Release-regulating D-2 dopamine receptors are located on striatal glutamatergic nerve terminals.
The effects of dopamine (DA) and other dopaminergic receptor agonists on the depolarization-evoked release of endogenous glutamic acid (GLU) have been studied using synaptosomes prepared from rat corpus striatum and depolarized in superfusion with 15 mM KCl. DA and the selective D-2 receptor agonists quinpirole (LY-171555, the levorotatory enantiomer of LY-141865) and pergolide inhibited GLU release in a concentration-dependent way. The natural agonist was particularly effective causing 50% inhibition of GLU release at 10 nM. In contrast, the selective D-1 receptor agonist SK&F 38393 did not affect the release of GLU. The inhibitory effect of DA on the K+-evoked release of GLU was antagonized in a concentration-dependent manner by the selective D-2 receptor antagonist S-sulpiride, but not by the R-enantiomer. The data represent a direct demonstration that receptors sensitive to nanomolar concentrations of DA and belonging to the D-2 type are located on GLU axon terminals in the rat corpus striatum where they may modulate the release of GLU from glutamatergic afferents including the cortico-striatal pathway.
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D003342:Corpus Striatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004873:Ergolines / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005971:Glutamates / Q000493:pharmacokinetics*; D018698:Glutamic Acid; D008297:Male; D010479:Pergolide / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism*; D013237:Stereoisomerism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D001552:Benzazepines; D004873:Ergolines; D005971:Glutamates; D011954:Receptors, Dopamine; D019257:Quinpirole; D010479:Pergolide; D018698:Glutamic Acid; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D011188:Potassium