AUTORADIOGRAPHIC LOCALIZATION OF GAMMA-AMINOBUTYRIC ACIDA RECEPTORS WITHIN THE VENTRAL TEGMENTAL AREA

Destruction of intrinsic neurons in the ventral tegmental area (VTA) with the excitotoxin, quinolinic acid produced a significant decrease (80%) in [H-3]muscimol binding to GABA(A) receptors within the parabrachial pigmented and paranigral nuclei of the VTA. Selective destruction of the dopaminergic neurons with 6-hydroxydopamine (6-OHDA) did not reduce [H-3]muscimol binding within the VTA. However, the destruction of dopaminergic neurons did produce an increase (20%) in [H-3]muscimol binding contralateral to the lesion, suggesting a reduction in the GABAergic innervation to this region. Additionally, destruction of the VTA afferents with quinolinic acid injections in the medial accumbens failed to produce alterations in [H-3]muscimol binding within the VTA. These results are consistent with the predominant localization of GABA(A) receptors to non-dopaminergic neurons intrinsic to the VTA.