Activation of tuberoinfundibular dopamine neurons following the acute administration of atypical antipsychotics.

The activity of tuberoinfundibular dopamine neurons, as judged from dihydroxyphenylacetic acid (DOPAC) concentrations or the accumulation of dihydroxyphenylalanine (DOPA) in the median eminence after the inhibition of DOPA decarboxylase, was increased following the acute administration of the purported atypical antipsychotics clozapine, thioridazine, melperone, setoperone, and RMI 81582. In contrast, the activity of these hypothalamic dopamine neurons was not acutely altered by the typical antipsychotics haloperidol, chlorpromazine, fluphenazine, and cis-flupentixol or by SCH 23390. The acute stimulatory effect of the atypical antipsychotics on the activity of tuberoinfundibular dopamine neurons was effectively antagonized by the D1 agonist SKF 38393 but not by the D2 agonist quinpirole. The production of an acute activation of tuberoinfundibular dopamine neurons, which appears to be sensitive to D1 receptor activation, may be an effect that distinguishes typical and atypical antipyschotic agents.