The role of insulin and glucose in goose primary hepatocyte triglyceride accumulation

Abstract

SUMMARY In order to obtain some information on how fatty liver arises in geese, we investigated the role of insulin and glucose in triglyceride (TG) accumulation in goose primary hepatocytes. Goose primary hepatocytes were isolated and treated with insulin and glucose. Compared with the control group, 100 and 150 nmol l–1 insulin increased TG accumulation, acetyl-CoA carboxylase-α (ACCα) and fatty acid synthase (FAS)activity, and the mRNA levels of sterol regulatory element-binding protein-1(SREBP-1), FAS and ACCα genes. Insulin at 200 nmol l–1 had an inhibiting effect on TG accumulation and the activity of ACC and FAS, but increased the gene expression of SREBP-1, FAS and ACCα. We also found that high glucose (30 mmol l–1)increased the TG level, ACC and FAS activity, and the mRNA levels of SREBP-1 and FAS. However, there was no effect of high glucose on ACCα mRNA level. In addition, the interaction between insulin and glucose was observed to induce TG accumulation, ACC and FAS activity, and gene expression of SREBP-1, FAS and ACCα, and increase SREBP-1 nuclear protein level and binding of nuclear SREBP-1 and the SRE response element of the ACCgene. The result also indicated that the glucose-induced TG accumulation decreased after 96 h when the hepatocytes were cultured with 30 mmol l–1 glucose. In conclusion, insulin and glucose may affect hepatic lipogenesis by regulating lipogenic gene expression and lipogenic enzyme activity in goose hepatocytes, and SREBP-1 might play an important role in the synergetic activation of lipogenic genes. We propose that the utilization of accumulated TG in hepatocytes is the reason for the reversible phenomenon in goose hepatocellular steatosis.