cl-316243 and Insulin-Resistance

Brown adipose tissue (BAT) is emerging as a target to beat obesity through the dissipation of chemical energy to heat. However, the molecular mechanisms of brown adipocyte thermogenesis remain to be further elucidated. Here, we show that KCTD10, a member of the polymerase delta-interacting protein 1 family, was reduced in BAT by cold stress and a β3 adrenoceptor agonist. Moreover, KCTD10 level increased in the BAT of obese mice, and KCTD10 overexpression attenuates uncoupling protein 1 expression in primary brown adipocytes. BAT-specific KCTD10 knockdown mice had increased thermogenesis and cold tolerance protecting from high-fat diet (HFD)-induced obesity. Conversely, overexpression of KCTD10 in BAT caused reduced thermogenesis, cold intolerance, and obesity. Mechanistically, inhibiting Notch signaling restored the KCTD10 overexpression-suppressed thermogenesis. Our study presents that KCTD10 serves as an upstream regulator of Notch signaling pathway to regulate BAT thermogenesis and whole-body metabolic function.

Topics: Adipose Tissue, Brown; Animals; Cell Cycle Proteins; Cold-Shock Response; Dioxoles; Female; Gene Knockdown Techniques; Insulin Resistance; Male; Mice, Inbred C57BL; Obesity; Potassium Channels, Voltage-Gated; Receptors, Notch; Signal Transduction; Thermogenesis; Transcription Factor HES-1; Uncoupling Protein 1

Exposure of mice or humans to cold promotes significant changes in brown adipose tissue (BAT) with respect to histology, lipid content, gene expression, and mitochondrial mass and function. Herein we report that the lipid droplet coat protein Perilipin 5 (PLIN5) increases markedly in BAT during exposure of mice to cold. To understand the functional significance of cold-induced PLIN5, we created and characterized gain- and loss-of-function mouse models. Enforcing PLIN5 expression in mouse BAT mimics the effects of cold with respect to mitochondrial cristae packing and uncoupled substrate-driven respiration. PLIN5 is necessary for the maintenance of mitochondrial cristae structure and respiratory function during cold stress. We further show that promoting PLIN5 function in BAT is associated with healthy remodeling of subcutaneous white adipose tissue and improvements in systemic glucose tolerance and diet-induced hepatic steatosis. These observations will inform future strategies that seek to exploit thermogenic adipose tissue as a therapeutic target for type 2 diabetes, obesity, and nonalcoholic fatty liver disease.

Topics: Adipose Tissue, Brown; Adipose Tissue, White; Adrenergic beta-3 Receptor Agonists; Animals; Cold Temperature; Diet, High-Fat; Dioxoles; Glucose; Humans; Insulin Resistance; Lipase; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mitochondria; Models, Biological; Non-alcoholic Fatty Liver Disease; Perilipin-5; Sirtuin 1; Thermogenesis; Uncoupling Protein 1; Up-Regulation

Brown adipose tissue (BAT), characterized by the presence of uncoupling protein 1 (UCP1), has been described as metabolically active in humans. Lou/C rats, originating from the Wistar strain, are resistant to obesity. We previously demonstrated that Lou/C animals express UCP1 in beige adipocytes in inguinal white adipose tissue (iWAT), suggesting a role of this protein in processes such as the control of body weight and the observed improved insulin sensitivity. A β3 adrenergic agonist was administered for 2 weeks in Wistar and Lou/C rats to activate UCP1 and delineate its metabolic impact. The treatment brought about decreases in fat mass and improvements in insulin sensitivity in both groups. In BAT, UCP1 expression increased similarly in response to the treatment in the two groups. However, the intervention induced the appearance of beige cells in iWAT, associated with a marked increase in UCP1 expression, in Lou/C rats only. This increase was correlated with a markedly enhanced glucose uptake measured during euglycemic-hyperinsulinemic clamps, suggesting a role of beige cells in this process. Activation of UCP1 in ectopic tissues, such as beige cells in iWAT, may be an interesting therapeutic approach to prevent body weight gain, decrease fat mass, and improve insulin sensitivity.

