 mg CCA, and 119 mg caffeine/day). Postprandial glucose, insulin, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) responses were measured at baseline and after treatments. GTC+CCA consumption for three weeks showed a significant treatment-by-time interaction on glucose changes after the ingestion of high-fat and high-carbohydrate meals, however, it did not affect fasting glucose levels. Insulin sensitivity was enhanced by GCT+CCA compared with PLA. GTC+CCA consumption resulted in a significant increase in postprandial GLP-1 and a decrease in GIP compared to PLA. Consuming a combination of GTC and CCA for three weeks significantly improved postprandial glycemic control, GLP-1 response, and postprandial insulin sensitivity in healthy individuals and may be effective in preventing diabetes.

Arylamine N-acetyltransferase 2 (NAT2) is well-known for its role in phase II metabolism of xenobiotics and drugs. More recently, genome wide association studies and murine models implicated NAT2 in regulation of insulin sensitivity and plasma lipid levels. However, the mechanism remains unknown. Transcript levels of human NAT2 varied dynamically in HepG2 (hepatocellular) cells, depending on the nutrient status of the culture media. Culturing the cells in the presence of glucose induced NAT2 mRNA expression as well as its N-acetyltransferase activity significantly. In addition, insulin or acetate treatment also significantly induced NAT2 mRNA. We examined and compared the glucose- and acetate-dependent changes in NAT2 expression to those of genes involved in glucose and lipid metabolism, including FABP1, CPT1A, ACACA, SCD, CD36, FASN, ACLY, G6PC, and PCK1. Genes that are involved in fatty acid transport and lipogenesis, such as FABP1 and CD36, shared a similar pattern of expression with NAT2. In silico analysis of genes co-expressed with NAT2 revealed an enrichment of biological processes involved in lipid and cholesterol biosynthesis and transport. Among these, A1CF (APOBEC1 complementation factor) showed the highest correlation with NAT2 in terms of its expression in normal human tissues. The current study shows, for the first time, that human NAT2 is transcriptionally regulated by glucose and insulin in liver cancer cell lines and that the gene expression pattern of NAT2 is similar to that of genes involved in lipid metabolism and transport., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Stimuli-responsive hydrogels are an area of active discovery for approaches to deliver therapeutics in response to disease-specific indicators. Glucose-responsive delivery of insulin is of particular interest in better managing diabetes. Accordingly, hydrogels have been explored as platforms that enable both a rate and dose of insulin release aligning with the real-time physiological disease state; materials often include glucose sensing by dynamic-covalent cross-linking between phenylboronic acids (PBAs) and diols, with competition from ambient glucose reducing cross-link density of the material and accelerating release of encapsulated insulin. Yet, these materials historically have challenges with insulin leakage, offer limited glucose-responsive release of the insulin payload, and require unreasonably high injection pressures for syringe administration. Here, a thermogel platform prepared from temperature-induced micelles formed into a network by PBA-Diol cross-linking is optimized using a formulation-centered approach to maximize glucose-responsive insulin delivery. Importantly, the dual-responsive nature of this platform enables a low-viscosity sol at ambient temperature for facile injection, solidifying into a stable viscoelastic hydrogel network once in the body. The final optimized formulation affords acceleration in insulin release in response to glucose and enables single dose blood glucose control in diabetic rodents when subjected to multiple glucose challenges.

Background: The aim of the present study was to determine the role of individual PHLPP isoforms in insulin signaling and insulin resistance in neuronal cells., Methods: PHLPP isoforms were either silenced or overexpressed individually, and the effects were observed on individual Akt isoforms, AS160 and on neuronal glucose uptake, under insulin sensitive and resistant conditions. To determine PHLPP regulation itself, we tested effect of scaffold protein, Scribble, on PHLPP isoforms and neuronal glucose uptake., Results: We observed elevated expression of both PHLPP1 and PHLPP2 in insulin resistant neuronal cells (Neuro-2A, mouse neuroblastoma; SHSY-5Y, human neuroblastoma) as well as in the whole brain lysates of high-fat-diet mediated diabetic mice. In insulin sensitive condition, PHLPP isoforms differentially affected activation of all Akt isoforms, wherein PHLPP1 regulated serine phosphorylation of Akt2 and Akt3, while PHLPP2 regulated Akt1 and Akt3. This PHLPP mediated Akt isoform specific regulation activated AS160 affecting glucose uptake. Under insulin resistant condition, a similar trend of results were observed in Akt isoforms, AS160 and glucose uptake. Over-expressed PHLPP isoforms combined with elevated endogenous expression under insulin resistant condition drastically affected downstream signaling, reducing neuronal glucose uptake. No compensation was observed amongst PHLPP isoforms under all conditions tested, indicating independent roles and pointing towards possible scaffolding interactions behind isoform specificity. Silencing of Scribble, a scaffolding protein known to interact with PHLPP, affected cellular localization of both PHLPP1 and PHLPP2, and caused increase in glucose uptake., Conclusions: PHLPP isoforms play independent roles via Scribble in regulating Akt isoforms differentially, affecting AS160 and neuronal glucose uptake. Video abstract., (© 2022. The Author(s).)

Certain metabolic intermediates produced during metabolism are known to regulate a wide range of cellular processes. Methylglyoxal (MG), a natural metabolite derived from glycolysis, has been shown to negatively influence systemic metabolism by inducing glucose intolerance, insulin resistance, and diabetic complications. MG plays a functional role as a signaling molecule that initiates signal transduction. However, the specific relationship between MG-induced activation of signal transduction and its negative effects on metabolism remains unclear. Here, we found that MG activated mammalian target of rapamycin complex 1 (mTORC1) signaling via p38 mitogen-activated protein kinase in adipocytes, and that the transforming growth factor-β-activated kinase 1 (TAK1) is needed to activate p38-mTORC1 signaling following treatment with MG. We also found that MG increased the phosphorylation levels of serine residues in insulin receptor substrate (IRS)-1, which is involved in its negative regulation, thereby attenuating insulin-stimulated tyrosine phosphorylation in IRS-1. The negative effect of MG on insulin-stimulated IRS-1 tyrosine phosphorylation was exerted due to the MG-induced activation of the TAK1-p38-mTORC1 signaling axis. The involvement of the TAK1-p38-mTORC1 signaling axis in the induction of IRS-1 multiple serine phosphorylation was not unique to MG, as the proinflammatory cytokine, tumor necrosis factor-α, also activated the same signaling axis. Therefore, our findings suggest that MG-induced activation of the TAK1-p38-mTORC1 signaling axis caused multiple serine phosphorylation on IRS-1, potentially contributing to insulin resistance., (© 2022 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

The relaxin/insulin-like family peptide receptor 2 (RXFP2) belongs to the family of class A G-protein coupled receptors (GPCRs) and it is the only known target for the insulin-like factor 3 peptide (INSL3). The importance of this ligand-receptor pair in the development of the gubernacular ligament during the transabdominal phase of testicular descent is well established. More recently, RXFP2 has been implicated in maintaining healthy bone formation. In this report, we describe the discovery of a small molecule series of RXFP2 agonists. These compounds are highly potent, efficacious, and selective RXFP2 allosteric agonists that induce gubernacular invagination in mouse embryos, increase mineralization activity in human osteoblasts in vitro, and improve bone trabecular parameters in adult mice. The described RXFP2 agonists are orally bioavailable and display favorable pharmacokinetic properties, which allow for future evaluation of the therapeutic benefits of modulating RXFP2 activation in disease models., (© 2022. The Author(s).)

The inflammatory response plays critical important role in tissue hemostasis. Our previous study showed insulin-binding protein-5 (IGFBP5) could enhance the regeneration of tissue defect under inflammation condition, but the function of IGFBP5 in controlling inflammation and regulating immune responses remains unclear. In present study, we studied the regulatory effect of IGFBP5 on T cell immune response in vitro , and the maintenance of Th17/Treg balance in vivo by using dextran sulfate sodium salt (DSS)-induced colitis in mice. The results showed that IGFBP5 inhibited the differentiation of CD4 + T cells into Th17 subset while promoted its differentiation into Treg subsets. Further results of animal experiments demonstrated that recombinant IGFBP5 reversed the imbalance of Th17/Treg and alleviated the severity of DSS-induced colitis. The percentage of Th17 cells decreased and the percentage of Treg cells increased in the inflamed colon tissue and mesenteric lymph nodes of mice with colitis after IGFBP5 treatment. Besides, pro-inflammatory cytokines such as TNF-α, IL-1β and IFN-γ in serum were suppressed after the treatment of IGFBP5. Moreover, the function of IGFBP5 in regulating Th17/Treg balance could be inhibited by the inhibitors of ERK or JNK pathway. In conclusion, all these data showed that IGFBP5 could regulate Th17/Treg balance via ERK or JNK pathways. The findings of our study provide a theoretical basis for the application of IGFBP5 in inflammatory diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhu, Han, Hu, Cao and Fan.)

