Ammonia stress–induced apoptosis by p53–BAX/BCL-2 signal pathway in hepatopancreas of common carp (Cyprinus carpio)

Ammonia is the main environmental pollutant in aquaculture that has a negative impact on the healthy cultivation of common carp. The effects of antioxidant capacity, histopathology, and related gene expression of common carp (Cyprinus carpio) under ammonia stress (2.6 mM ammonia concentration, 168 h) were studied. In the study, ammonia stress can lead to oxidative stress in common carp, which is related to the regulation of SOD, GSH-PX, and CAT activities. Histopathology and TUNEL assays confirmed that apoptosis occurred in the hepatopancreas after ammonia stress, and the rate of apoptosis increased significantly with increasing exposure time (P < 0.05). We found the mRNA expression of p53, BAX, caspase-9, and caspase-3 were significantly enhanced (P < 0.05), and the transcriptional expression of BCL-2 was significantly inhibited (P < 0.05) in the late stage of ammonia exposure (96 h and 168 h). The results showed the apoptosis in the hepatopancreas of common carp under ammonia stress may be mediated by oxidative stress through the p53–BAX/BCL-2 apoptosis signal pathway.