Topics: Adipose Tissue, Brown; Adipose Tissue, White; Adrenergic beta-3 Receptor Agonists; Animals; Body Composition; Dioxoles; Insulin Resistance; Ion Channels; Male; Mitochondrial Proteins; Obesity; Rats; Rats, Wistar; Thermogenesis; Uncoupling Protein 1

Homeotherms have specific mechanisms to maintain a constant core body temperature despite changes in thermal environment, food supply, and metabolic demand. Brown adipose tissue, the principal thermogenic organ, quickly and efficiently increases heat production by dissipating the mitochondrial proton motive force. It has been suggested that activation of brown fat, via either environmental (i.e. cold exposure) or pharmacologic means, could be used to increase metabolic rate and thus reduce body weight. Here we assess the effects of intermittent cold exposure (4°C for one to eight hours three times a week) on C57BL/6J mice fed a high fat diet. Cold exposure increased metabolic rate approximately two-fold during the challenge and activated brown fat. In response, food intake increased to compensate fully for the increased energy expenditure; thus, the mice showed no reduction in body weight or adiposity. Despite the unchanged adiposity, the cold-treated mice showed transient improvements in glucose homeostasis. Administration of the cannabinoid receptor-1 inverse agonist AM251 caused weight loss and improvements in glucose homeostasis, but showed no further improvements when combined with cold exposure. These data suggest that intermittent cold exposure causes transient, meaningful improvements in glucose homeostasis, but without synergy when combined with AM251. Since energy expenditure is significantly increased during cold exposure, a drug that dissociates food intake from metabolic demand during cold exposure may achieve weight loss and further metabolic improvements.

Topics: Adipose Tissue, Brown; Animals; Biomarkers; Body Composition; Body Weight; Cold Temperature; Deoxyglucose; Dioxoles; Energy Metabolism; Feeding Behavior; Glucose; Homeostasis; Hormones; Insulin Resistance; Male; Mice; Mice, Inbred C57BL; Obesity; Piperidines; Pyrazoles

One of the common complications of type 2 diabetes mellitus (DM2) are cardiovascular diseases and dysfunctions of the reproductive system, indicating the urgency of developing new approaches to their correction. Last years for the treatment of DM2 began to use bromocryptine (BC), the agonist of type 2 dopamine receptors, which not only restores the energy metabolism, but also prevents the development of cardiovascular diseases. However, the mechanisms and targets of BC action are poorly understood. The purpose of this study was to investigate the effect of BC treatment on functional activity of adenylyl cyclase signaling system (ACSS) in the myocardium and testes of male rats with DM2, which is caused by high-fat diet and treatment with streptozotocin (25 mg/kg). The treatment with BC (60 days, orally at a dose of 0.6 mg/kg once every two days) was started 90 days after the beginning of high-fat diet. Diabetic rats had an increased body weight, elevated triglycerides level, impaired glucose tolerance, and insulin resistance. The treatment with BC resulted in the restoration of glycometabolic indicators and in the improvement of insulin sensitivity. Adenylyl cyclase (AC) stimulating effects of guanylylimidodiphosphate (GppNHp), relaxin, and agonists of β-adrenergic receptors (β3-AR)--isoproterenol and norepinephrine were decreased in the miocardium of the diabetic rats. The corresponding effects of the β-agonists BRL-37344 and CL-316243 was preserved. The inhibitory effect of somatostatin on forskolin-stimulated AC activity was attenuated, while the inhibitory effect of noradrenaline mediated through α2-AR increased. The treatment with BC resulted in the normalization of the adrenergic signaling in the myocardium and partially restoration of AC effects of relaxin and somatostatin. In the testes of diabetic rats, the basal and stimulated by GppNHp, forskolin, human chorionic gonadotropin and pituitary AC-activating polypeptide AC activity were decreased, and the inhibitory effect of somatostatin was attenuated. The changes in testicular ACSS in the case of BC treatment were weakly expressed. Thus, long-term BC treatment restores the functional activity of ACSS in the myocardium and testes of diabetic rats that underlies the therapeutic effect of BC on functions of the cardiovascular and reproductive systems disturbed in DM2 and should be considered when developing strategies for treatment type 2 diabetes and its complications.