Pollen typhae, a traditional medicine in China, performs an anti-diabetic function and has anti-atherosclerosis effects involving suppression of vascular smooth muscle cell proliferation. However, the potential mechanisms keep to be revealed. The present study intended to investigate the influences of Pollen typhae extract named Pollen typhae total flavone (PTF) on A7r5 cell proliferation promoted by insulin and to uncover the underlying mechanisms. Proliferation and viability were evaluated by CCK-8 method. Western blotting was adopted to analyze the protein expression. Insulin promoted A7r5 cell proliferation, while PTF suppressed insulin-promoted proliferation in a concentration-dependent fashion. Although PTF did not change c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38MAPK) or MAPK kinase 1/2 (MEK1/2) protein expression and failed to affect the phosphorylation of JNK and p38MAPK, PTF remarkably inhibited extracellular signal-regulated kinase 1 and 2 (ERK1/2) protein expression and reduced ERK1/2 and MEK1/2 phosphorylation in A7r5 cells stimulated by insulin. Insulin-induced proliferation of A7r5 cells was abolished by inhibiting ERK1/2, which was in line with PTF. These findings indicate that PTF suppresses insulin-promoted proliferation of A7r5 cells involving the MEK1/2-ERK1/2 cascades, providing new insight into the potential uses of PTF for treatment of diabetic atherosclerosis.

Neurite outgrowth is a fundamental process in neurons that produces extensions and, consequently, neural connectivity. Neurite damage and atrophy are observed in various brain injuries and disorders. Understanding the intrinsic pathways of neurite outgrowth is essential for developing strategies to stimulate neurite regeneration. Insulin is a pivotal hormone in the regulation of glucose homeostasis. There is increasing evidence for the neurotrophic functions of insulin, including the induction of neurite outgrowth. However, the associated mechanism remains elusive. Here, we demonstrate that insulin potentiates neurite outgrowth mediated by the small GTPases ADP-ribosylation factor 6 (ARF6) and Ras-related C3 botulinum toxin substrate 1 (Rac1) through the neuronal adaptor FE65. Moreover, insulin enhances atypical protein kinase Cι/λ (PKCι/λ) activation and FE65 phosphorylation at serine 459 (S459) in neurons and mouse brains. In vitro and cellular assays show that PKCι/λ phosphorylated FE65 at S459. Consistently, insulin potentiates FE65 S459 phosphorylation only in the presence of PKCι/λ. Phosphomimetic studies show that an FE65 S459E mutant potently activates ARF6, Rac1, and neurite outgrowth. Notably, this phosphomimetic mutation enhances the FE65-ARF6 interaction, a process that promotes ARF6-Rac1-mediated neurite outgrowth. Likewise, insulin treatment and PKCι/λ overexpression potentiate the FE65-ARF6 interaction. Conversely, PKCι/λ knockdown suppresses the stimulatory effect of FE65 on ARF6-Rac1-mediated neurite outgrowth. The effect of insulin on neurite outgrowth is also markedly attenuated in PKCι/λ knockdown neurons, in the presence and absence of FE65. Our findings reveal a novel mechanism linking insulin with ARF6-Rac1-dependent neurite extension through the PKCι/λ-mediated phosphorylation of FE65., (© 2022 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

The main goal of this study was to investigate the molecular changes in pancreatic progenitor cells subject to high glucose, aspartame, and metformin in vitro. This scope of work glucose, aspartame, and metformin were exposed to pancreatic islet derived progenitor cells (PID-PCs) for 10 days. GLUT1's role in beta-cell differentiation was examined by using GLUT1 inhibitor WZB117. Insulin + cell ratio was measured by flow cytometry; the expression of beta-cell differentiation related genes was shown by RT-PCR; mitochondrial mass, mitochondrial ROS level, cytoplasmic Ca2 + , glucose uptake, and metabolite analysis were made fluorometrically and spectrophotometrically; and proteins involved in related molecular pathways were determined by western blotting. Findings showed that glucose or aspartame exposed cells had similar metabolic and gene expression profile to control PID-PCs. Furthermore, relatively few insulin + cells in aspartame treated cells were determined. Aspartame signal is transmitted through PLCβ2, CAMKK2 and LKB1 in PID-PCs. The most obvious finding of this study is that metformin significantly increased beta-cell differentiation. The mechanism involves suppression of the sweet taste signal's molecules T1R3, PLCβ2, cytoplasmic Ca +2 , and AKT in addition to the direct effect of metformin on mitochondria and AMPK, and the energy metabolism of PID-PCs is remodelled in the direction of oxidative phosphorylation. These findings are very important in terms of determining that metformin stimulates the mitochondrial remodeling and the differentiation of PID-PCs to beta-cells and thus it may contribute to the compensation step, which is the first stage of diabetes development., (© 2022. The Author(s) under exclusive licence to University of Navarra.)

Electrical signal controlled drug release from polymeric drug delivery system provides an efficient way for accurate and demandable drug release. In this work, insulin was loaded on inorganic nanoplates (layered double hydroxides, LDHs) and coated on a copper wire by co-electrodeposition with chitosan. The formed structure in chitosan composite hydrogel entrapped insulin efficiently, which were proved by various techniques. In addition, the drug loaded chitosan composite hydrogel demonstrated good biocompatibility as suggested by cell attachment. In vitro drug release experiment showed fast responsive pulsed release of insulin by biasing electrical signals. The in vivo experiment in diabetic rats revealed controllable insulin release in plasma and stable decrease of blood glucose can be achieved by using appropriate electrical signal. In addition, HE staining suggested negligible effect to the tissue by electrical signals. This work suggests that the electrical signal controlled insulin release from chitosan composited hydrogel may be a promising administration route for insulin., (© 2022 Wiley Periodicals LLC.)

Hypothermic (cold) preservation is a limiting factor for successful cell and tissue transplantation where cell swelling (edema) usually develops, impairing cell function. University of Wisconsin (UW) solution, a standard cold preservation solution, contains effective components to suppress hypothermia-induced cell swelling. Antifreeze proteins (AFPs) found in many cold-adapted organisms can prevent cold injury of the organisms. Here, the effects of a beetle AFP from Dendroides canadensis (DAFP-1) on pancreatic β-cells preservation were first investigated. As low as 500 µg/mL, DAFP-1 significantly minimized INS-1 cell swelling and subsequent cell death during 4 °C preservation in UW solution for up to three days. However, such significant cytoprotection was not observed by an AFP from Tenebrio molitor (TmAFP), a structural homologue to DAFP-1 but lacking arginine, at the same levels. The cytoprotective effect of DAFP-1 was further validated with the primary β-cells in the isolated rat pancreatic islets in UW solution. The submilligram level supplement of DAFP-1 to UW solution significantly increased the islet mass recovery after three days of cold preservation followed by rewarming. The protective effects of DAFP-1 in UW solution were discussed at a molecular level. The results indicate the potential of DAFP-1 to enhance cell survival during extended cold preservation.

The function of intracellular trafficking in immune-complex triggered inflammation remains poorly understood. Here, we investigated the role of Insulin-Regulated Amino Peptidase (IRAP)-positive endosomal compartments in Fc receptor (FcR)-induced inflammation. Less severe FcγR-triggered arthritis, active systemic anaphylaxis and FcεRI-triggered passive systemic anaphylaxis were observed in IRAP-deficient versus wild-type mice. In mast cells FcεRI stimulation induced rapid plasma membrane recruitment of IRAP-positive endosomes. IRAP-deficient cells exhibited reduced secretory responses, calcium signaling and activating Syk Y519/520 phosphorylation albeit receptor tyrosine phosphorylation on β and γ subunits was not different. By contrast, in the absence of IRAP, SHP1-inactivating phosphorylation on Ser 591 that controls Syk activity was decreased. Ex-vivo cell profiling after FcγR-triggered anaphylaxis confirmed decreased phosphorylation of both Syk Y519/520 and SHP-1 S591 in IRAP-deficient neutrophils and monocytes. Thus, IRAP-positive endosomal compartments, in promoting inhibition of SHP-1 during FcR signaling, control the extent of phosphorylation events at the plasma membrane and contribute to setting the intensity of immune-complex triggered inflammatory diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Bratti, Vibhushan, Longé, Koumantou, Ménasché, Benhamou, Varin-Blank, Blank, Saveanu and Ben Mkaddem.)

