Carbamazepine at environmentally relevant concentrations caused DNA damage and apoptosis in the liver of Chinese rare minnows (Gobiocypris rarus) by the Ras/Raf/ERK/p53 signaling pathway.

Abstract

To assess genetoxicity and the underlying mechanisms of carbamazepine (CBZ) toxicity in fish, adult Chinese rare minnows (Gobiocypris rarus) were exposed to 1, 10, and 100μg/L CBZ for 28d. Comet assays indicated that hepatic DNA damage was significantly increased in groups of minnows exposed to CBZ at all concentrations in a dose-dependent manner compared to those of the control groups (p<0.05). Liver levels of 8-hydroxydeoxyguanosine (8-OHdG) were significantly increased at 10 and 100μg/L CBZ (p<0.05). TUNEL assays indicated that the average apoptotic rates of the livers of female and male minnows were significantly increased following exposure to CBZ at all concentrations for 28d (p<0.05). Significant increases in caspase 3 and 9 activities after CBZ exposure at all concentrations and caspase 8at 10 and 100μg/L CBZ exposure reflected the presence of mitochondrial apoptosis (p<0.05). The mRNA levels of gadd45a, mdm2, casp3 and casp9 in female and male minnows exposed to CBZ at all concentrations were significantly increased compared with those in the control groups (p<0.05). Significant increases in the levels of p21 in female minnows exposed to 1 and 100μg/L CBZ, p53 in female minnows at all CBZ treatments and bcl2 in male minnows exposed to 1 and 100μg/L CBZ were observed, indicating p53 pathway activation. The inhibition of ras levels in females and males exposed to CBZ at all concentrations and increased levels of raf1 in males exposed to CBZ at all concentrations indicated Ras/Raf1/MAPK (ERK) activation. Therefore, the present study demonstrates that CBZ at environmentally relevant levels induces DNA damage and apoptosis in Chinese rare minnows by the Ras/Raf/ERK/p53 signaling pathway.