12. Impact of Cypermethrin on Selected Enzymes in Tissues of <i>Heterobranchus bidorsalis</i>
Heterobranchus bidorsalis (mean total length 31.50 ± 2.32 cm SD; mean weight 241.25 ± 30.39 g SD) was
exposed to cypermethrin (0.005, 0.0075, 0.010, 0.125 and 0.0150 p.p.m.) for 23 days to determine the activity of
transaminases (alanine transaminase, ALT; aspartate transaminase, AST) the phosphatase, alkaline phosphatase, ALPin the gill, kidney, liver and muscle tissue. The activity of ALTin the gill at 0.005 and 0.010 p.p.m. were lower (P > 0.05) than the control, whereas elevated activity above the control were recorded at the other concentrations. AST activity was excited 11.36–220.45% above the control value at all the concentrations. ALP activity was inhibited below the control value with the highest inhibition, 40.46% at 0.010 p.p.m. ALTactivities in the kidney at all the exposure concentrations were elevated 33.33% and 66.67% above the control at 0.005–0.010 p.p.m. and 0.0125–0.0150 p.p.m., respectively. Inhibition below the control was recorded in all the exposure concentrations for AST and ALP. ALT and AST activities in the liver were inhibited below their respective control values. ALP activity was inhibited at 0.0075 and 0.0150 p.p.m. (44.12 and 23.53%, respectively, below control value), but excited at the other concentrations with a peak, 33.83% at 0.010 p.p.m. In the muscle, 12.68% and 23.94% elevation above the control were recorded at 0.0125 and 0.0150 p.p.m., respectively, for ALT with a decrease in the lower concentrations. There was excitation of AST activity at 0.0050, 0.010 and 0.015 p.p.m., and inhibition at 0.0075 and 0.0125 p.p.m. relative to the control value. There was general inhibition of ALP activity in the muscle of treated fish below the control except at 0.010 p.p.m. The usefulness of the enzymes as biomarkers of cypermethrin toxicity appeared to be concentration and tissue dependent, and can be effectively used to assess the impact of the agrochemical on the fish.