Circadian rhythms play a critical role in regulating metabolism, including daily cycles of feeding/fasting. Glucokinase (GCK) is central for whole-body glucose homeostasis and oscillates according to a circadian clock. GCK activators (GKAs) effectively reduce hyperglycemia, but their use is also associated with hypoglycemia, hyperlipidemia, and hepatic steatosis. Given the circadian rhythmicity and natural postprandial activation of GCK, we hypothesized that GKA treatment would benefit from being timed specifically during feeding periods. Acute treatment of obese Zucker rats with the GKA AZD1656 robustly increased flux into all major metabolic pathways of glucose disposal, enhancing glucose elimination. Four weeks of continuous AZD1656 treatment of obese Zucker rats improved glycemic control; however, hepatic steatosis and inflammation manifested. In contrast, timing AZD1656 to feeding periods robustly reduced hepatic steatosis and inflammation in addition to improving glycemia, whereas treatment timed to fasting periods caused overall detrimental metabolic effects. Mechanistically, timing AZD1656 to feeding periods diverted newly synthesized lipid toward direct VLDL secretion rather than intrahepatic storage. In line with increased hepatic insulin signaling, timing AZD1656 to feeding resulted in robust activation of AKT, mTOR, and SREBP-1C after glucose loading, pathways known to regulate VLDL secretion and hepatic de novo lipogenesis. In conclusion, intermittent AZD1656 treatment timed to feeding periods promotes glucose disposal when needed the most, restores metabolic flexibility and hepatic insulin sensitivity, and thereby avoids hepatic steatosis. Thus, chronotherapeutic approaches may benefit the development of GKAs and other drugs acting on metabolic targets.

Modelling insulin-glucose homeostasis may provide novel functional insights. In particular, simple models are clinically useful if they yield diagnostic methods. Examples include the homeostasis model assessment (HOMA) and the quantitative insulin sensitivity check index (QUICKI). However, limitations of these approaches have been criticised. Moreover, recent advances in physiological and biochemical research prompt further refinement in this area. We have developed a nonlinear model based on fundamental physiological motifs, including saturation kinetics, non-competitive inhibition, and pharmacokinetics. This model explains the evolution of insulin and glucose concentrations from perturbation to steady-state. Additionally, it lays the foundation of a structure parameter inference approach (SPINA), providing novel biomarkers of carbohydrate homeostasis, namely the secretory capacity of beta-cells (SPINA-GBeta) and insulin receptor gain (SPINA-GR). These markers correlate with central parameters of glucose metabolism, including average glucose infusion rate in hyperinsulinemic glucose clamp studies, response to oral glucose tolerance testing and HbA1c. Moreover, they mirror multiple measures of body composition. Compared to normal controls, SPINA-GR is significantly reduced in subjects with diabetes and prediabetes. The new model explains important physiological phenomena of insulin-glucose homeostasis. Clinical validation suggests that it may provide an efficient biomarker panel for screening purposes and clinical research., (© 2022. The Author(s).)

Alcohol use disorder (AUD) is a rapidly growing concern in the United States. Current trending escalations of alcohol use are associated with a concurrent rise in alcohol-related end-organ damage, increasing risk for further diseases. Alcohol-related end-organ damage can be driven by autonomic nervous system dysfunction, however studies on alcohol effects on autonomic control of end-organ function are lacking. Alcohol intake has been shown to reduce insulin secretions from the pancreas. Pancreatic insulin release is controlled in part by preganglionic parasympathetic motor neurons residing in the dorsal motor nucleus of the vagus (DMV) that project to the pancreas. How these neurons are affected by alcohol exposure has not been directly examined. Here we investigated the effects of acute ethanol (EtOH) application on DMV pancreatic-projecting neurons with whole-cell patch-clamp electrophysiology. We found that bath application of EtOH (50 mM) for greater than 30 min significantly enhanced the frequency of spontaneous inhibitory post synaptic current (sIPSC) events of DMV pancreatic-projecting neurons suggesting a presynaptic mechanism of EtOH to increase GABAergic transmission. Thirty-minute EtOH application also decreased action potential firing of these neurons. Pretreatment of DMV slices with 20 μM fluoxetine, a selective serotonin reuptake inhibitor, also increased GABAergic transmission and decreased action potential firing of these DMV neurons while occluding any further effects of EtOH application, suggesting a critical role for serotonin in mediating EtOH effects in the DMV. Ultimately, decreased DMV motor output may lead to alterations in pancreatic secretions. Further studies are needed to fully understand EtOH's influence on DMV neurons as well as the consequences of changes in parasympathetic output to the pancreas., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Ranolazine (Rn) is a drug used to treat persistent chronic coronary ischemia. It has also been shown to have therapeutic benefits on the central nervous system and an anti-diabetic effect by lowering blood glucose levels; however, no effects of Rn on cellular sensitivity to insulin (Ins) have been demonstrated yet. The present study aimed to investigate the permissive effects of Rn on the actions of Ins in astrocytes in primary culture. Ins (10 -8 M), Rn (10 -6 M), and Ins + Rn (10 -8 M and 10 -6 M, respectively) were added to astrocytes for 24 h. In comparison to control cells, Rn and/or Ins caused modifications in cell viability and proliferation. Rn increased protein expression of Cu/Zn-SOD and the pro-inflammatory protein COX-2 was upregulated by Ins. On the contrary, no significant changes were found in the protein expression of NF-κB and IκB. The presence of Rn produced an increase in p-ERK protein and a significant decrease in COX-2 protein expression. Furthermore, Rn significantly increased the effects of Ins on the expression of p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ. In addition, Rn + Ins produced a significant decrease in COX-2 expression. In conclusion, Rn facilitated the effects of insulin on the p-AKT, p-eNOS, p-ERK, Mn-SOD, and PPAR-γ signaling pathways, as well as on the anti-inflammatory and antioxidant effects of the hormone.

Congenital hyperinsulinism (CHI) is a rare genetic condition characterized by uncontrolled insulin secretion, resulting in hypoglycemia. Although glucagon has lately been regarded as a therapeutic option for CHI, its use is severely hampered by its poor solubility and stability at physiological pH, as well as its short duration of action. To address these constraints, we developed HM15136, a novel long-acting glucagon analog composed of a glucagon analog conjugated to the Fc fragment of human immunoglobulin G4 via a polyethylene glycol linker. In this study, we established that HM15136 was more soluble than natural glucagon (≥ 150 mg/mL vs 0.03 mg/mL). Next, we confirmed that HM15136 activated glucagon receptor in vitro and induced glycogenolysis and gluconeogenesis in rat primary hepatocytes. Pharmacokinetics (PK)/Pharmacodynamics (PD) analysis of HM15136 shows that HM15136 has a markedly longer half-life (36 h vs. < 5 min) and increased bioavailability (90%) compared to native glucagon in mice. Further, HM15136 could effectively reverse acute hypoglycemia induced by insulin challenge, and multiple doses of HM15136 could sustain increased blood glucose levels in CHI rats. In conclusion, our findings indicate that HM15136 promotes sustained elevation of blood glucose, demonstrating the potential for development as a once-weekly therapy for CHI., (© 2022. The Author(s).)

