Toxicity assessment of chlorpyrifos and induced changes in the Ach and associated AchE activity and behavioral response in Cyprinus carpio (L.)
Kareema Ambareen1* and Mididoddi Venkateshwarlu2
1*Department of Applied Zoology, Kuvempu University, Jnana Sahyadri, Shankaraghatta, Shimoga – 577451 (India) ORCID iD: 0000-0003-1636-8320 2Department of Applied Zoology, Kuvempu University, Jnana Sahyadri, Shankaraghatta / Vice Chancellor, Tumkur University, B.H Road, Tumkur-572103 (India) ORCID iD: 0000-0001-7122-3349
ABSTRACT
Chlorpyrifos (O, O diethyl O-3,5,6-trichloro-2- pyridylphosphorothioate) second largest selling organophosphate insecticide, heavily used in the world to control agriculture and household pest. Chlorpyrifos (CPF) LC50 – 96 h was calculated as 0.318 mg/l using probit analysis based on LC50 value two sublethal concentrations of 1/5th of LC50 (0.0636 mg/l) and 1/10th of LC50 (0.0318 mg/l) were determined. The influence of CPF on the acetylcholinesterase (AChE) activity and behavioral response at both the sublethal concentrations for 7, 14, and 21 days of exposure and were allowed to recover in the pesticide-free medium for one week only after the 21st day of exposure behavioral responses and morphological deformities were studied in the experimental periods. Inhibition of AchE results in excess accumulation of acetylcholine (ACh) in cholinergic synapses leading to hyperstimulation and cessation of neuronal transmission attributed to paralysis. The carp were found under stress, there is significant mortality was observed in both the sublethal concentrations. Caudal bending and impaired morphological deformities were observed in the experimental periods. This may be a consequence due to the inhibition of brain and muscular AChE activity by chlorpyrifos-oxon via biotransformation of bioaccumulated chlorpyrifos in the tissues.