ABSTRACT
OBJECTIVE：To study the i mprovement effects of α-lipoic acid on glucose metabolism disorder of insulin resistant HepG2 cells. METHODS ：The effects of 25-1 000 µmol/L α-lipoic acid on survival rate of human hepatoma cell HepG2 were determined by MTT assay so as to determine the concentration of α-lipoic acid. Negative control group ，insulin resistance group （1× 10－7 mol/L insulin ），combination resistance group （30 µmol/L sodium arsenite+ 1×10－8 mol/L insulin ），α-lipoic acid low- concentration，medium-concentration and high-concentration groups were set up. HepG 2 cells were treated with α-lipoic acid for 12 h and then cultured with corresponding concentration of sodium arsenite or/and insulin for 24 h. The glucose oxidase method was used to detect the glucose consumption ，colorimetric method was used to detect hexokinase activity and pyruvate kinase activity ， and anthrone method was used to detect glycogen content. Western blot assay was used to detect the protein expression of GLUT 4， p-GSK3β and GSK3β as well as the ratio of p-Akt/Akt and p-GSK3β/GSK3β. RESULTS：25，50，100 µmol/L α-lipoic acid had no significant effect on the survival rates of HepG 2 cells（P＞0.05），and survival rates of H epG2 cells were higher than 96％，so they were used as the low ，medium and high concentration for follow-up study. Compared with negative control group ，glucose consumption，the activities of hexokinase and pyruvate kinase ，glycogen content ，protein expression of GLUT 4 and p-GSK 3β，the ratio of p-Akt/Akt and p-GSK 3β/GSK3β were decreased significantly in insulin resistance group and combined resistance group， while the protein expression of GSK 3β was increased significantly（P＜0.05）. Compared with combination resistance group ，the glucose consumption （except for α-lipoic acid low- concentration group ），the activities of h exokinase（except for α-lipoic acid low-concentration and medium-concentration groups ） andpyruvate kinase （except for α-lipoic acid low-concentration com and medium-concentration groups ）， glycogen contents ， protein expression of GLUT 4 （except for α-lipoic acid mail：bliang163@163.com low-concentration group ）and p-GSK3β，the ratio of p-Akt/ Akt（except for α-lipoic acid low-concentration and medium-concentration groups ）and p-GSK 3β/GSK3β（except for α-lipoic acid low-concentration groups ）were increased significantly in α-lipoic acid groups ，while protein expression of GSK 3β（except for α-lipoic acid low-concentration and medium-concentration groups ） was decreased significantly （P＜0.05）；glycogen content ， protein expression of GLUT 4 and the ratio of p-GSK 3β/GSK3β in α-lipoic acid high-concentration group as well as the protein expression of p-GSK 3β in α-lipoic acid medium-concentration and high-concentration groups were improved significantly （P＜0.05）. CONCLUSIONS：α-lipoic acid can improve the disorder of glucose metabolism in insulin resistant HepG 2 cells，the mechanism of which may be associated with the increase of glucose consumption ，the activities of glucose metabolism related enzymes and glycogen content ，and expression up-regulation of the phosphorylation levels of Akt and GSK 3β protein，the expression of GLUT 4 and p-GSK 3β proteins，down-regulation of the expression of GSK 3β protein.