Swimming exercise ameliorates insulin resistance and nonalcoholic fatty liver by negatively regulating PPARγ transcriptional network in mice fed high fat diet
Yong Zhang, Jie Xu, Di Zhou, Tingting Ye, Puqing Zhou, Zuofeng Liu, Xinyuan Liu, Zinan Wang, Tianmiao Hua, Zhenghao Zhang, Qingyan Sun
Abstract
BACKGROUND: Recent findings elucidated hepatic PPARγ functions as a steatogenic-inducer gene that activates de novo lipogenesis, and is involved in regulation of glucose homeostasis, lipid accumulation, and inflammation response. This study delved into a comprehensive analysis of how PPARγ signaling affects the exercise-induced improvement of insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD), along with its underlying mechanism. METHODS: Chronic and acute swimming exercise intervention were conducted in each group mice. IR status was assessed by GTT and ITT assays. Serum inflammatory cytokines were detected by Elisa assays. PPARγ and its target genes expression were detected by qPCR assay. Relative protein levels were quantified via Western blotting. ChIP-qPCR assays were used to detect the enrichment of PPARγ on its target genes promoter. RESULTS: Through an exploration of a high-fat diet (HFD)-induced IR and NAFLD model, both chronic and acute swimming exercise training led to significant reductions in body weight and visceral fat mass, as well as hepatic lipid accumulation. The exercise interventions also demonstrated a significant amelioration in IR and the inflammatory response. Meanwhile, swimming exercise significantly inhibited PPARγ and its target genes expression induced by HFD, containing CD36, SCD1 and PLIN2. Furthermore, swimming exercise presented significant modulation on regulatory factors of PPARγ expression and transcriptional activity. CONCLUSION: The findings suggest that swimming exercise can improve lipid metabolism in IR and NAFLD, possibly through PPARγ signaling in the liver of mice.