Adipose-specific overexpression of GLUT4 reverses insulin resistance and diabetes in mice lacking GLUT4 selectively in muscle

Adipose tissue plays an important role in glucose homeostasis and affects insulin sensitivity in other tissues. In obesity and type 2 diabetes, glucose transporter 4 (GLUT4) is downregulated in adipose tissue, and glucose transport is also impaired in muscle. To determine whether overexpression of GLUT4 selectively in adipose tissue could prevent insulin resistance when glucose transport is impaired in muscle, we bred muscle GLUT4 knockout (MG4KO) mice to mice overexpressing GLUT4 in adipose tissue (AG4Tg). Overexpression of GLUT4 in fat not only normalized the fasting hyperglycemia and glucose intolerance in MG4KO mice, but it reduced these parameters to below normal levels. Glucose infusion rate during a euglycemic clamp study was reduced 46% in MG4KO compared with controls and was restored to control levels in AG4Tg-MG4KO. Similarly, insulin action to suppress hepatic glucose production was impaired in MG4KO mice and was restored to control levels in AG4Tg-MG4KO. 2-deoxyglucose uptake during the clamp was increased approximately twofold in white adipose tissue but remained reduced in skeletal muscle of AG4Tg-MG4KO mice. AG4Tg and AG4Tg-MG4KO mice have a slight increase in fat mass, a twofold elevation in serum free fatty acids, an approximately 50% increase in serum leptin, and a 50% decrease in serum adiponectin. In MG4KO mice, serum resistin is increased 34% and GLUT4 overexpression in fat reverses this. Overexpression of GLUT4 in fat also reverses the enhanced clearance of an oral lipid load in MG4KO mice. Thus overexpression of GLUT4 in fat reverses whole body insulin resistance in MG4KO mice without restoring glucose transport in muscle. This effect occurs even though AG4Tg-MG4KO mice have increased fat mass and low adiponectin and is associated with normalization of elevated resistin levels.     

Caveolin-1-deficient mice show insulin resistance and defective insulin receptor protein expression in adipose tissue

Several lines of evidence suggest that a functional relationship exists between caveolin-1 and insulin signaling. However, it remains unknown whether caveolin-1 is normally required for proper insulin receptor signaling in vivo. To address this issue, we examined the status of insulin receptor signaling in caveolin-1 (–/–)-deficient (Cav-1 null) mice. Here, we show that Cav-1 null mice placed on a high-fat diet for 9 mo develop postprandial hyperinsulinemia. An insulin tolerance test (ITT) revealed that young Cav-1 null mice on a normal chow diet are significantly unresponsive to insulin, compared with their wild-type counterparts. This insulin resistance is due to a primary defect in adipose tissue, as evidenced by drastically reduced insulin receptor protein levels (>90%), without any changes in insulin receptor mRNA levels. These data suggest that caveolin-1 acts as a molecular chaperone that is necessary for the proper stabilization of the insulin receptor in adipocytes in vivo. In support of this notion, we demonstrate that recombinant expression of caveolin-1 in Cav-1 null mouse embryo fibroblasts rescues insulin receptor protein expression. These data provide evidence that the lean body phenotype observed in the Cav-1 knockout mice is due, at least in part, to a defect in insulin-regulated lipogenesis. caveolae; caveolin; insulin signaling; protein stabilization; knockout mice     

(+)-Rutamarin as a dual inducer of both GLUT4 translocation and expression efficiently ameliorates glucose homeostasis in insulin-resistant mice

