Effect of L-histidine pretreatment on methamphetamine induced sterotyped behaviour in rats.

: Pretreatment with L-histidine precursor of histamine was found to delay the onset, shorten the duration and decrease the intensity of stereotyped behaviour induced by methamphetamine while chlorcylizine a H1 receptor blocker was found not only to potentiate methamphetamine induced sterotyped behaviour but also to block the inhibitory effect of L-histidine on methamphetamine stereotypy. Our results indicate that the central histaminergic system by exerting a modulatory influence on the striatal dopaminergic system may influence the functioning of the extrapyramidal motor system.