Biochemical alterations in euryhaline fish, Oreochromis mossambicus exposed to sub-lethal concentrations of an organophosphorus insecticide, monocrotophos.

The euryhaline fish, Oreochromis mossambicus was exposed to sub-lethal concentration (1.15 mg l(-1)) of a organophosphorus insecticide, monocrotophos (MCP) for 30 days and allowed to recover for seven days. Alanine aminotransferase (ALAT), aspartate aminotransferase (AAT), acid phosphatase (AcP), alkaline phosphatase (ALP), glycogen, lactate dehydrogenase (LDH), Reduced glutathione (GSH), gluthathione-S-transferase (GST) and acetylcholinesterase (AChE), were assayed in plasma and different tissues at regular intervals of day -3, -7, -15, -30 and after recovery period of seven days. The ALAT and AAT activities were increased in plasma and kidney, where as liver and gill showed decrease. Increase in AcP and ALP activities were observed in plasma, gill and kidney, and reduction of 42% and 50% was observed in liver. Glycogen was depleted in plasma, liver and gill indicates of typical stress related response of the fish with pesticide. LDH activity was decreased in liver and muscle, indicating tissue damage and muscular harm, but a significant increase in LDH activity in gill and brain was observed. Depletion in GSH activity was observed in all the tissues, there by enhancing the lipid peroxidation resulting in cell damage. The induction in hepatic GST levels indicates the protection against the toxicity of xenobiotic-induced lipid peroxidation. There was a significant recovery in all the above biochemical parameters studied in plasma and different tissues, after seven days recovery period. These results revealed that MCP affects the intermediary metabolism of O. mossambicus and that the assayed enzymes can work as good biomarkers of organophosphorus contamination.