Topics: Adenylyl Cyclases; Administration, Oral; Animals; Blood Glucose; Bromocriptine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diet, High-Fat; Dioxoles; Dopamine Agonists; Drug Administration Schedule; Ethanolamines; Guanylyl Imidodiphosphate; Humans; Insulin Resistance; Isoproterenol; Male; Myocardium; Norepinephrine; Rats; Rats, Wistar; Relaxin; Signal Transduction; Streptozocin; Testis; Triglycerides

Obesity is a risk factor for the development of insulin resistance and is one of the most important contributors to the pathogenesis of type 2 diabetes, which acts mainly through the secretion of adipokines such as TNF-α that may influence insulin sensitivity. TNF-α affects many aspects of adipocyte function, such as adipocyte development and lipid metabolism.. We demonstrated that there is a correlation between the expressions of TNF-α in retroperitoneal WAT and insulin-resistance in 8 genetically obese fa/fa rats. Treatment of animals with CL 316,243, a β3-adrenergic agonist, showed an improvement of insulin-resistance that was linked with the suppression of TNF-α mRNA expression in WAT.. These results confirm the association between TNF-α expression and the insulin-resistant condition in rats. Our finding indicates that the hyperglycaemia and hyperinsulinemia induced by insulin-resistance correlated positively with the expression of TNF-α mRNA in an abdominal WAT depot.. We conclude that CL 316,243 possesses both anti-diabetic effects and anti-obesity effects in rodents.

Topics: Abdominal Fat; Adipose Tissue, White; Adrenergic beta-Agonists; Animals; Blood Glucose; Blotting, Northern; Body Weight; Dioxoles; Down-Regulation; Fatty Acids; Gene Expression; Hypoglycemic Agents; Insulin; Insulin Resistance; Male; Obesity; Rats; Rats, Zucker; Receptors, Adrenergic, beta-3; Tumor Necrosis Factor-alpha

We investigated the effects of beta(3)-adrenoceptor agonist, 5-[(2R)-2-[[(2R)-2-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]-1,3-benzodioxole-2,2-dicarboxylate (CL-316,243) in obese diabetic KKAy mice. Two weeks' subcutaneous administration of CL-316,243 reduced serum levels of glucose, insulin, triglyceride, free fatty acid and tumor necrosis factor-alpha (TNF-alpha), and increased adiponectin. Adiponectin, adiponectin receptors and beta(3)-adrenoceptor mRNA expressions were reduced in epididymal white adipose tissue in KKAy mice, and CL-316,243 recovered these mRNA expressions. Meanwhile, CL-316,243 suppressed the overexpressed mRNA level of TNF-alpha in both epididymal white adipose tissue and brown adipose tissue. These data suggest that the normalization of adiponectin, adiponectin receptors and TNF-alpha may result in the amelioration of obesity-induced insulin resistance.

Topics: Adiponectin; Adipose Tissue; Adrenergic beta-3 Receptor Agonists; Adrenergic beta-Agonists; Animals; Blood Glucose; Body Weight; Diabetes Mellitus; Dietary Fats; Dioxoles; Disease Models, Animal; Eating; Hypoglycemic Agents; Injections, Subcutaneous; Insulin; Insulin Resistance; Lipids; Male; Mice; Obesity; Receptors, Adiponectin; Receptors, Adrenergic, beta-3; Tumor Necrosis Factor-alpha

