Acute exposure to the biopesticide azadirachtin affects parameters in the gills of common carp (Cyprinus carpio)

The biopesticide, azadirachtin (Aza) is less hazardous to the environment, but may cause several toxic effects in aquatic organisms. The Cyprinus carpio (n = 12, for all concentrations) after 10 days of acclimation under controlled conditions, were exposed at 20, 40, and 60 μL/L of Aza during 96 h. After this period, fish were anesthetized and euthanized then mucus layer and gills collected. In this study, the effects of exposure to different Aza concentrations were analysed through a set of biomarkers: Na+/K+-ATPase, lipid peroxidation (TBARS), protein carbonyl (PC), superoxide dismutase (SOD), glutathione-S-transferase (GST), catalase (CAT), glutathione peroxidase (GPx), non-protein thiols (NPSH), ascorbic acid (AsA) and histological parameters and, yet, protein and glucose concentration in the surface area of mucous layer. Na+K+-ATPase was inhibited at 40 and 60 μL/L compared to control. TBARS decreased at 40 μL/L compared to control. PC, SOD and GST increased at 60 μL/L in comparison to control. CAT increased at 20 and 60 μL/L, and GPx increased in all Aza concentrations compared to control. NPSH decreased and AsA increased in all concentrations in comparison to control. Histological analyses demonstrated an increase in the intensity of the damage with increasing Aza concentration. Alterations in histological examination were elevation and hypertrophy of the epithelial cells of the secondary filament, hypertrophy and hyperplasia of the mucous and chlorate cells and lamellar aneurism. Glucose and protein concentrations in mucus layer increased at 60 μL/L compared to control. In general, we suggest that 60 μL/L Aza concentration affected several parameters causing disruptions carp metabolism.