Glucose transporter 4 (GLUT4) is a principal glucose transporter in response to insulin, and impaired translocation or decreased expression of GLUT4 is believed to be one of the major pathological features of type 2 diabetes mellitus (T2DM). Therefore, induction of GLUT4 translocation or/and expression is a promising strategy for anti-T2DM drug discovery. Here we report that the natural product (+)-Rutamarin (Rut) functions as an efficient dual inducer on both insulin-induced GLUT4 translocation and expression. Rut-treated 3T3-L1 adipocytes exhibit efficiently enhanced insulin-induced glucose uptake, while diet-induced obese (DIO) mice based assays further confirm the Rut-induced improvement of glucose homeostasis and insulin sensitivity in vivo. Subsequent investigation of Rut acting targets indicates that as a specific protein tyrosine phosphatase 1B (PTP1B) inhibitor Rut induces basal GLUT4 translocation to some extent and largely enhances insulin-induced GLUT4 translocation through PI3 kinase-AKT/PKB pathway, while as an agonist of retinoid X receptor α (RXRα), Rut potently increases GLUT4 expression. Furthermore, by using molecular modeling and crystallographic approaches, the possible binding modes of Rut to these two targets have been also determined at atomic levels. All our results have thus highlighted the potential of Rut as both a valuable lead compound for anti-T2DM drug discovery and a promising chemical probe for GLUT4 associated pathways exploration.     

Hydroxytyrosol ameliorates insulin resistance by modulating endoplasmic reticulum stress and prevents hepatic steatosis in diet-induced obesity mice

Endoplasmic reticulum (ER) is a principal organelle responsible for energy and nutrient management. Its dysfunction has been viewed in the context of obesity and related glucolipid metabolic disorders. However, therapeutic approaches to improve ER adaptation and systemic energy balance in obesity are limited. Thus, we examined whether hydroxytyrosol (HT), an important polyphenolic compound found in virgin olive oil, could correct the metabolic impairments in diet-induced obesity (DIO) mice. Here, we found that HT gavage for 10 weeks significantly ameliorated glucose homeostasis and chronic inflammation and decreased hepatic steatosis in DIO mice. At the molecular level, ER stress indicators, inflammatory and insulin signaling markers demonstrated that high-fat diet (HFD)-induced ER stress and insulin resistance (IR) in insulin sensitive tissue were corrected by HT. In vitro studies confirmed that HT supplementation (100 μM) attenuated palmitate-evoked ER stress, thus rescuing the downstream JNK/IRS pathway. As a result from suppression of ER stress in the liver, HT further decreased hepatic sterol regulatory element-binding protein-1 expression (SREBP1). Additionally, aberrant expression of genes involved in hepatic lipogenesis (SREBP1, ACC, FAS, SCD1) caused by HFD was restored by HT. These findings suggested that HT ameliorated chronic inflammation and IR and decreased hepatic steatosis in obesity by beneficial modulation of ER stress.     

A role of lipin in human obesity and insulin resistance: relation to adipocyte glucose transport and GLUT4 expression

The mouse lipin gene, Lpin1, is important for adipose tissue development and is a candidate gene for insulin resistance. Here, we investigate the adipose tissue expression levels of the human LPIN1 gene in relation to various clinical variables as well as adipocyte function. LPIN1 gene expression was induced at an early step in human preadipocyte differentiation in parallel with peroxisome proliferator-activated receptor gamma. Lipin mRNA levels were higher in fat cells than in adipose tissue segments but showed no difference between subcutaneous and omental depots. Moreover, LPIN1 expression levels were reduced in obesity, improved following weight reduction in obese subjects, and were downregulated in women with the metabolic syndrome. With respect to adipocyte function, adipose LPIN1 gene expression was strongly associated with both basal and insulin-mediated subcutaneous adipocyte glucose transport as well as mRNA levels of glucose transporter 4 (GLUT4). We show that body fat accumulation is a major regulator of human adipose LPIN1 expression and suggest a role of LPIN1 in human preadipocyte as well as mature adipocyte function.     

