Milk thistle and co-enzyme Q10 fortified diets lessen the nickel chloride-induced neurotoxic and neurobehavioral impairments in Oreochromis niloticus via regulating the oxidative stress response, acetylcholinesterase activity, and brain nickel content

Abstract

This study was conducted to investigate the effect of milk thistle powder (MTP) and/or co-enzyme Q10 (CoQ10) dietary supplementation on the neurobehavioral performance and brain oxidative status and histological picture in Nile tilapia (Oreochromis niloticus) reared in nickel (Ni)-polluted water. Eight groups of fish, each containing 30 fish (34.25 ± 1.02 g), were included. The experimental diets comprised basal diet, 10 g MTP/kg fortified diet, diet containing 40 mg CoQ10/kg, or MTP + CoQ10 supplemented diet. Four fish groups were cultivated in non-polluted water, and the other four groups were reared in water containing 3.6 mg Ni /L water. The trial continued for 40 days. The results revealed that MTP and/or CoQ10 addition to the O. niloticus diets significantly (P < 0.001) reversed the Ni-induced reduction in feeding frequency, middle swimming behavior, and the number of middle crossing. But, the Ni-induced aggression in terms of increased approach, chasing, fin tugging, fleeing, and mouth pushing were significantly (P < 0.001) reduced with MTP and/or CoQ10 dietary supplementation. Also, the significant (P < 0.001) depletion in the enzymatic (catalase, superoxide dismutase, glutathione peroxidase, and glutathione S transferase) and non-enzymatic (reduced glutathione) antioxidant brain content recorded in Ni-exposed fish was significantly (P < 0.001) restored by MTP and/or CoQ10 addition to their diets. Moreover, the Ni-induced significant (P < 0.001) increments in malondialdehyde content and Ni brain content of fish were significantly (P < 0.001) diminished by MTP and/or CoQ10 dietary supplementation. In addition, MTP and/or CoQ10 supplementation to O. niloticus diets significantly (P < 0.001) restored the Ni-induced depletion in acetyl-cholinesterase content in their brains. Moreover, the Ni-induced histopathological aberrations in the fish brain tissue, including choroiditis, multifocal encephalomalacia, myelencephalon neurons demyelination and vacuolation, Purkinje cell degeneration, and mesencephalon neuronal degeneration, were substantially revered by MTP and/or CoQ10 dietary supplementation. The MTP and CoQ10 co-addition to the O. niloticus diets attained the best neurobehavioral performance and brain oxidative status. These results concluded that MTP and/or CoQ10 could be considered as a beneficial dietary supplement for mitigating the Ni-induced negative impacts on the behavior and brain of the Nile tilapia.