This study aimed to determine the postprandial effects of barley bread (BB) and oat bread (OB), grain sources of β-glucans, on glycaemia and appetite by comparison with white bread (WB) and whole-wheat bread (WWB). This randomized controlled crossover trial included 20 healthy individuals (10 males and 10 females) who consumed WB, WWB, BB, and OB with a standard breakfast followed by an ad libitum lunch. Postprandial glucose and appetite responses were quantified as the incremental area under the curve (iAUC). Although the iAUC for glycaemic response was lower by 23.7%, 29.9%, and 27.9% after the consumption of BB, OB, and WWB compared with WB ( p = 0.023), no differences were observed between BB, OB, and WWB ( p > 0.05). BB had a lower iAUC for appetite sensation by 21.5%, 23.9%, and 55.7% compared with WB, WWB, and OB ( p = 0.005). OB had no effect on appetite and was also less palatable than BB. Subsequent food intakes were similar after the consumption of all test breads ( p > 0.05). The encouragement of healthier bread formulations that can beneficially modulate postprandial glycemia and appetite may contribute to the promotion of public health. This trial was registered at ClinicalTrials.gov as NCT04749498.

A microdevice that offers glucagon supplements in a safe, non-invasive, and glucose-responsive manner is ideal for avoiding fatal hypoglycemia consequences from insulin overdosage during daily diabetes treatment. However, mold-assisted microfabrication of biomedical materials or devices typically needs high-resolution laser ablation to scale down structural design. In addition, the majority of the polymeric drug delivery materials being used to fabricate devices are dissolvable or deformable in aqueous environments, which restricts washing-based cleaning and purification procedures post shape fixation. This study leverages the design flexibility of 3D printing-assisted mold casting and presents a shrinking microfabrication approach that allows subsequent washing procedures to remove toxic monomer residues during polymerization. The feasibility of this approach is demonstrated by developing a glucose-responsive transdermal glucagon microneedle patch through matrix volume change-mediated release kinetic control. Shown in the type 1 diabetic mouse model, this transdermal patch can reverse the occurrence of hypoglycemia while lowering the risk of monomer residue-induced irritation during treatment. Freeing from the restrain of molding resolution for microstructure design, this shrinking methodology further provides an insight into post-fabrication purifications of biomedical materials., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

This is a secondary analysis of a randomized controlled trial (RCT) on the effects of the glucagon-like peptide-1 receptor agonists exenatide and insulin aspartate 30 injection on carotid intima-media thickness. Here, we report the renal outcomes of the intervention in patients with type 2 diabetes mellitus (T2DM). Data from the RCT study was used to evaluate the effect of exenatide or insulin given for 52 weeks on estimated glomerular filtration rate (eGFR) in patients with T2DM. The primary end point was the change in the eGFR from baseline between the exenatide and insulin groups in normal versus overweight patients and patients with obesity. The secondary end point was the correlation between change in eGFR and oxidative stress, glycemic control, and dyslipidemia. There was a significant difference in eGFR between the insulin and exenatide groups at 52 weeks (p=0.0135). Within the insulin group, the eGFR remained below baseline at 52 weeks in all patients, and there was an increase in body weight in the normal group compared with the overweight patients and patients with obesity. The opposite was observed in the exenatide group. A decrease in body weight was prominent in the exenatide group at 52 weeks (p<0.05), the eGFR was below baseline in overweight patients and patients with obesity and significantly above baseline in the normal group (p<0.05). The eGFR was positively correlated to 8-oxo-7,8-dihydroguanosine in the insulin group (p<0.05) but not the exenatide group. It can be concluded that compared with insulin, exenatide may improve renal function in overweight patients and patients with obesity more than in normal-weight patients with T2DM, but a further RCT is needed to confirm this effect., Competing Interests: Competing interests: None declared., (© American Federation for Medical Research 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Type 1 diabetes mellitus (T1DM) is a chronic and represented by insulin-causing pancreatic β-cell disruption and hyperglycemia. N-Acetyl-Cysteine (NAC) is regarded as facilitating endothelial cell function and angiogenesis and may have treatment effect in the case of diabetes. However, the impact of NAC on T1DM are unknown. Here we reported that inflammatory pathogenesis of canine type 1 diabetes liver disease and the therapeutic effect of NAC combined with insulin. For this purpose, the model was established by intravenous injection of streptozotocin (20 mg/kg). Forty adult dogs were used and divided into 5 groups: control group, DM group, insulin treatment group, NAC combined with insulin therapy, and NAC group, while study lasted for 16 weeks. Results showed that the level of liver function enzyme activity were apparently increased in DM group, while the NAC with insulin treatment remarkable decreased liver function enzyme levels. Histopathology revealed that obvious changes in liver structure of all DM group, as evidenced by hepatocyte disorder and cellular swelling. Liver structure was evaluated by Periodic Acid Schiff (PAS) and Masson staining, the tissues appeared glycogen deposition and collagen deposition, indicating that DM aggravated liver injury. Compared with control group, the protein and mRNA expression of NLRP3, Caspase-1, ASC, and GSDMD were significantly induced in the DM group, while INS and NAC combined with INS treatment reversed the above changes. The levels of NF-κB P65, p-NF-κB, and IFN γ were availably enhanced in the DM group, which decreased through insulin and NAC combined with insulin treatment. This study demonstrated that NAC combined with INS exerted protective effects against STZ-induced liver injury by inhibiting the NLRP3/NF-κB pathway. The findings indicated that NAC combined with INS may serve as a potential candidate therapy for the treatment of T1DM., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Long-term glucagon receptor (GCGR) agonism is associated with hyperglycemia and glucose intolerance, while acute GCGR agonism enhances whole-body insulin sensitivity and hepatic AKTSer473 phosphorylation. These divergent effects establish a critical gap in knowledge surrounding GCGR action. mTOR complex 2 (mTORC2) is composed of seven proteins, including RICTOR, which dictates substrate binding and allows for targeting of AKTSer473. We used a liver-specific Rictor knockout mouse (RictorΔLiver) to investigate whether mTORC2 is necessary for insulin receptor (INSR) and GCGR cross talk. RictorΔLiver mice were characterized by impaired AKT signaling and glucose intolerance. Intriguingly, RictorΔLiver mice were also resistant to GCGR-stimulated hyperglycemia. Consistent with our prior report, GCGR agonism increased glucose infusion rate and suppressed hepatic glucose production during hyperinsulinemic-euglycemic clamp of control animals. However, these benefits to insulin sensitivity were ablated in RictorΔLiver mice. We observed diminished AKTSer473 and GSK3α/βSer21/9 phosphorylation in RictorΔLiver mice, whereas phosphorylation of AKTThr308 was unaltered in livers from clamped mice. These signaling effects were replicated in primary hepatocytes isolated from RictorΔLiver and littermate control mice, confirming cell-autonomous cross talk between GCGR and INSR pathways. In summary, our study reveals the necessity of RICTOR, and thus mTORC2, in GCGR-mediated enhancement of liver and whole-body insulin action., (© 2022 by the American Diabetes Association.)

Insulin receptors are expressed throughout the adult brain, and insulin from the periphery reaches the central nervous system. In humans and rodents, actions of insulin in the brain decrease food intake. Furthermore, insulin receptor activation alters dopamine and glutamate transmission within mesolimbic regions that influence food-seeking and feeding including the nucleus accumbens (NAc). Here we determined how intra-NAc insulin affects conditioned approach (a measure of cue-triggered food-seeking), free food intake, and the motivation to obtain food in hungry rats using Pavlovian and instrumental approaches. Intra-NAc insulin did not affect conditioned approach but did reduce home cage chow intake immediately following conditioned approach testing. Consistent with reduced chow intake, intra-NAc insulin also reduced the motivation to work for flavored food pellets (assessed by a progressive ratio procedure). This effect was partially reversed by insulin receptor blockade and was not driven by insulin-induced sickness or malaise. Taken together, these data show that insulin within the NAc does not alter behavioral responses to a food cue, but instead reduces the motivation to work for and consume food in hungry animals. These data are discussed in light of insulin's role in the regulation of feeding, and its dysregulation by obesity., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Diabetes mellitus, a complex and heterogeneous disease associated with hyperglycemia, is a leading cause of mortality and reduces life expectancy. Vanadium complexes have been studied for the treatment of diabetes. The effect of complex [VO(bpy)(mal)]·H 2 O (complex A) was evaluated in a human hepatocarcinoma (HepG2) cell line and in streptozotocin (STZ)-induced diabetic male Wistar rats conditioned in seven groups with different treatments (n = 10 animals per group). Electron paramagnetic resonance and 51 V NMR analyses of complex A in high-glucose Dulbecco's Modified Eagle Medium (DMEM) revealed the oxidation and hydrolysis of the oxidovanadium(IV) complex over a period of 24 h at 37 °C to give low-nuclearity vanadates "V1" (H 2 VO 4 - ), "V2" (H 2 V 2 O 7 2- ), and "V4" (V 4 O 12 4- ). In HepG2 cells, complex A exhibited low cytotoxic effects at concentrations 2.5 to 7.5 μmol L -1 (IC 50 10.53 μmol L -1 ) and increased glucose uptake (2-NBDG) up to 93%, an effect similar to insulin. In STZ-induced diabetic rats, complex A at 10 and 30 mg kg -1 administered by oral gavage for 12 days did not affect the animals, suggesting low toxicity or metabolic impairment during the experimental period. Compared to insulin treatment alone, complex A (30 mg kg -1 ) in association with insulin was found to improve glycemia (30.6 ± 6.3 mmol L -1 vs. 21.1 ± 8.6 mmol L -1 , respectively; p = 0.002), resulting in approximately 30% additional reduction in glycemia. The insulin-enhancing effect of complex A was associated with low toxicity and was achieved via oral administration, suggesting the potential of complex A as a promising candidate for the adjuvant treatment of diabetes., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