GLUT4 and UBC9 protein expression is reduced in muscle from type 2 diabetic patients with severe insulin resistance

Aims

Subgroups of patients with type 2 diabetes mellitus demand large insulin doses to maintain euglycemia. These patients are characterized by severe skeletal muscle insulin resistance and the underlying pathology remains unclear. The purpose of this study was to examine protein expression of the principal glucose transporter, GLUT4, and associated proteins in skeletal muscle from type 2 diabetic patients characterized by severe insulin resistance.

Methods

Seven type 2 diabetic patients with severe insulin resistance (mean insulin dose 195 IU/day) were compared with seven age matched type 2 diabetic patients who did not require insulin treatment, and with an age matched healthy control group. Protein expression of GLUT4 and associated proteins was assessed in muscle and fat biopsies using standard western blotting techniques.

Results

GLUT4 protein expression was significantly reduced by ∼30 pct in skeletal muscle tissue from severely insulin resistant type 2 diabetic subjects, compared with both healthy controls and type 2 diabetic subjects that did not require insulin treatment. In fat tissue, GLUT4 protein expression was reduced in both diabetic groups. In skeletal muscle, the reduced GLUT4 expression in severe insulin resistance was associated with decreased ubiquitin-conjugating enzyme 9 (UBC9) expression while expression of GLUT1, TBC1D1 and AS160 was not significantly different among type 2 diabetic patients and matched controls.

Conclusions

Type 2 diabetic patients with severe insulin resistance have reduced expression of GLUT4 in skeletal muscle compared to patients treated with oral antidiabetic drugs alone. GLUT4 protein levels may therefore play a role in the pathology behind type 2 diabetes mellitus among subgroups of patients, and this may explain the heterogeneous response to insulin treatment. This new finding contributes to the understanding of the underlying mechanisms for the development of extreme insulin resistance.     

Increased adiposity in DNA binding-dependent androgen receptor knockout male mice associated with decreased voluntary activity and not insulin resistance

In men, as testosterone levels decrease, fat mass increases and muscle mass decreases. Increased fat mass in men, in particular central obesity, is a major risk factor for type 2 diabetes, cardiovascular disease, and all-cause mortality. Testosterone treatment has been shown to decrease fat mass and increase fat-free mass. We hypothesize that androgens act directly via the DNA binding-dependent actions of the androgen receptor (AR) to regulate genes controlling fat mass and metabolism. The aim of this study was to determine the effect of a global DNA binding-dependent (DBD) AR knockout (DBD-ARKO) on the metabolic phenotype in male mice by measuring body mass, fat mass, food intake, voluntary physical activity, resting energy expenditure, substrate oxidation rates, serum glucose, insulin, lipid, and hormone levels, and metabolic gene expression levels and second messenger protein levels. DBD-ARKO males have increased adiposity despite a decreased total body mass compared with wild-type (WT) males. DBD-ARKO males showed reduced voluntary activity, decreased food intake, increased serum leptin and adiponectin levels, an altered lipid metabolism gene profile, and increased phosphorylated CREB levels compared with WT males. This study demonstrates that androgens acting via the DNA binding-dependent actions of the AR regulate fat mass and metabolism in males and that the increased adiposity in DBD-ARKO male mice is associated with decreased voluntary activity, hyperleptinemia and hyperadiponectinemia and not with insulin resistance, increased food intake, or decreased resting energy expenditure.     

Soybean and sunflower oil‐induced insulin resistance correlates with impaired GLUT4 protein expression and translocation specifically in white adipose tissue

