The Effect Of IGF-1 On Expression Of P38MAPK And Biochemical Indexes In Steatosis Hepatocyte

Objective:To observe the influence of IGF-1 on expression of hepatic steatosis cell p38 MAPK and biochemical indexes of steatosis hepatocyte induced by oleic acid in order to explore the role of IGF-1 in nonalcoholic fatty liver disease, and to provide a new strategy for the prevention and treatment of NAFLD.Methods:Human hepatoma cell line Hep G2 were cultured in DMEM culture containing10% fetal bovine serum. Different concentrations of oleic acid were used to induce steatosis, and MTT method was used to explore the optimum concentration. Prior to all experiments, the Hep G2 cells were exposed to non-serum DMEM culture medium cultivation for 12 hours. The Hep G2 cells were randomly divided into 3 groups:normal control group, group induced by oleic acid, oleic acid combined with IGF-1group. Oil red O staining was used to observe the lipid deposition in each group;Western blot was used to detect the expression of p38 MAPK and p-p38 MAPK protein; the intracellular TG(triglyceride) and the Alt, AST level in supernatant of each group were determined by biochemical kit.Results:1. The model of oleic acid-induced steatosis of Hep G2 cell line can be successfully established. After oil red-O staining, lipid deposition was not observed in control group. A small amount of lipid deposition within cells was observed after24 hr culture in oleic acid-induced group with steatosis rate(10.37±1.79)%. As theculture time increased steatosis degree gradually increased, after 48 hr lipid deposition increased with steatosis rate(34.26± 7.04)% and the number came to(75.63 ±12.03)% after 72 hr,which shows the difference is statistically significant(P < 0.01).Compared with oleic acid-induced group, the steatosis degree decreased significantly in oleic acid combined with IGF-1 group after 48 hr and 72 hr.2. With the increase of culture time, TG, ALT as well as AST in oleic acid-induced group increased. At each observing time, the value of TG,ALT and AST were significantly different(P < 0.01) except the control group. Compared with the control group, the value in oleic acid-induced group was dramatically higher at24 hr,48hr and 72 hr.Nenertheless, the level of TG,ALT and AST in oleic acid combined with IGF-1 group was much lower than those in oleic acid-induced group at 48 hr and 72 hr.3. There was no significant difference on the expression of p38 MAPK at each observing time among the three groups. While, there is no p-p38 MAPK expression in the control group. In oleic acid-induced group, the expression of p-p38 MAPK was upregulated significantly at 72 hr compared with the 24 hr,48hr. However, compared to the expression of p-p38 MAPK after 72h(2.93 ± 0.13) in the oleic acid-induced group, the expression in oleic acid combined with IGF-1 group was significantly lower(1.12 ± 0.07). The difference was evident, which had statistical significance(P<0.01).Conclusion:IGF-1 not only can improve the degree of hepatocyte steatosis, but also can significantly reduce the expression of p-p38 MAPK and decrease the levels of TG,ALT and AST in steatosis hepatocyte, which suggests that IGF-1 may involve in the regulation of hepatic steatosis through the p38 MAPK signaling pathway and play an important role in the development of nonalcoholic fatty liver disease.