BACKGROUNDInsulin resistance of the brain can unfavorably affect long-term weight maintenance and body fat distribution. Little is known if and how brain insulin sensitivity can be restored in humans. We aimed to evaluate the effects of an exercise intervention on insulin sensitivity of the brain and how this relates to exercise-induced changes in whole-body metabolism and behavior.METHODSIn this clinical trial, sedentary participants who were overweight and obese underwent an 8-week supervised aerobic training intervention. Brain insulin sensitivity was assessed in 21 participants (14 women, 7 men; age range 21-59 years; BMI range 27.5-45.5 kg/m2) using functional MRI, combined with intranasal administration of insulin, before and after the intervention.RESULTSThe exercise program resulted in enhanced brain insulin action to the level of a person of healthy weight, demonstrated by increased insulin-induced striatal activity and strengthened hippocampal functional connectivity. Improved brain insulin action correlated with increased mitochondrial respiration in skeletal muscle, reductions in visceral fat and hunger, as well as improved cognition. Mediation analyses suggest that improved brain insulin responsiveness helps mediate the peripheral exercise effects leading to healthier body fat distribution and reduced perception of hunger.CONCLUSIONOur study demonstrates that an 8-week exercise intervention in sedentary individuals can restore insulin action in the brain. Hence, the ameliorating benefits of exercise toward brain insulin resistance may provide an objective therapeutic target in humans in the challenge to reduce diabetes risk factors.TRIAL REGISTRATIONClinicalTrials.gov (NCT03151590).FUNDINGBMBF/DZD 01GI0925.

Background: Animal-fats are rich in long-chain saturated fatty-acids, well known to induct diabetic distress among ingested insulin-insensitive individuals. In the current-study, bovine-fat was fed to selective mice breeds highly sensitized to heavy dietary lipid load., Methods: The later high fat diet (HFD) group indeed undergone diabetic-onset within weeks with a drastically altered feed-behavior pattern. It consumed more food, gained body mass, elevated homeostatic model assessment value and extensively glycosylated Hb transporters., Results: However, the hypothetical test drug (Cuminaldehyde or CA) with known therapeutic-potential worked-well to balance food efficiency-ratio and Hb- counts closer to control. The fat-soluble phytochemical mono-terpenoid (CA) promoted constitutive mono-hexose (glucose) consuming catabolic-cycles via mono-glycoprotein (insulin) signal-transduction. It resolved diabetogenic-upsurge of gluconeogenic-enzymes, reduced non-sugar (amino/fatty acids) utilization by restricting transamination/dephosphorylation and restored liver-glycogen reserves near to normal-group effectively at 10 mg/kg b.w dose., Conclusions: Hence, the nutraceutical-potential (anti-diabetes/transaminitis ability) of administered exogenous redox-active agent CA can be entertained for evoking therapeutic-heath in diabetic human-community., (© 2022 The Author(s). Published by IMR Press.)

Insulin stimulates glucose uptake in adipocytes by triggering translocation of glucose transporter 4-containg vesicles to the plasma membrane. Under basal conditions, these vesicles (IRVs for insulin-responsive vesicles) are retained inside the cell via a "static" or "dynamic" mechanism. We have found that inhibitors of RNA and protein synthesis, actinomycin D and emetine, stimulate Glut4 translocation and glucose uptake in adipocytes without engaging conventional signaling proteins, such as Akt, TBC1D4, or TUG. Actinomycin D does not significantly affect endocytosis of Glut4 or recycling of transferrin, suggesting that it specifically increases exocytosis of the IRVs. Thus, the intracellular retention of the IRVs in adipocytes requires continuous RNA and protein biosynthesis de novo. These results point out to the existence of a short-lived inhibitor of IRV translocation thus supporting the "static" model., (© 2022. The Author(s).)

Obesity is a systemic disease and represents one of the leading causes of death worldwide by constituting the main risk factor for a series of non-communicable diseases such as type 2 diabetes mellitus (T2DM), cardiovascular diseases and dyslipidemia. Lifestyle interventions have been attempting to prevent T2DM and obesity but are difficult to maintain by most patients. However, the recent focus on the intestinal microbiota and its important role in the host's metabolism provides a new key for improving metabolic health. Modulating the composition of the gut microbiota was proposed as a method to manage these metabolic diseases and most frequently this is undertaken by using probiotics, prebiotics or synbiotics. Furthermore, the action of metformin, the most commonly prescribed drug for treating T2DM, is mediated in part by the gut microbiota, although this interplay may also be responsible for the frequent gastrointestinal adverse effects of metformin. Thus, adding a gut microbiota modulator (GMM), such as probiotics or prebiotics, to metformin therapy could amplify its anti-diabetic effects, while decreasing its adverse reactions. This review summarizes the various therapies that are used to shift the composition of the microbiome and their efficacy in alleviating metabolic parameters, it assesses the interaction between metformin and the gut microbiota, and it evaluates the existing clinical and preclinical studies that analyze the potential synergy of a combined metformin-GMM therapy.

Aims: Despite the high prevalence of diabetes in the world, its possible effects throughut pregnancy on neonatal auditory nervous system development are still unknown. In the present research, maternal diabetes' impact on the M2 and Adrenergic α2 receptors expression in the inferior colliculus (IC) of male newborn rats was investigated., Main Methods: Female rats were grouped into three: sham, insulin-treated diabetic, and diabetic. Diabetes was induced through streptozotocin (STZ) injection as one dose intraperitoneally (65 mg/kg). After mating and delivery, male rats were euthanized on P0, P7, and P14. Immunohistochemistry (IHC) was used to study the distribution pattern of receptors., Key Findings: The present study indicated that the expression of M2 receptors in the diabetic group was significantly increased in pairwise comparisons in the sham and diabetic treated with insulin groups (P < 0.001, each). The highest M2 expression was for the diabetic group on P14 and the lowest one was for the sham group on P0. The Adrenergic α2a receptors expression in the diabetic group was significantly reduced in pairwise comparisons in the sham and diabetic treated with insulin groups (P < 0.001, each). The highest Adrenergic α2a expression was for the sham group on P14 and the lowest one was for the diabetic group on P0. There was no significant difference between the sham and insulin groups regarding all receptors expression., Significance: This study demonstrated a time-dependent significant decrease in Adrenergic α2a but a time-dependent significant increase in M2 receptors expression., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Saturated free fatty acids (FFAs) such as palmitate in the circulation are known to cause endoplasmic reticulum (ER) stress and insulin resistance in peripheral tissues. In addition to protein kinase B (AKT) signaling, extracellular signal-regulated kinase (ERK) has been implicated in the development of insulin resistance. However, there are conflicting data regarding role of ERK signaling in ER stress-induced insulin resistance. In this study, we investigated the effects of ER stress on insulin resistance and ERK phosphorylation in Huh-7 cells and evaluated how oleate prevents palmitate-mediated ER stress. Treatment with insulin resulted in an increase of 38-45% in the uptake of glucose in control cells compared to non-insulin-treated control cells, along with an increase in the phosphorylation of AKT and ERK. We found that treatment with palmitate increased the expression of ER stress genes, including the splicing of X box binding protein 1 ( XBP1 ) mRNA. At the same time, we observed a decrease in insulin-mediated uptake of glucose and ERK phosphorylation in Huh-7 cells, without any change in AKT phosphorylation. Supplementation of oleate along with palmitate mitigated the palmitate-induced ER stress but did not affect insulin-mediated glucose uptake or ERK phosphorylation. The findings of this study suggest that palmitate reduces insulin-mediated ERK phosphorylation in liver cells and this effect is independent of fatty-acid-induced ER stress.

