Detection of Hepatic Cytochrome P450 as Biomarkers of Cypermethrin Toxicity in Fish, Channa punctatus (Bloch)

Cypermethrin being a synthetic pyrethroid, 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. In this
study, Channa punctatus was treated with sub-lethal concentration of cypermethrin (6.6 μg/L) for 5,
10 and 15 days and its effect on total CYP 450 and the activity of hepatic CYP450 isoforms
measured. Total CYP450 content and CYP1A mediated EROD activity was significantly induced
(p<0.05; p<0.01) in all three treated groups compared to control whereas only 15 days treated group
showed significant induction in CYP2B mediated N,N- dimethylaniline demethylase activity (p<0.05).
CYP2E1 mediated aniline hydroxylase activity showed only a marginal increase while there was
significant inhibition of CYP3A4 mediated erythromycin demethylase activity (p<0.05; p<0.01). Liver
somatic index (LSI) also showed a marginal increase in all the treated groups. Results showed
differential induction of CYP1A, CYP2B, CYP2E1 and inhibition of CYP3A4 isoform due to
cypermethrin treatment in C. punctatus. Comparisons of control and cypermethrin-exposed hepatic
microsomes indicated increased enzymatic activity and a 53.5 kDa protein of increased intensity was
observed after SDS-PAGE of microsomal protein. The molecular weight of this protein was similar in
size to that obtained by heme staining of SDS-PAGE gels by TMPD (N,N,N’N’ -tetramethyl-pphenylenediamine).
The study clearly showed CYP1A isoform as the most responsive and important
biomarker for monitoring the aquatic pollution.