Effect of distigmine bromide on the central cholinergic system.

Distigmine bromide (3, 3'-[hexamethylenebis (methyliminocarbonyloxy)] bis (1-methylpyridinium) dibromide), an acetylcholinesterase (AChE) inhibitor, produced a time-dependent and dose-dependent increase in acetylcholine (ACh) levels in the medial prefrontal cortex of rats. The overt cholinergic behaviours, such as tremor, fasciculation and lacrimation, were also elicited by distigmine bromide. The onset and duration of these behaviours were reflected in the microdialysis data showing that distigmine bromide enhances cholinergic neurotransmission in rat brain. The dose of distigmine bromide eliciting increase in ACh in the medial prefrontal cortex of rats correlated well with its dose for the induction of the cholinergic behaviours. Furthermore, distigmine bromide was an equipotent inhibitor of AChE and butyrylcholinesterase (BuChE) activities in the present study. From these findings, it is suggested that distigmine bromide may produce centrally mediated behavioural signs by increasing the ACh levels in the brain, resulting from its AChE and BuChE inhibitions.