Background: We previously reported that modified extracellular-type trehalose-containing Kyoto (MK) solution, which contains a trypsin inhibitor (ulinastatin), significantly improved the islet yield compared with University of Wisconsin (UW) preservation, which is the gold standard for organ preservation for islet isolation. In this study, we evaluated the efficiency of a modified histidine-lactobionate (MHL) solution in addition to UW or MK solution. The MHL solution has a high sodium-low potassium composition with low viscosity compared with the UW solution. Moreover, similar to MK solution, MHL solution also contains ulinastatin., Methods: Porcine pancreata were preserved in UW, MK, or MHL solution, followed by islet isolation. An optimized number (1500 IE) of isolated islets from each group were then transplanted into streptozotocin-induced diabetic mice., Results: The islet yield before and after purification was significantly higher in the MHL group than in the UW group. On the contrary, the islet yield before and after purification was not significantly different between the MHL and MK groups. Preserving the porcine pancreata in MHL solution improved the outcome of islet transplantation in streptozotocin-induced diabetic mice compared with that in UW solution., Conclusions: Pancreas preservation with MHL solution preserves islet function better than UW solution. The effect of MHL solution is similar to that of MK solution, suggesting that MHL solution can be used as an alternative to MK solution for pancreatic islet transplantation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Adipose tissue is a key regulator of whole-body metabolic fitness because of its role in controlling insulin sensitivity. Obesity is associated with hypertrophic adipocytes with impaired glucose absorption, a phenomenon existing in the ultrarare monogenic disorder Alström syndrome consisting of severe insulin resistance. Inactivation of ALMS1 directly inhibits insulin-mediated glucose absorption in the white adipose tissue and induces severe insulin resistance, which leads to type 2 diabetes, accelerated nonalcoholic liver disease, and fibrosis. These phenotypes were reversed by specific adipocyte-ALMS1 reactivation in vivo. Subsequently, ALMS1 was found to bind to protein kinase C-α (PKCα) in the adipocyte, and upon insulin signaling, PKCα is released from ALMS1. α-Helices in the kinase domain of PKCα were therefore screened to identify a peptide sequence that interfered with the ALMS1-PKCα protein interaction. When incubated with cultured human adipocytes, the stapled peptide termed PATAS, for Peptide derived of PKC Alpha Targeting AlmS, triggered insulin-independent glucose absorption, de novo lipogenesis, and cellular glucose utilization. In vivo, PATAS reduced whole-body insulin resistance, and improved glucose intolerance, fasting glucose, liver steatosis, and fibrosis in rodents. Thus, PATAS represents a novel first-in-class peptide that targets the adipocyte to ameliorate insulin resistance and its associated comorbidities., (© 2022 by the American Diabetes Association.)

Sex differences in the prevalence and development of diabetes and associated cardiometabolic complications are well established. The objective of this study was to analyze the effects of estrogen on the maintenance of β-cell health/function and atherosclerosis progression, using a mouse model of hyperglycemia-induced atherosclerosis, the ApoE -/- : Ins2 +/Akita mouse. ApoE -/- : Ins2 +/Akita mice exhibit sexual dimorphism in the control of blood glucose levels. Male ApoE -/- : Ins2 +/Akita mice are chronically hyperglycemic due to a significant reduction in pancreatic β-cell mass. Female mice are only transiently hyperglycemic, maintain β-cell mass, and blood glucose levels normalize at 35 ± 1 days of age. To determine the effects of estrogen on pancreatic β-cell health and function, ovariectomies and estrogen supplementation experiments were performed, and pancreatic health and atherosclerosis were assessed at various time points. Ovariectomized ApoE -/- : Ins2 +/Akita mice developed chronic hyperglycemia with significantly reduced β-cell mass. To determine whether the observed effects on ovariectomized ApoE -/- : Ins2 +/Akita mice were due to a lack of estrogens, slow-releasing estradiol pellets were inserted subcutaneously. Ovariectomized ApoE -/- : Ins2 +/Akita mice treated with exogenous estradiol showed normalized blood glucose levels and maintained β-cell mass. Exogenous estradiol significantly reduced atherosclerosis in both ovariectomized female and male ApoE -/- : Ins2 +/Akita mice relative to controls. Together, these findings suggest that estradiol confers significant protection to pancreatic β-cell health and can directly and indirectly slow the progression of atherosclerosis. NEW & NOTEWORTHY This study examines the effect(s) of estrogen on β cell and cardiometabolic health/function in a novel mouse model of hyperglycemia-induced atherosclerosis ( ApoE -/- : Ins2 +/Akita ). Using a combination of estrogen deprivation (ovariectomy) and supplementation strategies, we quantify effects on glucose homeostasis and atherogenesis. Our results clearly show a protective role for estrogen on pancreatic β-cell health and function and glucose homeostasis. Furthermore, estrogen supplementation dramatically reduces atherosclerosis progression in both male and female mice.

Type 2 diabetes and obesity are associated with increased risk of cardiovascular disease, including heart failure. A hallmark of these dysmetabolic states is hyperinsulinemia and decreased cardiac reserve. However, the direct effects of hyperinsulinemia on myocardial function are incompletely understood. In this study, using invasive hemodynamics in mice, we studied the effects of short-term euglycemic hyperinsulinemia on basal myocardial function and subsequent responses of the myocardium to β-adrenergic stimulation. We found that cardiac function as measured by left ventricular (LV) invasive hemodynamics is not influenced by acute exposure to hyperinsulinemia, induced by an intravenous insulin injection with concurrent inotropic stimulation induced by β-adrenergic stimulation secondary to isoproterenol administration. When animals were exposed to 120-min of hyperinsulinemia by euglycemic-hyperinsulinemic clamps, there was a significant decrease in LV developed pressure, perhaps secondary to the systemic vasodilatory effects of insulin. Despite the baseline reduction, the contractile response to β-adrenergic stimulation remained intact in animals subject to euglycemic hyperinsulinemic clamps. β-adrenergic activation of phospholamban phosphorylation was not impaired by hyperinsulinemia. These results suggest that short-term hyperinsulinemia does not impair cardiac inotropic response to β-adrenergic stimulation in vivo., (© 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Discovery of interventions that delay or minimize age-related diseases is arguably the major goal of aging research. Conversely discovery of interventions based on phenotypic screens have often led to further elucidation of pathophysiological mechanisms. Although most hypotheses to explain lifespan focus on cell-autonomous processes, increasing evidence suggests that in multicellular organisms, neurons, particularly nutrient-sensing neurons, play a determinative role in lifespan and age-related diseases. For example, protective effects of dietary restriction and inactivation of insulin-like signaling increase lifespan and delay age-related diseases dependent on Creb-binding protein in GABA neurons, and Nrf2/Skn1 in just 2 nutrient-sensing neurons in C. elegans. Screens for drugs that increase lifespan also indicate that such drugs are predominantly active through neuronal signaling. Our own screens also indicate that neuroactive drugs also delay pathology in an animal model of Alzheimer's Disease, as well as inhibit cytokine production implicated in driving many age-related diseases. The most likely mechanism by which nutrient-sensing neurons influence lifespan and the onset of age-related diseases is by regulating metabolic architecture, particularly the relative rate of glycolysis vs. alternative metabolic pathways such as ketone and lipid metabolism. These results suggest that neuroactive compounds are a most promising class of drugs to delay or minimize age-related diseases., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Glycyrrhiza glabra roots have been well studied for their pharmacological activities, whereas less research has been conducted on liquorice aerial parts. Leaves represent a good source of D-pinitol, useful in the treatment of insulin resistance-related pathologies. Herein, we analyzed the in vitro effects of a D-pinitol-rich methanolic extract from Glycyrrhiza glabra leaves (GGLME) against lipotoxicity-related hypertrophy, inflammation, and insulin resistance in 3T3-L1 adipocytes exposed to palmitic acid (PA), comparing its activity with D-pinitol. GGLME pretreatment decreased lipid deposition, PPAR-γ, and NF-κB pathway induced by PA, similarly to D-pinitol, and improved insulin sensitivity, in presence or not of PA, increasing PI3K, pAkt, and GLUT1 levels. This study confirms that liquorice leaves, considered a waste of resource, could potentially be reused, and support further in vivo studies on animal and human models. In conclusion, liquorice leaves extract represents a potential candidate for prevention of metabolically induced inflammation, frequently leading to metabolic disorders.

