ACTIVATION OF DOPAMINE D-3 AUTORECEPTORS INHIBITS FIRING OF VENTRAL TEGMENTAL DOPAMINERGIC-NEURONS IN-VIVO

The firing rate of dopaminergic neurones in the ventral tegmental area of anaesthetised rats was dose-dependently (0.31-5.0 (mu g/kg i.v.) inhibited by the dopamine D-3 receptor agonist, (+)-7-OH-DPAT (7-hydroxy-2-(di-n-propylamino)tetralin). The selective dopamine D-3 receptor antagonist, (+)-S 14297 ((+)-[7-(N, N-dipropylamino)-5,6,7,8-tetrahydro-naphtho(2,3b)dihydro,2,3-furane]), dose-dependently (16-125 mu g/kg i.v.) inhibited the action of (+))-7-OH-DPAT (5 mu g/kg i.v.); its inactive distomer, (-)-S 17777 (125 mu g/kg i.v.), was ineffective. Alone, (+)-S 14297 (125 mu g/kg i.v.) did not modify the firing rate. Haloperidol(16 mu g/kg i.v.) fully reversed the action of (+)-7-OH-DPAT and, alone, significantly increased firing rate. These data suggest that inhibitory (dendritic) dopamine D-3 (auto)receptors control the electrical activity of ventral tegmental area-localised dopaminergic neurones.