Oxidative stress, neurotoxicity, and immune responses in juvenile Sobaity seabream ( Sparidentex hasta ) following waterborne selenium exposure

Abstract

Selenium (Se) is a crucial element involved in various physiological processes and is essential for maintaining an active endogenous anti-oxidant system. This study aimed to examine the effects of different Se concentrations on oxidative stress, neurotoxicity, and immunity in juvenile Sobaity seabream ( Sparidentex hasta ). Juvenile S. hasta , averaging 14.6 ± 1.7 cm in length and 87.4 ± 5.6 g in weight, were exposed to waterborne Se concentrations from 0 (control group) to 400 µg L ⁻¹ for 2 and 4 weeks. Concentrations of 320 and 400 µg L ⁻¹ were considered for the toxicity threshold test. Results indicated a significant increase in superoxide dismutase and glutathione S -transferase activity in the liver and gills following exposure. Additionally, the highest Se levels led to a notable rise in glutathione in both tissues. Catalase activity varied across different fish organs, with the liver showing the highest levels. Neurotoxicity assessments revealed that Se exposure decreased acetylcholinesterase activity in muscle and brain tissues. Moreover, high Se concentrations significantly boosted plasma and kidney lysozyme activity, indicating enhanced non-specific immune responses, although they also reduced peroxidase and anti-protease activities. These changes serve as effective indicators for evaluating Se toxicity in aquatic ecosystems.