Objective: To study the effects of exogenous calcium-load on promoting muscle-derived IL-6 secretion, and regulating AMPK and p38MAPK signal pathway to improve insulin resistance., Methods: C2C12 cell lines and palmitic acid-induced insulin resistance C2C12 cell lines were selected as the experimental objects. Preliminary experiment was aimed to determinate the glucose concentrations of culture solutions and observe contraction status of cells under microscope following different calcium concentrations culture 24 h. In the first official experiment, cells were divided into four groups: control group (A group, normal culture solution), IR group(B group, 0.6 mmol/L palmitic acid culture cells 24 h), 1 000 ng/ml IL-6 culture IR B group cells 48 h(IL-6+IR group) and IL-6 shRNA culture A group cells (IL-6shRNA group). In the second official experiment, cells were divided into three groups: IR group(A group), 100 μmol/L CaCl 2 culture IR group cells 48 h(CaCl 2 +IR group) and 100 μmol/L CaCl 2 and IL-6shRNA co- culture IR group cells 48 h(CaCl 2 +IL-6shRNA+IR group). The expression levels of GLUT4 mRNA and IL-6 mRNA were measured by real-time PCR, the protein expression levels of p-AMPK, p-p38MAPK, p-IRS-1 and p-PI-3K were measured by Western blot., Results: Preliminary experiment results showed that compared with 0 μmol/L CaCl 2 group, the glucose concentrations were decreased significantly after cells treated with CaCl 2 , at different concentrations. The cell contractions were observed under microscope and the cell contraction was most obvious treated with 100 μmol/L CaCl 2 . The first official experiment results showed that compared with IR group, the contents of p-AMP-activated protein kinase(p-AMPK), p-insulin receptor substrate 1(p-IRS-1), p-phosphoinositide-3 kinase(p-PI-3K), the expression level of glucose transporter 4(GLUT4) mRNA and the glucose uptake of IL-6+IR group were increased significantly( P ＜0.05 or P ＜0.01), the p-p38MAPK protein expression level was decreased significantly ( P ＜0.01) ; Compared with control group, the expression levels of p-AMPK, P-IRS-1, p-PI-3K, the expression level of GLUT4 mRNA and the glucose uptake of IL-6shRNA group were decreased significantly ( P ＜0.05 or P ＜0.01), the p-p38MAPK protein expression level was increased significantly ( P ＜0.01). The second official experiment results showed that compared with IR group, the expression levels of p-AMPK, P-IRS-1, p-PI-3K, the level of GLUT4 mRNA of CaCl 2 +IR group were increased significantly ( P ＜0.05 or P ＜0.01), the p-p38MAPK protein expression level was decreased significantly ( P ＜0.01); Compared with CaCl 2 +IR group, the contents of p-AMPK, P-IRS-1, p-PI-3K, the expression level of GLUT4 mRNA and the glucose uptake of CaCl 2 +IL-6 shRNA+IR group were decreased significantly ( P ＜0.05 or P ＜0.01), the p-p38MAPK protein expression level was increased significantly ( P ＜0.01)., Conclusion: Exogenous Ca-load can stimulate muscle cells contraction, and exercise-induced IL-6 improves insulin resistance by activating AMPK, PI-3Kand inhibiting p38MAPK signal pathway.

Objectives: In this study, we investigated whether scopoletin stimulated the secretion of insulin in pancreatic β cells as well as the underlying mechanism involved in this process., Methods: We incubated the INS-1 pancreatic β cells with various concentrations of glucose (1.1, 5.6 or 16.7 mM) in the presence or absence of scopoletin. We then analysed the secretion of insulin in the cells treated with insulin secretion inhibitors or secretagogues. The intracellular influx of calcium induced by scopoletin was also analysed using the Fluo-2 AM dye., Key Findings: We found that scopoletin (1-20 µM) markedly induced the secretion of insulin in a glucose concentration-dependent manner compared with the control. At depolarizing concentrations of potassium chloride (KCl), scopoletin markedly enhanced the insulin secretion compared with the cells which were treated only with KCl. Moreover, the treatment with diazoxide-opening K+ATP channel and verapamil blocking Ca2+ channel significantly decreased the scopoletin-induced increase in insulin secretion. After the pre-treatment of cells with a Ca2+ fluorescent dye, treatment with 20 µM scopoletin resulted in a significant increase in the influx of intracellular Ca2+, exhibiting fluorescence changes in various spectra., Conclusions: Scopoletin stimulates the secretion of insulin via a K+ATP channel-dependent pathway in the INS-1 pancreatic β cells., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Transplantation is lifesaving and the most effective treatment for end-stage organ failure. The transplantation success depends on the functional preservation of organs prior to transplantation. Currently, the University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) are the most commonly used preservation solutions. Despite intensive efforts, the functional preservation of solid organs prior to transplantation is limited to hours. In this study, we modified the UW solution containing components from both the UW and HTK solutions and analyzed their tissue-protective effect against ischemic injury. The composition of the UW solution was changed by reducing hydroxyethyl starch concentration and adding Histidine/Histidine-HCl which is the main component of HTK solution. Additionally, the preservation solutions were supplemented with melatonin and glucosamine. The protective effects of the preservation solutions were assessed by biochemical and microscopical analysis at 2, 10, 24, and 72 h after preserving the rat kidneys with static cold storage. Lactate dehydrogenase (LDH) activity in preservation solutions was measured at 2, 10, 24, and 72. It was not detectable at 2 h of preservation in all groups and 10 h of preservation in modified UW+melatonin (mUW-m) and modified UW+glucosamine (mUW-g) groups. At the 72nd hour, the lowest LDH activity (0.91 IU/g (0.63-1.17)) was measured in the mUW-m group. In comparison to the UW group, histopathological damage score was low in modified UW (mUW), mUW-m, and mUW-g groups at 10, 24, and 72 hours. The mUW-m solution at low temperature was an effective and suitable solution to protect renal tissue for up to 72 h., Competing Interests: The authors have declared that no competing interests exist.

Background: Type 2 diabetes (T2D) is characterized by a decreased insulin sensitivity. Magnesium (Mg 2+ ) deficiency is common in people with T2D. However, the molecular consequences of low Mg 2+ levels on insulin sensitivity and glucose handling have not been determined in adipocytes. The aim of this study is to determine the role of Mg 2+ in the insulin-dependent glucose uptake., Methods: First, the association of low plasma Mg 2+ with markers of insulin resistance was assessed in a cohort of 395 people with T2D. Secondly, the molecular role of Mg 2+ in insulin-dependent glucose uptake was studied by incubating 3T3-L1 adipocytes with 0 or 1 mmol/L Mg 2+ for 24 hours followed by insulin stimulation. Radioactive-glucose labelling, enzymatic assays, immunocytochemistry and live microscopy imaging were used to analyze the insulin receptor phosphoinositide 3-kinases/Akt pathway. Energy metabolism was assessed by the Seahorse Extracellular Flux Analyzer., Results: In people with T2D, plasma Mg 2+ concentration was inversely associated with markers of insulin resistance; i.e., the lower Mg 2+ , the more insulin resistant. In Mg 2+ -deficient adipocytes, insulin-dependent glucose uptake was decreased by approximately 50% compared to control Mg 2+ condition. Insulin receptor phosphorylation Tyr1150/1151 and PIP3 mass were not decreased in Mg 2+ -deficient adipocytes. Live imaging microscopy of adipocytes transduced with an Akt sensor (FoxO1-Clover) demonstrated that FoxO1 translocation from the nucleus to the cytosol was reduced, indicting less Akt activation in Mg 2+ -deficient adipocytes. Immunocytochemistry using a Lectin membrane marker and at the membrane located Myc epitope-tagged glucose transporter 4 (GLUT4) demonstrated that GLUT4 translocation was diminished in insulin-stimulated Mg 2+ -deficient adipocytes compared to control conditions. Energy metabolism in Mg 2+ deficient adipocytes was characterized by decreased glycolysis, upon insulin stimulation., Conclusions: Mg 2+ increases insulin-dependent glucose uptake in adipocytes and suggests that Mg 2+ deficiency may contribute to insulin resistance in people with T2D., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Oost, Kurstjens, Ma, Hoenderop, Tack and de Baaij.)