Free fatty acids are known for playing a crucial role in the development of insulin resistance. High fat intake is known for impairing insulin sensitivity; however, the effect of vegetable‐oil injections have never been investigated. The present study investigated the effects of daily subcutaneous injections (100 µL) of soybean (SB) and sunflower (SF) oils, during 7 days. Both treated groups developed insulin resistance as assessed by insulin tolerance test. The mechanism underlying the SB‐ and SF‐induced insulin resistance was shown to involve GLUT4. In SB‐ and SF‐treated animals, the GLUT4 protein expression was reduced ～20% and 10 min after an acute in vivo stimulus with insulin, the plasma membrane GLUT4 content was ～60% lower in white adipose tissue (WAT). No effects were observed in skeletal muscle. Additionally, both oil treatments increased mainly the content of palmitic acid (～150%) in WAT, which can contribute to explain the GLUT4 regulations. Altogether, the present study collects evidence that those oil treatments might generate insulin resistance by targeting GLUT4 expression and translocation specifically in WAT. These alterations are likely to be caused due to the specific local increase in saturated fatty acids that occurred as a consequence of oil daily injections. Copyright © 2010 John Wiley & Sons, Ltd.     

Calorie restriction improves whole-body glucose disposal and insulin resistance in association with the increased adipocyte-specific GLUT4 expression in Otsuka Long-Evans Tokushima fatty rats

Calorie restriction (CR) has been shown to improve peripheral insulin resistance and type 2 diabetes in animal models. However, the exact mechanism of CR on GLUT4 expression and translocation in insulin-sensitive tissues has not been well elucidated. In the present study, we examine the effect of CR on the expression of glucose transporter 4 (GLUT4), GLUT4 translocation, and glucose transport activity in adipose tissue from Otsuka Long-Evans Tokushima Fatty (OLETF) rat and control (LETO) rats. CR (70% of satiated group) ameliorated hyperglycemia and improved impaired glucose tolerance (IGT) in OLETF rats. In skeletal muscle, the expression levels of GLUT4 and GLUT1 were not significantly different between LETO and OLETF rats, and were not affected by CR. By contrast, the expression level of GLUT4 was markedly decreased in the adipose tissue of OLETF rats, but was dramatically increased by CR. The GLUT4 recruitment stimulated by insulin was also improved in OLETF rat adipocytes by CR. The insulin-stimulated 2-deoxyglucose (2DG) uptake was significantly increased in adipocytes from the CR OLETF rats, as compared with the satiated OLETF rats. Taken together, these results suggest that CR improves whole body glucose disposal and insulin resistance in OLETF rats, and that these effects may associate with the increased adipocyte-specific GLUT4 expression.     

Combination therapy with nateglinide and telmisartan ameliorates insulin resistance in zucker Fatty rats by suppressing advanced glycation end product receptor axis

Advanced glycation end products (AGEs) and their receptor (RAGE) have been shown to play a role in insulin resistance. We have previously shown that combination therapy with nateglinide (NAT) and telmisartan (TEL) improves postprandial metabolic derangements in Zucker fatty (ZF) rats, an animal model of insulin resistance with obesity. However, effects of combination therapy on insulin resistance remain unknown. We investigated here whether combination therapy with TEL and NAT could ameliorate insulin resistance in ZF rats by suppressing AGE-RAGE axis. NAT and/or TEL inhibited insulin receptor substrate-1 (IRS-1) serine phosphorylations at 307 and 636/639 residues in the liver of ZF rats. Further, combination therapy with NAT and TEL, but not each monotherapy alone, significantly restored the decrease in hepatic IRS-1 tyrosine phosphorylation in these animals. In addition, serum levels of AGEs, RAGE expression levels in the liver and hepatic AGE-RAGE index were decreased in NAT plus TEL-treated ZF rats. The present study suggests that combination therapy with NAT and TEL could ameliorate insulin resistance in ZF rats by suppressing the AGE-RAGE axis in the liver.     