Oleoyl-estrone (OE) decreases appetite, induces adipose tissue wasting and resets the ponderostat setting, sparing glucose and protein. The beta3-adrenergic agonists increase energy expenditure and lipolysis. We studied the combination of both treatments to enhance fat mobilization. Overweight male rats received oral OE for 10 days; they were compared with controls and rats receiving a beta3-adrenergic agonist, CL316,243 (B3A); another group received both OE and B3A. Serum 3-hydroxybutyrate, NEFA, triacylglycerols and glucose showed only slight changes in all groups vs. controls; OE-treated rats showed lower cholesterol. OE decreased food intake and B3A increased energy expenditure. OE rats lost about 15%, B3A 24%, and those receiving both compounds lost 39% of their initial total body energy. In all cases, most of this energy imbalance was accounted for by the loss of body lipid. The combined treatment of OE and B3A reduced food intake, nevertheless maintaining a high energy expenditure. The combination of a beta3-adrenergic agonist with OE may help compensate the short-lived effects of the agonist and enhance the lipid mobilization action of OE. The eventual combination of both compounds should be explored as a way to obtain faster and more effective ways to treat obesity.

Topics: 3-Hydroxybutyric Acid; Adrenergic beta-Agonists; Analysis of Variance; Animals; Blood Glucose; Dioxoles; Eating; Energy Metabolism; Estrone; Fatty Acids, Nonesterified; Insulin Resistance; Lipid Mobilization; Male; Obesity; Oleic Acids; Rats; Rats, Wistar; Triglycerides

Our aim was to determine the effect of a beta3-adrenoceptor agonist on plasma adiponectin levels and on the level of expression of mRNA for adiponectin, adiponectin receptor 1, and adiponectin receptor 2 in db/db mice. Two weeks' oral administration of CL-316,243 led to decreased plasma levels of hemoglobin A1c, glucose, insulin, triglyceride and free fatty acid, and to an increased plasma adiponectin levels. It also improved insulin resistance in the oral glucose tolerance test. Adiponectin mRNA expression was significantly higher in the CL-316,243-treatment group than in the control group in epididymal white adipose tissue but not in brown adipose tissue, soleus muscle or liver. Adiponectin receptor 2 mRNA expression was significantly lower only in the liver of the CL-316,243-treatment group (versus the control group). These results suggest that the increased plasma adiponectin levels seen in db/db mice treated with this beta3-adrenoceptor agonist induce a down-regulation of adiponectin receptor 2 mRNA expression specifically in the liver.

Topics: Adiponectin; Adipose Tissue; Adrenergic beta-3 Receptor Agonists; Adrenergic beta-Agonists; Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Dioxoles; Eating; Fatty Acids; Gene Expression; Glucose Tolerance Test; Glycated Hemoglobin; Insulin; Insulin Resistance; Intercellular Signaling Peptides and Proteins; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Obesity; Receptors, Adiponectin; Receptors, Cell Surface; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors

Insulin resistance and obesity are central components of the metabolic syndrome which has become the leading cause of cardiovascular morbidity and mortality worldwide. Direct interactions of the beta (3)-adrenoceptor system with adipocyte signaling and function in humans remain poorly understood. However, this might have important consequences for the regulation of energy homeostasis and insulin resistance in states of hyperinsulinemia and sympatho-adrenergic overactivity. We therefore investigated beta (3)-adrenoceptor-mediated effects on insulin signaling and glucose uptake in mammary adipocytes of healthy women that underwent breast reduction surgery. Glucose uptake was strongly induced by insulin stimulation. This was paralleled by robust induction of insulin receptor kinase activity, insulin receptor substrate-1-associated phosphatidylinositol-3 kinase activity, and protein kinase B phosphorylation. Treatment with the beta (3)-adrenoceptor-selective agonist CL316,243 alone, neither induced alterations in the early insulin signaling cascade nor changed the basal level of glucose uptake. By contrast, pretreatment with the beta (3)-adrenoceptor agonist inhibited the insulin-induced insulin receptor substrate-1-associated phosphatidylinositol-3 kinase activity by 50 % and protein kinase B phosphorylation by 40 % without affecting insulin receptor kinase activity upstream. However, on the functional level insulin-induced glucose uptake remained unchanged by beta (3)-adrenoceptor stimulation. Our data demonstrate an insulin receptor-independent negative influence of beta (3)-adrenoceptor stimulation on proximal insulin signaling. This inhibition is apparently dissociated from glucose uptake in human adipocytes.

