[Effects of globular adiponectin, glucose and free fatty acid on AMPK and ACC phosphorylation in INS-1 beta cells].

OBJECTIVE: To investigate effects of glucose and free fatty acid at different concentrations on phosphorylation of adenosine-5'-monophosphate activated protein kinase(AMPK) and acetyl CoA carboxylase (ACC) in INS-1 cells, and effects of globular adiponectin on phosphorylation of AMPK and ACC. METHODS: INS-1 cells were cultured and treated with 5 mmol/L glucose or 0.25 mmol/L free fatty acids, and time courses and dose responses of different dosages of glucose and fatty acid on phosphorylation of AMPK and ACC were measured. We measured the effects of the pharmacological AMPK activator AICAR (5-aminoimidazole-4-carboxamide-riboside) and globular adiponectin on phosphorylation of AMPK and ACC. RESULTS: Glucose and fatty acid at different concentrations inhibited the phosphorylation of AMPK and ACC at the end of 60 min, but AICAR increased the phosphorylation of AMPK and ACC significantly, while 2.5 mg/L globular adiponectin increased the phosphorylation of AMPK and ACC by 23% (P<0.05) and 50% (P<0.05) respectively, at baseline. In the presence of 5 mmol/L glucose, globular adiponectin increased AMPK and ACC phosphorylation by 1.4-fold (P<0.05) and 3-fold (P<0.01), respectively. In the presence of 0.25 mmol/L free fatty acid, globular adiponectin increased AMPK and ACC phosphorylation 3-fold (P<0.05) and 5-fold (P<0.01) respectively. CONCLUSION: In cultured islet cells, glucose and free fatty acid at various concentrations inhibit the phosphorylation of AMPK and ACC, but AICAR and globular adiponectin 2.5 mg/L increase the phosphorylation level. This may constitute a mechanism to increase fatty acid oxidation and decrease triglyceride accumulation in islet beta-cells.