Amelioration of insulin resistance in rat cells by Astragalus polysaccharides and associated mechanisms

The aim of this study was to investigate the function of Astragalus polysaccharides (APS) in ameliorating insulin resistance (IR) in rat cells and to elucidate the associated mechanisms. Fully differentiated, induced 3T3-L1 rat adipocytes were divided into a control group and three intervention groups. The intervention groups were incubated in media containing 0.001, 0.1 and 10 μg/μl APS, respectively, for 48 h. Following treatment, levels of interleukin (IL)-6 and adiponectin secreted by the cultured adipocytes were measured using enzyme-linked immunosorbent assay. Levels of adiponectin secreted by the 3T3-L1 adipocytes in the moderate-concentration intervention group were significantly increased compared with those in the control group (P<0.05), whereas levels of adiponectin secreted by the 3T3-L1 adipocytes in the low- and high-concentration intervention groups were decreased compared with those in the control group (P<0.05 and P>0.05, respectively). Levels of IL-6 secreted by the 3T3-L1 adipocytes in the three intervention groups were lower than those in the control group (P>0.05, P<0.05 and P<0.05 for the low- moderate- and high-concentration intervention groups, respectively), and demonstrated APS dose-dependence. The results indicate that APS are capable of increasing adiponectin secretion and reducing IL-6 secretion by 3T3-L1 rat adipocytes in a dose-dependent manner. These findings may identify a potential mechanism for ameliorating IR using APS.