Chronic toxic effects of the carbamate pesticide sevin on carbohydrate metabolism in a freshwater snakehead fish, Channa punctatus.

The effect of exposure to a sublethal concentration of the carbamate pesticide, sevin (1.05 mg/l), on biochemical parameters of blood, liver and muscle, and enzyme activities in liver, kidney, intestine, brain, gills, and muscles of the freshwater teleost fish, Channa punctatus, was studied after 15, 30 and 60 days. The alterations produced were more marked after 30 and 60 days of exposure than after 15 days; fish were hyperglycaemic and hyperlactacidemic. Glycogen content of liver and muscles decreased, but lactic acid levels of the two tissues increased. In liver, muscles, brain and gills the lactate dehydrogenase (LDH) activity was higher in pesticide-exposed fish in comparison to control fish, but the same enzyme activity was inhibited in kidney and intestine. Decreased pyruvate dehydrogenase (PDH) activity occurred in all six tissues. Succinate dehydrogenase (SDH) activity decreased in muscle at the three time periods and after 30 and 60 days in liver and brain. However, in kidney and intestine the latter enzyme activity was elevated. The results suggest that anaerobic metabolism was favoured and aerobic oxidation of pyruvate was impaired in fish exposed to sevin.