Zetidoline blocks dopamine autoreceptors in the rat substantia nigra

Zetidoline, applied microiontophoretically onto neurones in the substantia nigra, zona compacta of anaesthetized rats, reversibly blocked the depressant effect of iontophoretically-applied dopamine. The inhibitory actions of gamma-aminobutyric acid (GABA) and glycine and the excitatory action of glutamate were unaffected by the antagonist. Zetidoline applied by bath perfusion, was similarly an antagonist of the inhibitory effect of bath applications of dopamine on neurones in the zona compacta of slices of substantia nigra; the pA2 for zetidoline in this preparation was 7.0.