The Effect Of Melatonin And Its Receptor Agonist On Insulin Resistance In 3t3-l1 Adipocytes

Objectives:To explore the effects of Melatnoin and its receptor agonist(Neu-P11) on glucose uptake and expression of triglyceride, Leptin , Adiponectin and Adiponectin receptor of correlation factor of insulin resistance, AMPK(amp-activated Protein kinase) and its phosphorylation of AMPK ,ACC and its phosphorylation of ACC in 3T3-L1 adipocytes treated with or without free fatty acids.Methods: The experiments were designed as follows:first, 3T3-L1 preadipocytes, were maintained in DMEM culture medium supplemented with 10%fetal calf serum for adipogenesis,3T3-L1 preadipocytes were grown into confluence in a six-well plate,and then incubated in adipogenic cocktail(5μg/ml insulin,0.5mM isobutylmethylxanthine, and 1μM dexamethasone)for 2 days.This was followed by incubation in insulin-supplemented medium for additional 4 days.After 10～12days,cells were differentiated into adipocytes as determined by Oil Red O staining.Then, Using of FFA induced insulin resistance in adipocytes, and cell glucose uptake was measured by glucose oxidase method. Detection of Mel NEU-P11 and its receptor agonist treatment on FFA 3T3-L1 adipocyte glucose uptake and its related protein expression. Leptin, Adiponectin, Adiponectin receptor, AMPK, and phosphorylation of AMPK,ACC and phosphorylation of ACC protein expressions were detected by Western blot, TG of expression were detected by triglyceride kit.Results: 3T3-L1 cells were differentiated into adipocytes as determined by Oil Red O staining.3T3-L1 adipocytes were treated with palmic acid to induce insulin resistance.Insulin-induced glucose uptake was measured to determine insulin sensitivity.The result showed that insulin-induced glucose uptake was inhibited after a 6 h-treatment with palmic acid and intracellular triglyceride content increased, adiponectin and adiponectin receptor1, Leptin, AMPK, and phosphorylation of AMPK, ACC and phosphorylation of ACC expression decreased, Mel/Neu-P11 to handle join together before the end of 6 hours incubation, The result showed that the ability of glucose uptake increased with insulin concentrations increased significantly, triglyceride content of the intervention decreased to near normal levels treatment with Mel/Neu-P11, and we also found that:the expression level of adiponectin and adiponectin receptor 1, AMPK, and phosphorylation of AMPK, ACC and phosphorylation of ACC of intervention show upward trend treatment with Mel/Neu-P11, close to the normal, level of leptin did not change significantly with Mel/Neu-P11 intervention for 6 hours,there is no statistical significance.Conclusion: 1.Mel/Neu-P11 can increase insulin-stimulated glucose uptake in the adipocytes with treatment by palmitic acid;2.Mel/Neu-P11 can increase expression of adiponectin and adiponectin receptor 1 in the adipocytes with treatment by palmitic acid, further activation of AMPK, leading to loss of activity downstream protein phosphorylation of ACC,so as to promote the oxidation of intracellular fatty acid metabolism, reduce triglyceride content in adipocytes, thus improving insulin resistance.