Acetylcholinesterase Enzyme (AChE) as a Biosensor and Biomarker for Pesticides: A Mini Review

Abstract

Due to the increase in pesticide usage the cost of food production has been drastically reduced worldwide. There are dangers related to the ever-increasing pesticide application especially to the non-target biota and to also to the environment at large. Pesticides bind with the active site of acetylcholinesterase (AChE) and inhibit the breakdown of acetylcholine and causes the blockage of synaptic transmission in cholinergic nerves. When AChE is inhibited, ChE accumulates and the nerve impulse cannot be stopped, leading to muscle contraction, paralysis and sometimes dead may occur. Pesticides and other chemicals that inhibit AChE activity can be able to cause abnormal behavioural patterns of the affected animals. The effects of AChE inhibition in vertebrate include vasodilation of blood vessels, slower heart rate, constriction of bronchioles and reduced secretion of mucus in the respiratory tract, intestinal cramps, secretion of saliva, sweat and tears, and constriction of eye pupil. The inhibition of the AChE activity will also definitely affect the optomotor behaviour of a fish which in turn will affect feeding capability, identification and avoidance of predators, and spatial orientation of the species. Carbamates, organophosphate and eserine are the major pesticides that inhibit the AChE activity of many animals. Cholinesterases including AChE have been considered as interesting biomarkers and biosensor for many years in the monitoring of environmental contamination. This is sensitive to selected organophosphate and carbamate pesticides and may be responding to low levels of contaminants in the environment, putatively by compounds other than or in addition to pesticides. In respect to the above AChE is regarded as a good Biosensor and biomarker in assessing pesticides and other chemical pollutants in the environment.