HISTOPATHOLOGICAL LESIONS AND OXIDATIVE STRESS IN THE GILL AFTER CHLORPYRIFOS EXPOSURE IN THE FRESHWATERFISH, PSEUDETROPLUS MACULATUS (BLOCH, 1795)

Abstract

The present study aims to evaluate the histopathological lesions and oxidative stress responses of
chlorpyrifos in the gill of freshwater teleost fish, Pseudetroplus maculatus. Chlorpyrifos was
exposed to fish at sublethal concentration (one-tenth of LC50-96 h; 0.661µg/L) for 24, 48, 72 and
96 h maintaining the control group. The weight of gill decreased significantly only after 96 h of
chlorpyrifos treatment. The activity of superoxide dismutase increased significantly (P<0.05)
after 48 h in time-dependent manner, and the catalase activity was significantly (P<0.05)
increased at 72 and 96 h of chlorpyrifos exposure. The level of hydrogen peroxide increased
significantly (P<0.05) after 48 h and the lipid peroxidation was found to be increased
significantly (P<0.05) immediately after 24 h of the toxicant exposure in time-dependent manner.
Histopathological lesions in the gill after 96 h of chlorpyrifos exposure include degeneration of
gill arches, epithelial uplifting, hyperplasia and aneurysm in primary lamellae, degeneration and
necrosis of the secondary lamellae and vacuolization. The present study conclude that acute
exposure to chlorpyrifos at 0.661µg/L concentration has the ability to induce oxidative stress as
well as damages the gill tissues of fish and those effects are time-dependent.