Critical functions of the blood-brain barrier (BBB), including cerebral blood flow, energy metabolism, and immunomodulation, are regulated by insulin signaling pathways. Therefore, endothelial insulin resistance could lead to BBB dysfunction, which is associated with neurodegenerative diseases such as Alzheimer's disease (AD). The current study aims to map the dynamics of insulin-responsive pathways in polarized human cerebral microvascular endothelial cell (hCMEC/D3) monolayers. RNA-Sequencing was performed on hCMEC/D3 monolayers with and without insulin treatment at various time points. The Short Time-series Expression Miner (STEM) method was used to identify gene clusters with distinct and representative expression patterns. Functional annotation and pathway analysis of genes from selected clusters were conducted using Webgestalt and Ingenuity Pathway Analysis (IPA) software. Quantitative expression differences of 16,570 genes between insulin-treated and control monolayers were determined at five-time points. The STEM software identified 12 significant clusters with 6880 genes that displayed distinct temporal patterns upon insulin exposure, and the clusters were further divided into three groups. Gene ontology (GO) enrichment analysis demonstrated that biological processes protecting BBB functions such as regulation of vascular development and actin cytoskeleton reorganization were upregulated after insulin treatment (Group 1 and 2). In contrast, GO pathways related to inflammation, such as response to interferon-gamma, were downregulated (Group 3). The IPA analyses further identified insulin-responsive cellular and molecular pathways that are associated with AD pathology. These findings unravel the dynamics of insulin action on the BBB endothelium and inform about downstream signaling cascades that are potentially disrupted due to brain insulin resistance prevalent in AD., (© 2022. The Author(s).)

Aims: Studies have observed changes in autophagic flux in the adipose tissue of type 2 diabetes patients with obesity. However, the role of autophagy in obesity-induced insulin resistance is unclear. We propose to confirm the effect of a high-fat diet (HFD) on autophagy and insulin signaling transduction from adipose tissue to clarify whether altered autophagy-mediated HFD induces insulin resistance, and to elucidate the possible mechanisms in autophagy-regulated adipose insulin sensitivity., Methods: Eight-week-old male C57BL/6 mice were fed with HFD to confirm the effect of HFD on autophagy and insulin signaling transduction from adipose tissue. Differentiated 3T3-L1 adipocytes were treated with 1.2 mM fatty acids (FAs) and 50 nM Bafilomycin A1 to determine the autophagic flux. 2.5 mg/kg body weight dose of Chloroquine (CQ) in PBS was locally injected into mouse epididymal adipose (10 and 24 h) and 40 µM of CQ to 3T3-L1 adipocytes for 24 h to evaluate the role of autophagy in insulin signaling transduction., Results: The HFD treatment resulted in a significant increase in SQSTM1/p62, Rubicon expression, and C/EBP homologous protein (CHOP) expression, yet the insulin capability to induce Akt (Ser473) and GSK3 β (Ser9) phosphorylation were reduced. PHLPP1 and PTEN remain unchanged after CQ injection. In differentiated 3T3-L1 adipocytes treated with CQ, although the amount of phospho-Akt stimulated by insulin in the CQ-treated group was significantly lower, CHOP expressions and cleaved caspase-3 were increased and bafilomycin A1 induced less accumulation of LC3-II protein., Conclusion: Long-term high-fat diet promotes insulin resistance, late-stage autophagy inhibition, ER stress, and apoptosis in adipose tissue. Autophagy suppression may not affect insulin signaling transduction via phosphatase expression but indirectly causes insulin resistance through ER stress or apoptosis., Competing Interests: The authors declare there are no competing interests., (©2022 Budi et al.)

In this study, the effects of cinnamaldehyde and curcumin on Akt2, a serine/threonine protein kinase central to the insulin signaling pathway, were examined in preadipocytes. Cinnamaldehyde or curcumin treatment increased Akt2 phosphorylation at multiple sites including T450 and Y475, but had no effect on Akt2 phosphorylation at S474, which is critical for Akt2 activation. Surprisingly, insulin treatment with cinnamaldehyde or curcumin increased p-Akt2 (S474) by 3.5-fold versus insulin treatment alone. Furthermore, combined cinnamaldehyde, curcumin, and insulin treatment increased p-Akt2 (S474) by 7-fold versus insulin treatment alone. Interestingly, cinnamaldehyde and curcumin inhibited both serine/threonine phosphatase 2A (PP2A) and protein tyrosine phosphatase 1B (PTP1B). Akt2 activation is a multistep process that requires phosphorylation at T450 for proper folding and maturation, and phosphorylation of both Y475 and S474 for stabilization of the catalytic domain. It is plausible that by inhibiting PP2A and PTP1B, cinnamaldehyde and curcumin increase phosphorylation at T450 and Y475, and prime Akt2 for insulin-stimulated phosphorylation at S474. Notably, the combination of a PP2A inhibitor, okadaic acid, and a PTP1B inhibitor increased p-Akt2 (S474), even in the absence of insulin. Future combinations of PP2A and PTP1B inhibitors provide a rational platform to engineer new therapeutics for insulin resistance syndrome.

Background/aim: Lipopolysaccharide (LPS) is thought to be a causative agent of type 2 diabetes, because it has been shown that a single LPS stimulation in vitro induces chronic inflammation and reduces insulin signaling in adipocytes. However, oral LPS administration prevents type 2 diabetes, and this effect does not correspond to a single LPS adipocyte stimulation. In this study, the response of adipocytes to single and repeated stimulation with LPS was examined., Materials and Methods: 3T3-L1 cells were differentiated into adipocytes and stimulated with LPS once or thrice every 24 h. The expression levels of inflammatory and anti-inflammatory factors and insulin sensitivity-related factors were measured., Results: Single stimulation with LPS increased the mRNA and protein expression of inflammatory factors (interleukin-6 and monocyte chemotactic protein 1), but this increase was inhibited by repeated stimulation. In contrast, the mRNA expression levels of anti-inflammatory factors (proliferator-activated receptor γ and peroxisome proliferator-activated receptor gamma coactivator1 α) were increased by repeated LPS stimulation. Additionally, the mRNA expression levels of insulin sensitivity-related factors (glucose transporter type 4, insulin receptor, insulin receptor substrate 1 and thymoma viral proto-oncogene 2) in adipocytes were increased upon repeated LPS stimulation., Conclusion: Repetitive LPS stimulation, unlike single stimulation of adipocytes, upregulates anti-inflammatory and insulin signaling-related factors., (Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The ventromedial hypothalamic (VMH) nucleus is a well-established hub for energy and glucose homeostasis. In particular, VMH neurons are thought to be important for initiating the counterregulatory response to hypoglycemia, and ex vivo electrophysiology and immunohistochemistry data indicate a clear role for VMH neurons in sensing glucose concentration. However, the temporal response of VMH neurons to physiologically relevant changes in glucose availability in vivo has been hampered by a lack of available tools for measuring neuronal activity over time. Since the majority of neurons within the VMH are glutamatergic and can be targeted using the vesicular glutamate transporter Vglut2, we expressed cre-dependent GCaMP7s in Vglut2 cre mice and examined the response profile of VMH to intraperitoneal injections of glucose, insulin, and 2-deoxyglucose (2DG). We show that reduced available glucose via insulin-induced hypoglycemia and 2DG-induced glucoprivation, but not hyperglycemia induced by glucose injection, inhibits VMH Vglut2 neuronal population activity in vivo. Surprisingly, this inhibition was maintained for at least 45 minutes despite prolonged hypoglycemia and initiation of a counterregulatory response. Thus, although VMH stimulation, via pharmacological, electrical, or optogenetic approaches, is sufficient to drive a counterregulatory response, our data suggest VMH Vglut2 neurons are not the main drivers required to do so, since VMH Vglut2 neuronal population activity remains suppressed during hypoglycemia and glucoprivation., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)