Acute exposure of Cr and Cu induces oxidative stress, genotoxicity and histopathological alterations in snakehead fish Channa punctatus

Aim: This study aimed to investigate the oxidative stress, genotoxicity and histopathology after sub-lethal exposure of chromium (Cr6+) and copper (Cu+2) to common food fish Channa punctatus. Metal exposure to fishes of River Ganga is a very common phenomenon due to their ubiquitous nature and through discharge of domestic and industrial waste into the river water. Methodology: An in-vitro experiment was performed to study ill effects of metallic stressors on fish. Fishes were divided into seven groups. Group I served as control, Group II, III, IV as 1/20th ,1/10th and 1/5th of 96 hr-LC50 of Cr6+. Group V, VI and VII were similarly treated with Cu at 1/20th, 1/10th and 1/5th of 96 hr LC50 of Cu+2, respectively. All the treatments were done for 15, 30 and 45 days of exposure period. Genotoxicity was evaluated by micronuclei (MN) induction. Enzymatic and non-enzymatic oxidative stress markers, including reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione reductase (GR), and glutathione peroxidase (GPx) were evaluated. Histopathological studies of liver and kidney tissue were also performed. Results: Stress biomarkers were more profound in fishes of chromium treated groups in comparison to copper. Particularly, SOD and CAT showed a significant hike in the activity levels. ROS levels in blood cells increased significantly (p < 0.05) in all the treated groups (Group II, III, and IV) in a dose dependent manner as compared with control (Group I). There was significant induction in micronuclei (MN) frequency in all the treated groups for both the metals. The highest frequency of MN induction was recorded in Group IV after 96 hr of the exposure period.Significant histological alterations were observed in liver and kidney of treated fish, changes were more pronounced in chromium treated fish than copper. Interpretation: Acute exposure of chromium and copper induces ROS and generates oxidative stress mediated genotoxicity and histopathological perturbations in the prime organs of fish.Cr and Cu induces the changes in the production and accumulation of enzymatic antioxidant system for the regulation and scavenging of ROS induced by Cr and Cu. Key words: Channa punctatus, Genotoxicity, Histology, Heavy metals, Micronuclei, Oxidative stress