The effect of alpha-adrenergic receptor stimulant drugs on amphetamine or apomorphine-induced stereotypy in rats.

Clonidine, xylometazoline and naphazoline given ip cause a transition from sniffing to licking or gnawing stereotypy induced by amphetamine or apomorphine. Methoxamine, phenylephrine and in a lesser degree noradrenaline (all given ivc) inhibit licking and gnawing stereotyped behavior. Biochemical results correlate with the depressant action of clonidine and naphazoline on central noradrenergic neurotransmission and also with the stimulant action of methoxamine and phenylephrine on noradrenergic system. The both groups of alpha-adrenergic agonists seem to modify both the central dopaminergic and noradrenergic system activity in the same direction. It is suggested that this action can play a role in observed modification by alpha-sympathomimetic drugs of responses to dopamine agonists. However, the influence of alpha-sympathomimetics on other brain systems must be also taken into consideration.