λ-cyhalothrin and cypermethrin induced in vivo alterations in the activity of acetylcholinesterase in a freshwater fish, Channa punctatus (Bloch)

In the present study, the in vivo effects of λ-cyhalothrin and cypermethrin on the activity of acetylcholinesterase (AChE, EC 3.1.1.7) were evaluated for 96 h in brain, muscle and gills of Channa punctatus. Both compounds exhibited tissue specific as well as dose dependent decrease in the activity of AChE. The treated fish showed a significant decrease in the activity of AChE in brain and a lesser inhibition in muscle and gills in response to the increasing concentrations of λ-cyhalothrin as well as cypermethrin. Our results indicated that the brain was the main target organ for both insecticides, followed by muscle and gills, as determined by AChE inhibition study. However, these organs showed variations in the degree of AChE inhibition for separate treatments of both insecticides. The λ-cyhalothrin was a more potent AChE inhibitor as compared to cypermethrin. These findings indicated that apart from the established mechanism of delayed closure of sodium ion channels, these pyrethroids inhibit the activity of AChE in C. punctatus which could further aggravate their neurotoxic effects.