Cholinesterases: Cholinergic biomarkers for the detection of sublethal effects of organophosphorous and carbamates in Catla catla.

This study assessed the sub lethal toxic effect of Carbofuran and Profenofos on acetylycholineesterase and butyrcholinesterase in brain, gills, liver, kidney and muscle in of the indigenous fish. Biomarkers are extensively used as tools in environmental and toxicological studies to assess detrimental effects of pesticides. Sublethal adverse effects may result from exposure of fish to various concentrations of organophosphorous and carbamates. Fingerlings of Catla catla (L=90±6 mm, W= 30.00±2.00 g) were exposed to three sublethal concentrations of profenofos (0.038, 0.019 and 0.012 mg/L) and carbofuran (0.198, 0.099 and 0.066 mg/L) for the total period of two months. Both Acetylcholinesterase and butyrylcholinesterase activities were determined in brain, blood, gills, flesh, liver and kidneys in control as well as treated groups at the end of the experiment. A highly significant inhibition in the cholinesterase (acetylcholinesterase and butyrylcholinesterase) activity was observed even at the lowest exposed concentrations of profenofos and carbofuran. The minimum acetylcholinesterase activity was recorded as 4.87±0.041, 2.90±0.520, 1.07±0.040, 4.19±0.110, 31.98±0.058 and 2.98±0.012 µmol/min/g protein in brain, gills, flesh, kidney, liver and blood respectively under maximum exposure concentration of profenofos (0.038mg/L), whereas minimum butyrylcholinesterase activity was 7.13±0.088, 2.00±0.289, 5.50±0.115, 7.90±0.520, 17.19±0.052 and 18.89±0.029 µmol/min/g protein in brain, gills, flesh, kidney, liver and blood respectively under maximum exposure concentration of carbofuron (0.198mg/L). Similarly, the most detrimental concentrations of profenofos and carbofuron appeared to be 0.038mg/L and 0.198mg/L, respectively. Hence, it has been concluded that profenofos was highly toxic as compared to carbofuran  in the context of inhibition of acetylcholinesterase and butyrylcholinesterase in  all tested organs and tissues viz., brain, blood, gills, flesh, kidneys and liver. Thus affecting the functions of all these organs including metabolism and neurotransmission etc. under the exposure of both types of pesticides, no doubt the extent of effect was variable under various exposure concentrations. Owing to the highly toxic effects of presented pesticides, these pesticides are required to be monitored in the environment properly, so that their toxic effects on non-target organisms as well as human beings can be reduced.