Adiponectin Activates AMP-activated Protein Kinase Via LKB1 Pathway In Skeletal Muscels

Objective To investigate the expression of adiponectin and AMP-activated protein kinase (AMPK) in normal-fed rats'and high-fat-fed rats'muscles. To explore whether adiponectin and AMPK play roles on the metabolism of lipid, the metabolism of glucose and Insulin Resistance. To discuss in skeletal muscles if adiponectin activates AMPK via LKB1 pathway or not.Methods 30 male Sprague-Dawley rats(SD rats) were randomly divided into two groups: 15 were fed with normal control diet as NC group; the rest 15 were fed with a high-fat diet as HF group. After 16 weeks, the average BW of HF group were over 20% higher than NC group. All the rats were weighed under anesthesia. The free fatty acid(FFA), triglyceride(TG), total cholesterol(TCH), fasting plasma glucose(FPG), fasting insulin(FINS) and adiponectin in the serum were measured. After all the rats were killed, the protein levels of AMPKα, P-AMPKαand P-LKB1 in the skeletal muscles were analyzed with Western blot. SD rat's skeletal muscle cells were primarily cultured in vitro. Then these cells were randomly divided into three groups: CON group, ADI group and RAD+ADI group. ADI group was incubated with adiponectin. RAD+ADI group was incubated with radicicol and adiponectin. The expression of AMPKα, P-AMPKαand P-LKB1 in cells were analyzed with immunofluorescence technique.Results Compared with NC group, the BW, FFA, TG, FPG and FINS in HF group were significantly higher (P〈0.05), however, the serum adiponectin levels were lower(P〈0.05). The expression of P-AMPKαand P-LKB1 in the muscles of HF group were lower than that in NC group. In primary skeletal muscle cells, the expression of P-AMPKαand P-LKB1 in ADI group were higher than in CON group(P〈0.05), however, those in RAD+ADI group were lower than in CON group(P〈0.05). Moreover, compared with ADI group, the expression of P-AMPKαand P-LKB1 in RAD+ADI group were lower(P〈0.05).Conclusions High-fat nutrition diet reduced the adiponectin level and the activity of AMPK, promoted the synthesis of TG, increased the blood glucose, induced obesity and Insulin Resistance in rats. LKB1 is an important upstream activator of AMPK in skeletal muscles. Adiponectin may up-regulate the expression of P-AMPKαand P-LKB1. In addition, adiponectin may activate AMPK via LKB1 pathway in skeletal muscles of SD rats.