Purslane leaf powder dietary supplementation rescues cadmium-induced disruption of behavior, antioxidant status, and expression of tight junction genes, in the brain of Nile tilapia (Oreochromis niloticus)

Abstract

This study examined the effects of supplementing the Nile tilapia (Oreochromis niloticus) diet with purslane (Portulaca oleracea L.) leaf powder (PLNP, 10 g/kg) on neurobehavioral performance, brain oxidative status, tight junction mRNA expression, and brain histology in fish exposed to waterborne cadmium (Cd, 50 μg /L) for 60 days. Adding PLNP to the diet ameliorated the Cd-induced decline in ingestive behavior and swimming behavior, and reversed the Cd-induced increase in aggressive behavior. The significant decrease in the non-enzymatic (reduced glutathione) and enzymatic (catalase and superoxide dismutase) brain antioxidants detected in Cd-exposed fish was eliminated by dietary PLNP. PLNP supplementation also led to a decrease in brain malondialdehyde content, which was elevated by Cd exposure. In addition, dietary PLNP increased brain acetylcholinesterase content, upregulated mRNA expression of tight junction (zo-2, claudin-4, and zo-1) and oxidative stress genes (sod-2, gpx, and nrf-2), and downregulated apoptotic genes (p53, caspase-9, caspase-8, and caspase-3) in the brain, relative to the alterations in these parameters caused by Cd exposure. Furthermore, the Cd-induced histological changes in the Nile tilapia brain were ameliorated by PLNP dietary supplementation. In light of these findings, PLNP may be a useful dietary supplement for reducing the harmful effects of Cd on the brain and behavior of Nile tilapia.