Reversion of hepatic steatosis by exercise training in obese mice: The role of sterol regulatory element-binding protein-1c

摘要

Aim: The dysregulation of regulatory element-binding protein-1c (SREBP-1c) is associated with hepatic steatosis. However, effects of exercise on SREBP-1c protein level in liver have not been investigated. Thus, in this study we investigated if reversion of the hepatic steatosis-induced by exercise training is related with levels of SREBP-1c. Main methods: Mice were divided into two groups: control lean mice (CT), fed on standard rodent chow, and obese mice (HF), fed on a high-fat diet for 2 months. After this period obese mice were divided in two groups: obese mice and obese mice submitted to exercise (HF + EXE). The HF + EXE group performed a running program of 50 min per day, 5 days per week, for 8 weeks. Forty-eight hours after the last exercise session, biochemical, immunoblotting, histology and immunohistochemistry analyses were performed. Key findings: Livers of HF mice showed increased SREBP-1c, FAS (Fatty Acid Synthase), SCD1 (Stearoyl-CoA Desaturase1) and CPT1 (Carnitine Palmitoyl Transferase1) protein levels (3.4, 5.0, 2.6 and 2.9 times, respectively), though ACC (Acetyl-CoA Carboxilase) phosphorylation dropped 4.2 times. In livers of HF + EXE, levels of SREBP-1c, FAS, SCDI and CPTI decreased 2.1, 1.9, 1.8, and 2.7 times, respectively), while ACC phosphorylation increased 3.0 times. Lower SREBP-1c protein levels after exercise were confirmed also by immunohistochemistry. Total liver lipids content was higher in HF (2.2 times) when compared to CT, and exercise training reduced it significantly (1.7 times). Significance: Our study allows concluding that the reduction in SREBP-1c protein levels is associated with steatosis reversion induced by exercise training.