Dopamine D-1 receptor-mediated facilitation of GABAergic neurotransmission in the rat strioentopeduncular pathway and its modulation by adenosine A(1) receptor-mediated mechanisms

By using in vivo microdialysis it was found that one of the main functions of striatal dopamine D-1 receptors is to selectively facilitate GABAergic neurotransmission in the 'direct' strioentopeduncular pathway. D-1 receptors localized in the entopeduncular nucleus were also found to facilitate GABA release. However, results obtained from in vivo microdialysis, in vivo electrochemistry, immunohistochemistry and confocal laser microscopy suggested that entopeduncular D-1 receptors could only be activated under pharmacological conditions. Adenosine A(1) receptors were found to antagonistically modulate the D-1-mediated regulation of the strioentopeduncular pathway. Furthermore, using in situ hybridization D-1 and A(1) receptors were shown to be colocalized in medium-sized striatal neurons, These results show that the strioentopeduncular neuron is a main locus for adenosine-dopamine interactions in the brain.