Alteration of lipid metabolism, autophagy, apoptosis and immune response in the liver of common carp (Cyprinus carpio) after long-term exposure to bisphenol A

Bisphenol A (BPA), as a phenolic compound, is harmful to human health, and its residue in the aquatic environment also threatens the health of aquatic animals. In this research, the toxicity effects of BPA on liver tissues were evaluated in common carp (Cyprinus carpio) after long-term exposure. Fish were exposed to five concentrations of BPA (0, 0.01, 0.1, 0.5 and 2 mg/L) for 30 days. The blood and liver tissues were gathered to analyze biochemical indices and genes transcription levels. The data related to lipid metabolism showed that BPA exposure increased serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) levels, upregulated the expressions of fatp1, pparγ, fas, atgl, hsl, pparα, cpt1b, acox-1, and downregulated the expression of dgat1 in liver. Antioxidative parameters displayed a reduced antioxidant ability and increased lipid peroxidation after BPA exposure. Meanwhile, the upregulations of nrf2, ho-1, cyp1a and cyp1b genes revealed an adaptive response mechanism against oxidative stress-induced adverse effects. After 30 days of exposure, BPA induced apoptosis and endoplasmic reticulum stress (ERS) via upregulating the expression levels of apoptosis and ERS-related genes and increasing Ca2+ concentration in liver. Moreover, the downregulation of mtor and the upregulation of atg3, atg7, tfeb, uvrag and mcoln1 indicated that BPA could influence the normal process of autophagy. Furthermore, BPA exposure activated toll like receptors (TLRs) pathway to mediate the inflammatory response. Our results demonstrated that BPA exposure disturbed lipid metabolism, and induced oxidative stress, ERS, apoptosis, autophagy and inflammatory response in the liver of common carp. These findings contributed to the understanding of hepatotoxicity mechanism induced by BPA in fish.