Redox driven inflammatory and senescence-associated changes in Channa striata exposed to insecticide Fipronil with ascorbic acid-mediated modulation

Fipronil (FIP), a widely used second-generation phenylpyrazole insecticide, is known for its broad-spectrum and systemic activity. The present study evaluated the toxic effects of commercial FIP (80% WG) on the striped snakehead fish, Channa striata , following 15, 30, and 45 days of exposure, and assessed the protective role of ascorbic acid (AA). Fish were divided into six groups: control, AA control (50 mg L⁻ 1 ), 0.002 mg L⁻ 1 FIP, 0.002 mg L⁻ 1 FIP + AA, 0.004 mg L⁻ 1 FIP, and 0.004 mg L⁻ 1 FIP + AA. FIP exposure significantly ( p < 0.05 ) increased erythrocytic ROS levels and protein carbonyl content, while GST activity declined markedly. SOD and CAT activities exhibited biphasic responses during the exposure period. Significant ( p < 0.05 ) alterations were observed in senescence-associated gene expression profiles. Correlation and Principal Component Analysis revealed associations among oxidative stress markers, DNA damage response genes, inflammatory signaling, antioxidant defense, and senescence-associated gene expression. Co-exposure with AA partially alleviated oxidative stress and moderated gene expression changes, indicating its protective potential against FIP-induced toxicity.