Protective effect of metformin on BPA-induced liver toxicity in rats through upregulation of cystathionine β synthase and cystathionine γ lyase expression

Abstract

Human exposure to bisphenol A (BPA) is unavoidable in daily life. Recently, research has showen that BPA could induce oxidative imbalance, thereby causing reproductive toxicity and liver dysfunction. Accumulated evidence has demonstrated that metformin possesses strong anti-oxidative properties. This study aimed to study the mechanism underlying the hepatic-protective effect of metformin on liver injury induced by BPA in rats via the UPLC-MS/MS metabolomics approach. Forty-two male rats were randomly divided into six groups (n = 7), namely the saline group (control), the corn oil group (vehicle), the metformin group (Met), the bisphenol A group (BPA), the bisphenol A and metformin group (BPA + Met), and the bisphenol A and diammonium glycyrrhizinate (positive control) group (BPA + DG). Serum was collected for biochemical analysis and metabolomics, and liver tissue was collected for histopathology and metabolomics in each group. We found that metformin could significantly reduce the levels of liver function enzymes (ALT, AST and GGT) and ameliorate inflammatory cell infiltration and hepatocyte necrosis induced by BPA. On the other hand, metformin could significantly enhance the total antioxidant capacity in BPA rats. Notably, metabolomics data indicated that the principal altered metabolic pathways based on the 26 differential metabolites in liver tissue, and 21 in serum among vehicle, BPA and BPA + Met groups, respectively, including cysteine and methionine metabolism, glutathione metabolism, and arginine biosynthesis and purine metabolism. Additionally, metformin significantly increased cystathionine β synthase (CBS) and cystathionine γ lyase (CSE), thus reducing serum levels of homocysteine and increasing hepatic levels of cysteine and glutathione in BPA-treated rats. Overall, this study's results provided new insights into the role and mechanism of metformin in BPA-induced liver injury in rats.