Protective efficacy of naringenin against cadmium-induced redox imbalance in Labeo rohita: an integrated biomarker approach

The protective efficacy of dietary naringenin (NG) has been investigated against the toxicity caused by cadmium chloride (CdCl₂) using biomarkers of oxidative stress in the liver, gills and kidney of Labeo rohita. The fish were exposed to environmentally relevant concentrations of CdCl₂ (0.37 and 0.62 mg/L) and simultaneously orally administered with NG (50 mg/kg bw/day) for 60 days. Tissue (gills, liver and kidney) samples were collected on days 15, 30 and 60 of the experiment and analysed for endogenous antioxidants and oxidative stress biomarkers. CdCl₂ exposure for 15 and 30 days induced the development of adaptive mechanism as demonstrated by the enhanced activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in all three tissues. However, on the 60th day, CdCl₂-induced oxidative damage was stipulated by a decline in the enzyme activities and reduced glutathione (GSH) content significantly (p < 0.05) below control levels along with enhanced levels of lipid peroxidation. Oral administration of NG in toxicant exposed fish significantly restored the altered levels of antioxidants, oxidative enzymes and lipid peroxidation. Besides, integrated biomarker response (IBR) analysis was applied by combining all the biomarkers to indicate the overall stress response index. IBR analysis confirmed the altered levels of biomarkers, the oxidative stress induced by CdCl₂ exposure and the ameliorative potential of NG. The present study suggested that NG might have protective role against Cd-induced oxidative insult which might be ascribed to the ability of NG to chelate metals and scavenge free radicals.

Ameliorating effect of ascorbic acid on fenvalerate induced ultrastructural changes in scales, erythrocytes and gills of Ctenopharyngodon idella (Valenciennes, 1844)

Fenvalerate (type II synthetic pyrethroid), widely used in agricultural practices, find its way into aquatic ecosystem through air, by runoff, or by percolation to groundwater. It is an extremely toxic insecticide for aquatic organisms especially fish. In the present study, the fenvalerate (FEN) induced toxicity and the protective efficacy of ascorbic acid (AA) against FEN in Ctenopharyngodon idella was evaluated by studying the structural alterations in scales, erythrocytes and gills. The fishes were exposed to 1.2 μg/L and 2 μg/L of FEN and orally administered with 1000 mg/kg diet of AA. The fishes were scrutinized on 15^th, 30^th and 60^th day of experiment. Scanning electron microscopic studies (SEM) of FEN-treated fish revealed extensive morphological alterations on the microstructure of scales including deformed focus, uprooted lepidonts and tubercles, hole formation and worn out calcareous material from the surface. FEN intoxication induced severe damage on erythrocytes including formation of dacrocytes, serrated spherocytes, echinocytes with oozed out cytoplasmic content, contracted plasma membrane and appearance of lobopodial projections. Ultrastructural studies in gills declared profound lesions in the form of aneurysm, loss of secondary lamellae and destructed microstructures of pavement cells. On the other hand, supplementation of AA in diet mitigated the impairment provoked by FEN on the scales, erythrocytes and gills due to its antioxidant properties.