ABSTRACT
Acephate (O,S-dimethyl acetyl phosphoramidothioate) is a racemic organophosphorus insecticide, and is effective against a wide range of insects and their larvae. The present study investigated the effect of acute sublethal dose of acephate on acetylcholine (ACh) levels and acetylcholinesterase (AChE) activity in different regions of rat brain, viz., cerebral cortex, hippocampus, cerebellum, and medulla oblongata. The LD50 of acephate (1080mg/kg) was evaluated by probit analysis method. Albino rats were divided into 4 groups with group I serving as control, while II, III and IV groups were given single, double, and multiple doses of acephate (1/5 LD50, i.e., 216mg/kg) orally, respectively. After a pre-determined time period, the rats were sacrificed by cervical dislocation, and the brain tissue was isolated in cold conditions to carry out estimations of ACh content and AChE activity. In contrast to increased AChE inhibition, ACh levels were elevated in all brain regions in a dose-dependent manner.