Topics: Acrylates; Adipocytes; Adrenergic beta-3 Receptor Agonists; Adrenergic beta-Agonists; Biological Transport, Active; Cells, Cultured; Dioxoles; Female; Glucose; Humans; Insulin; Insulin Resistance; Obesity; Receptors, Adrenergic, beta-3; Signal Transduction

Between 7 and 14 weeks of age, male Sprague-Dawley rats develop a greater than 50% loss in insulin-stimulated glucose transport in skeletal muscle. We treated rats aged 14 weeks with the beta-3 adrenergic agonist CL316,243 (1 mg/kg/day by minipump for 14 days). Treatment resulted in a 56% reduction in visceral fat (P < 0.05). Muscle mass and body weight were unchanged. In strips of soleus muscle isolated from rats treated with CL316,243, basal transport of [(3)H]-2-deoxyglucose (2-DOG) was unchanged (105.8 +/- 7.5 nmol/g/min for vehicle vs 122.0 +/- 8.7 for CL316,243). However, in rats treated with CL316,243, the increase in 2-DOG transport in response to a maximal concentration of insulin was substantially increased (55.5 +/- 13.1 nmol/g/min for vehicle vs 102.4 +/- 13.5 for CL316,243, P < 0.03). CL 316,243 caused no significant changes in fasting glucose, insulin, or free fatty acids. Treatment of soleus muscle strips in vitro with CL316,243 (either 0.1 nM or 1.0 nM for 120 min at 37 degrees C) had no effect either on basal 2-DOG transport or on insulin-stimulated transport. We conclude that the CL316,243 causes a reduction in visceral fat and a reversal of muscle insulin resistance. The effect CL 316,243 on muscle insulin responses appears to be indirect, as it did not occur in vitro.

Topics: Adrenergic beta-3 Receptor Agonists; Adrenergic beta-Agonists; Animals; Biological Transport, Active; Blood Glucose; Body Composition; Deoxyglucose; Dioxoles; Fatty Acids, Nonesterified; In Vitro Techniques; Insulin; Insulin Resistance; Male; Muscle, Skeletal; Rats; Rats, Sprague-Dawley

Stimulation of beta3-adrenergic receptors increases metabolic rate via lipolysis in white adipose tissue (WAT) and thermogenesis in brown adipose tissue (BAT). Other acute effects include decreased gastrointestinal motility and food intake and increased insulin secretion. Chronic treatment with a beta3 agonist ameliorates diabetes and obesity in rodents. We studied the effects of beta3 stimulation in A-ZIP/F-1 mice, which have virtually no WAT, a reduced amount of BAT, severe insulin resistance, and diabetes. In contrast with wild-type mice, treatment of A-ZIP/F-1 mice with CL316243, a beta3-adrenergic agonist, did not increase O2 consumption. A single dose of CL316243 produced a 2-fold increase in serum free fatty acids, a 53-fold increase in insulin, and a 2.4-fold decrease in glucose levels in wild-type mice but no change in A-ZIP/F-1 animals. The A-ZIP/F-1 mice also did not show reduced gastrointestinal motility or 24-h food intake during beta3 stimulation. Chronic administration of CL316243 to the A-ZIP/F-1 mice did not improve their thermogenesis, hyperglycemia, or hyperinsulinemia. Thus, all of the beta3 effects studied were absent in the lipoatrophic A-ZIP/F-1 mice, including the effects on nonadipose tissues. From these results, we suggest that all of the effects of beta3 agonists are initiated at the adipocyte with the nonadipose effects being secondary events presumably mediated by signals from adipose tissue.

Topics: Adipose Tissue; Adipose Tissue, Brown; Adrenergic beta-Agonists; Animals; Atrophy; Blood Glucose; Carrier Proteins; Diabetes Mellitus; Dioxoles; Eating; Fatty Acids, Nonesterified; Female; Gastrointestinal Motility; Insulin; Insulin Resistance; Ion Channels; Membrane Proteins; Mice; Mice, Transgenic; Mitochondrial Proteins; Oxygen Consumption; Receptors, Adrenergic, beta-3; RNA, Messenger; Thermogenesis; Uncoupling Protein 1