Differential expression of the melanocortin-4 receptor in male and female C57BL/6J mice

The melanocortin 4 receptor is a member of melanocortin receptors of G-protein-coupled receptors. By binding to melanocortin receptor agonists or antagonists, MC4R participates in the regulating of food intake, weight, energy homeostasis and sexual behavior. By activating the protein kinase A and leptin-melanocortin signalling pathways, MC4R mediates the amplification of signals from the hypothalamo–pituitary–adrenal and hypothalamo–pituitary–thyroid axes. This process permits peripheral information about the status of energy metabolism to be transmitted to the central nervous system. The hypothalamic nuclei then integrate these signals to evoke the appropriate reaction. We found that different sexes exhibited distinct metabolic regulation abilities, likely due to differences in these signalling pathways. MC4R plays a key role in coordinating the afferent messages from the peripheral and regulatory signals by controlling food intake and energy expenditure. To probe the disparities in metabolism and weight regulation between the sexes, we analyzed the expression of MC4R in different tissues from male and female mice by qRT-PCR and immunofluorescence. The results show that the expression of MC4R in brain and kidney is higher in female mice than in male mice, but in the livers, the result is opposition. Additionally, in both sexes, the expression of MC4R is higher in the brain than in the kidneys, and its expression in the liver is lowest, in males, the expression of MC4R in the testis is higher than that in the kidneys. These data show that the expression of MC4R exist different between sexes mice.     

Reversal of obesity and insulin resistance by a non-peptidic glucagon-like peptide-1 receptor agonist in diet-induced obese mice

Background

Glucagon-like peptide-1 (GLP-1) is recognized as an important regulator of glucose homeostasis. Efforts to utilize GLP-1 mimetics in the treatment of diabetes have yielded clinical benefits. A major hurdle for an effective oral therapy has been the difficulty of finding a non-peptidic GLP-1 receptor (GLP-1R) agonist. While its oral bioavailability still poses significant challenges, Boc5, one of the first such compounds, has demonstrated the attainment of GLP-1R agonism in diabetic mice. The present work was to investigate whether subchronic Boc5 treatment can restore glycemic control and induce sustainable weight loss in diet-induced obese (DIO) mice, an animal model of human obesity and insulin resistance.

Methodology/Principal Findings

DIO mice were treated three times a week with Boc5 (0.3, 1 and 3 mg) for 12 weeks. Body weight, body mass index (BMI), food intake, fasting glucose, intraperitoneal glucose tolerance and insulin induced glucose clearance were monitored regularly throughout the treatment. Glucose-stimulated insulin secretion, β-cell mass, islet size, body composition, serum metabolic profiles, lipogenesis, lipolysis, adipose hypertrophy and lipid deposition in the liver and muscle were also measured after 12 weeks of dosing. Boc5 dose-dependently reduced body weight, BMI and food intake in DIO mice. These changes were associated with significant decreases in fat mass, adipocyte hypertrophy and peripheral tissue lipid accumulation. Boc5 treatment also restored glycemic control through marked improvement of insulin sensitivity and normalization of β-cell mass. Administration of Boc5 (3 mg) reduced basal but enhanced insulin-mediated glucose incorporation and noradrenaline-stimulated lipolysis in isolated adipocytes from obese mice. Furthermore, circulating leptin, adiponectin, triglyceride, total cholesterol, nonesterified fatty acid and high-density lipoprotein/low-density lipoprotein ratio were normalized to various extents by Boc5 treatment.

Conclusions/Significance

Boc5 may produce metabolic benefits via multiple synergistic mechanisms and may represent an attractive tool for therapeutic intervention of obesity and diabetes, by means of non-peptidic GLP-1R agonism.     

灵芝多糖对3T3-L1胰岛素抵抗细胞模型PI-3K p85和GLUT4蛋白表达的影响

目的 研究灵芝多糖对3T3-L1胰岛素抵抗细胞模型PI-3K p85和GLUT4蛋白表达的影响,探讨灵芝多糖改善胰岛素抵抗的分子机制.方法 3T3-L1前脂肪细胞经1-甲基-3-异丁基-黄嘌呤、地塞米松、胰岛素诱导分化成3T3-L1脂肪细胞,以葡萄糖氧化酶法测定培养液中残余的葡萄糖含量.比较二甲双胍组,检测培养液中葡萄糖含量及PI-3K p85和GLUT4蛋白表达变化.结果 地塞米松联合胰岛素诱导3T3-L1脂肪细胞产生胰岛素抵抗,细胞对葡萄糖的摄取量减少.灵芝多糖可改善3T3-L1脂肪细胞胰岛素抵抗.胰岛素抵抗细胞的PI-3K p85和GLUT4蛋白表达明显减少;应用灵芝多糖后,相关蛋白表达增加.结论 灵芝多糖通过提高PI-3K p85和GLUT4蛋白的表达,参与胰岛素抵抗状态下3T3-L1细胞的葡萄糖代谢.     

