[Effect of the atypical neuroleptics karbidin and sulpiride on the synaptosomal tyrosine hydroxylase of the corpus striatum of rats].

An in vitro study was made of the influence of the atypical neuroleptics sulpiride and carbidine on the activity of synaptosomal tyrosine hydroxylase (TH) of the rat brain striatum. Dopamine was applied as an inhibitor of tyrosine hydroxylation (10(-6) M), dopamine uptake was blocked by nomifensine (10(-5) M). The experiments were performed in two versions: in a medium containing common (5 mM) and depolarizing concentration of potassium ions. In both the cases sulpiride did not exert any noticeable effect on TH activity but significantly lowered the inhibitory action of dopamine. In a medium containing 30 mM potassium, carbidise inhibited the rate of TH hydroxylation and enhanced the inhibitory action of dopamine on TH activity under blockade of its uptake by nomifensine. It is assumed that the mechanisms of the action of carbidine and sulpiride are different.