Seafood-based dietary cadmium exposure triggers physiological stress and gene dysregulation in zebrafish

The present study investigated the effects of seafood-related dietary cadmium (Cd) levels on the survival, growth, biochemical constituents, digestive and metabolic enzyme activities, and antioxidant status of zebrafish (Danio rerio) over a 45-day period. Zebrafish were fed Artemia flakes (AF) containing 0 mg kg^-1 Cd (control) and four environmentally relevant concentrations representative of seafood contamination: 0.3 mg kg^-1 (permissible limit), 1 mg kg^-1 (minimum), 3 mg kg^-1 (median), and 5 mg kg^-1 (maximum). The results revealed significant Cd-induced toxicity across multiple biological parameters. Survival rate, growth performance, food index, biochemical constituents, and digestive enzyme activities exhibited marked alterations in zebrafish exposed to varying dietary Cd levels compared with the control. Antioxidant and metabolic enzyme activities showed dose-dependent responses, with stimulation at lower Cd levels and inhibition at higher concentrations. Elevated lipid peroxidation observed at higher Cd doses indicated oxidative stress, suggesting that reduced antioxidant capacity leads to increased free radical generation and lipid membrane damage. Gene expression analysis further showed upregulation of sod1, cat, nqo1, and ogg1 at low Cd levels, followed by sharp suppression of these genes. Dose dependent dysregulation was recorded in mbpa and gfap genes, whereas, strong downregulation of gsta1 and apex1 was observed in zebrafish at higher Cd exposure indicating neurotoxicity and impaired genomic repair under severe stress. Overall, the findings demonstrate that chronic exposure to seafood-derived dietary Cd can adversely affect the biological and physiological responses of zebrafish. This implies potential health risks for seafood consumers and highlights the need for regular monitoring of heavy metal contamination in seafood to ensure consumer safety.