Detection of Multiple Cytochrome P450 in Hepatic Tissue of Heteropneustes fossilis (Bloch) Exposed to Cypermethrin

Abstract

Cypermethrin (alpha-cyano-3-phenoxybenzyl ester of 2,2-dimethyl-3-(2,2-dichlorovinyl) cyclopropane carboxylic acid) is a synthetic pyrethroid. It is one of the most widely used pesticide in commercial agricultural applications because of its high effectiveness against target species. Beside its target toxicity it is also highly toxic to other non-target species like fish, bees and aquatic insects. The aim of this study was to detect the presence of cytochrome P450 (CYP 450) in the hepatic microsomes of Heteropneustes fossilis upon exposure to cypermethrin. The 96 h LC50 value for each exposure route was calculated and two groups were treated, with one group receiving a single IP (intraperitoneal) injection for 96 h (0.030 mg/kg body weight) and the other group with 1/3 sub-lethal concentration (1.2 μg/l) of the LC50 value in water for 15 days. Activities of the enzymes ethoxyresorufin-o-deethylase (EROD), N,N-dimethylaniline demethylase, aniline hydroxylase and erythromycin demethylase mediated respectively by the isozymes CYP1A, CYP2B, CYP2E1 and CYP3A4 were studied. The liver somatic index (LSI) was also calculated to determine the physiological status of the fish. Activities of CYP1A, CYP2B and CYP2E1 enzymes increased significantly while that of CYP3A4 enzyme inhibited as compared to control. Total CYP 450 content was also significantly induced in both the treated groups. The increase in activities of CYP P450 isozymes could be used as a biomarker to indicate the pollution of an aquatic environment by the pesticide.