Redox Status, Immune Alterations, Histopathology, and Micronuclei Induction in Labeo rohita Dwelling in Polluted River Water.

In this study, we measured various parameters of oxidative stress, immune response, and abnormalities in the erythrocyte nucleus of Labeo rohita inhabiting the polluted Kshipra River, India. The river water contains heavy metals in this order: Ni > Fe > Cd > Cr > Mn > Zn > Cu. Fe showed the highest accumulation in gills, liver, and gut, whereas Ni (gills and gut) and Cd (liver) were lowest accumulated. The superoxide dismutase (SOD) and catalase (CAT) were found to be increased significantly (p < 0.05) in the gills (SOD: 211%; CAT: 150%), liver (SOD: 447%; CAT: 304%), and gut (SOD: 98.11%; CAT: 58.69%) in comparison with the reference fish. However, glutathione S transferase (GST) showed significantly (p < 0.05) higher activity in the gills (25.5%) but lower activity in the liver (- 49.22%) and the gut (- 30.57%). Moreover, reduced glutathione (GSH) decreased significantly (p < 0.05) in the gills (- 46.66%), liver (- 33.20%), and gut (- 39.87%). Despite the active response of the antioxidant enzymes, the highest lipid peroxidation was observed in the liver (463%). The effect of heavy metals was also observed on the immunity of the fish, causing immunosuppression as evident by significantly (p < 0.05) lower values of acid phosphatase (- 50%), myeloperoxidase (- 48.33%), and nitric oxide synthase (- 50%) in serum. Histopathological findings showed gill lamellae shortening, hyperplasia, club-shaped lamellar tip in exposed gills and necrosis, vacuolization, and pyknosis in the exposed liver. Furthermore, polluted river water was also found to induce micronuclei (2.1%) and lobed nuclei (0.72%) in erythrocytes (0.65%). These results indicate the potential of heavy metal-induced oxidative stress and other forms of stress in inhabiting fish, highlighting the need to control the pollution of this river water.