Abstract

Nitrite represents a prevalent environmental challenge in aquaculture. This study investigated the protective mechanism of dietary coated sodium selenite (CSS) on grass carp muscle tissue damage mediated by nitrite exposure, with a specific focus on mitochondrial-endoplasmic reticulum contact (MERC) stability. Grass carp were maintained for 8 weeks on diets supplemented with CSS at five selenium (Se) levels (0.028, 0.25, 0.50, 0.75, and 1.00 mg/kg), after which they were subjected to a 96-h nitrite exposure. Results indicated that Se mitigated the perturbations in blood parameters and the decrease in muscle quality under nitrite stress. Additionally, Se maintained MERC integrity, potentially through the mitigation of mitochondrial calcium (Ca 2+ ) overload. It also down-regulated the endoplasmic reticulum (ER) stress markers and apoptosis-related factors. These results suggested that Se supplementation could serve as an effective preventive strategy against muscle quality degradation and muscle damage induced by environmental nitrite in aquaculture.