Disturbances of systemic and hippocampal insulin sensitivity in macrophage migration inhibitory factor (MIF) knockout male mice lead to behavioral changes associated with decreased PSA-NCAM levels

Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine well known for its role in inflammation enhancement. However, a growing body of evidence is emerging on its role in energy metabolism in insulin sensitive tissues such as hippocampus, a brain region implicated in cognition, learning and memory. We hypothesized that genetic deletion of MIF may result in the specific behavioral changes, which may be linked tо impairments in brain or systemic insulin sensitivity by possible changes of the hippocampal synaptic plasticity. To assess memory, exploratory behavior and anxiety, three behavioral tests were applied on Mif gene-deficient (MIF^−/−) and “wild type” C57BL/6J mice (WT). The parameters of systemic and hippocampal insulin sensitivity were also determined. The impact of MIF deficiency on hippocampal plasticity was evaluated by analyzing the level of synaptosomal polysialylated-neural cell adhesion molecule (PSA-NCAM) plasticity marker and mRNA levels of different neurotrophic factors.The results showed that MIF^−/− mice exhibit emphasized anxiety-like behaviors, as well as impaired recognition memory, which may be hippocampus-dependent. This behavioral phenotype was associated with impaired systemic insulin sensitivity and attenuated hippocampal insulin sensitivity, characterized by increased inhibitory Ser³⁰⁷ phosphorylation of insulin receptor substrate 1 (IRS1). Finally, MIF^−/− mice displayed a decreased hippocampal PSA-NCAM level and unchanged Bdnf, NT-3, NT-4 and Igf-1 mRNA levels.The results suggest that the lack of MIF leads to disturbances of systemic and hippocampal insulin sensitivity, which are possibly responsible for memory deficits and anxiety, most likely through decreased PSA-NCAM-mediated neuroplasticity rather than through neurotrophic factors.     

Oxymatrine ameliorates insulin resistance in rats with type 2 diabetes by regulating the expression of KSRP,PETN, and AKT in the liver

Insulin resistance plays a key role in the development and progression of type 2 diabetes mellitus (T2DM). Recent studies found that insulin resistance was associated with the dysfunction of KH-type splicing regulatory protein (KSRP) expression and AKT pathway, and that oxymatrine possesses an antidiabetic effect. The aim of the present study was to investigate whether the protection of oxymatrine against T2DM was associated with the modulation of the KSRP expression and AKT pathway. Sprague-Dawley rats were fed a high-fat diet and injected with streptozotocin intraperitoneally to induce T2DM, which led to an increase in blood glucose levels and insulin resistance, and a decrease in insulin sensitivity and glycogen synthesis concomitant with KSRP downregulation, PTEN upregulation, and AKT phosphorylation deficiency. The administration of oxymatrine decreased blood glucose levels and insulin resistance, increased insulin sensitivity, and improved glycogen synthesis in the liver of T2DM rats, through a reversal in the expression of KSRP, PTEN, and AKT. On the basis of these observations, we concluded that oxymatrine can protect T2DM rats from insulin resistance through the regulation of the KSRP, PETN, and AKT expression in the liver.     

Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters

Stress is an important physiological regulator of brain function in young and adult mammals. The mechanisms underlying regulation of the consequences of stress, and in particular severe chronic stress, are thus important to investigate. These consequences most likely involve changes in synaptic function of brain areas being part of neural networks that regulate responses to stress. Cell adhesion molecules have been shown to regulate synaptic function in the adult and we were thus interested to investigate a regulatory mechanism that could influence expression of three adhesion molecules of the immunoglobulin superfamily (NCAM, L1 and CHL1) after exposure of early postnatal and adult mice to repeated stress. We hypothesized that reduction of adhesion molecule expression after chronic stress, as observed previously in vivo, could be due to gene silencing of the three molecules by DNA methylation. Although adhesion molecule expression was reduced after exposure of C57BL/6 mice to stress, thus validating our stress paradigm as imposing changes in adhesion molecule expression, we did not observe differences in methylation of CpG islands in the promoter regions of NCAM, L1 and CHL1, nor in the promoter region of the glucocorticoid receptor in the hippocampus, the expression of which at the protein level was also reduced after stress. We must therefore infer that severe stress in mice of the C57BL/6 strain downregulates adhesion molecule levels by mechanisms that do not relate to DNA methylation.Key words: stress, immunoglobulin superfamily, adhesion molecules, promoter, DNA methylation, hippocampus, glucocorticoid receptor     

Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters

Stress is an important physiological regulator of brain function in young and adult mammals. The mechanisms underlying regulation of the consequences of stress, and in particular severe chronic stress, are thus important to investigate. These consequences most likely involve changes in synaptic function of brain areas being part of neural networks that regulate responses to stress. Cell adhesion molecules have been shown to regulate synaptic function in the adult and we were thus interested to investigate a regulatory mechanism that could influence expression of three adhesion molecules of the immunoglobulin superfamily (NCAM, L1 and CHL1) after exposure of early postnatal and adult mice to repeated stress. We hypothesized that reduction of adhesion molecule expression after chronic stress, as observed previously in vivo, could be due to gene silencing of the three molecules by DNA methylation. Although adhesion molecule expression was reduced after exposure of C57BL/6 mice to stress, thus validating our stress paradigm as imposing changes in adhesion molecule expression, we did not observe differences in methylation of CpG islands in the promoter regions of NCAM, L1 and CHL1, nor in the promoter region of the glucocorticoid receptor in the hippocampus, the expression of which at the protein level was also reduced after stress. We must therefore infer that severe stress in mice of the C57BL/6 strain downregulates adhesion molecule levels by mechanisms that do not relate to DNA methylation.     

The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK, and pAKT in obese mice

We examined mechanisms by which L-4F reduces obesity and diabetes in obese (ob) diabetic mice. We hypothesized that L-4F reduces adiposity via increased pAMPK, pAKT, HO-1, and increased insulin receptor phosphorylation in ob mice. Obese and lean mice were divided into five groups: lean, lean-L-4F-treated, ob, ob-L-4F-treated, and ob-L-4F-{"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. Food intake, insulin, glucose adipocyte stem cells, pAMPK, pAKT, CB1, and insulin receptor phosphorylation were determined. Subcutaneous (SAT) and visceral adipose tissue (VAT) were determined by MRI and hepatic lipid content by magnetic resonance spectroscopy. SAT and VAT volumes decreased in ob-L-4F-treated animals compared with control. L-4F treatment decreased hepatic lipid content and increased the numbers of small adipocytes (P < 0.05) and phosphorylation of insulin receptors. L-4F decreased CB1 in SAT and VAT and increased pAKT and pAMPK in endothelium. L-4F-mediated improvement in endothelium was prevented by {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002. Inhibition of pAKT and pAMPK by {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 was associated with an increase in glucose levels. Upregulation of HO-1 by L-4F produced adipose remodeling and increased the number of small differentiated adipocytes. The anti-obesity effects of L-4F are manifested by a decrease in visceral fat content with reciprocal increases in adiponectin, pAMPK, pAKT, and phosphorylation of insulin receptors with improved insulin sensitivity.