Bioaccumulation, histopathological and apoptotic effects of waterborne cadmium in the intestine of crucian carp Carassius auratus gibelio

Cadmium (Cd) is a highly toxic, nonessential heavy metal that has been associated with a variety of toxicological effects in both humans and animals. The main objective of this research was to investigate bioaccumulation, intestinal apoptosis, and digestive dysfunction effects of waterborne cadmium in the intestine of crucian carp Carassius auratus gibelio. Fish were exposed to 0, 100, and 500 μg/L waterborne Cd for 4 weeks, and the results showed that Cd accumulation in the intestine was significantly increased as Cd concentration increased. The intestinal structure was severely damaged, including mucosal fold length decreased, the rough endoplasmic reticulum underwent marked swelling and indistinct, and the intestinal microvilli transformed or nearly disappeared. The activities of intestinal apoptosis enzymes (Caspases 3, Caspases 8, and Caspases 9) and apoptosis rate of enterocyte cells were significantly elevated in 500 μg/L waterborne Cd group, activities of digestive enzymes (amylase and protease) were significantly decreased by 500 μg/L waterborne Cd. Overall, our results demonstrated that waterborne Cd exposure could increase Cd bioaccumulation in the intestine and destroy the intestinal digestibility of crucian carp, which in turn led to the occurrence of cell apoptosis.