Recent evidence has shown in membrane preparations that the binding of one ligand to its receptor is able to modify the binding parameters of a second receptor (receptor-receptor interactions), allowing the modulation of incoming signals onto a neuron. To further understand the gamma-aminobutyric acid (GABA)-dopamine (DA) interactions in the neostriatum we have carried out experiments to explore whether an activation of the GABA(A) receptor could affect the binding characteristics of the D-2 DA receptor in membrane preparations of the rat neostriatum. The results show that GABA (30-100 nM) significantly increases the dissociation constant of the high affinity (K-H) D-2 DA binding site (labelled with the selective D-2 DA receptor antagonist [H-3]raclopride and that such an effect is fully counteracted by the GABA(A) receptor antagonist bicuculline (1 mu M). It is suggested that such putative GABA(A)/D-2 receptor-receptor interactions may take place in the somato-dendritic membrane of the striato-pallidal GABA neurons and that it may modulate the inhibitory effects of DA on these neurons, mediated via D-2 receptors.
Última actualización: 15/12/2017