Synergism between D1 and D2 dopamine receptors in the inhibition of the evoked release of [3H]GABA in the rat prefrontal cortex.
In order to examine a possible interaction between D1 and D2 receptors in the dopaminergic control of the electrically-evoked release of [3H]GABA in the rat prefrontal cortex, the effects of D1 and D2 dopamine agonists were studied in vitro on cortical slices. The D1 agonist SKF38393 (10(-5) M) inhibited the electrically-evoked release of [3H]GABA. This effect was totally reversed by both the D1 antagonist SCH23390 (10(-7) M) and the D2 antagonist sulpiride (10(-5) M). We previously observed that maximal D2-mediated inhibition of the electrically-evoked release of [3H]GABA was obtained with 10(-7) M RU24926 and 10(-8) M LY171555. Here we showed that the inhibition produced by these two D2 agonists is also abolished by 10(-7) M SCH23390. In dopamine-depleted slices from reserpine-treated animals, it was not possible to detect an effect of either RU24926 (10(-7) M) or SKF38393 (10(-5) M), suggesting a permissive role of endogenous dopamine in the effect of either D2 or D1 agonist. Finally, SKF38393 used at a subliminar concentration (10(-6) M) was able to potentiate the effect of a liminar concentration of RU24926 (1.5 x 10(-8) M). Taken together these results strongly suggest that in the rat prefrontal cortex a D1-D2 receptor synergism is involved in the dopaminergic control of the electrically-evoked release of [3H]GABA.
Retaux
S
S
Laboratoire de Neurochimie-Anatomie, Université Pierre & Marie Curie, Paris, France.
Besson
M J
MJ
Penit-Soria
J
J
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D004558:Electric Stimulation; D005625:Frontal Lobe / Q000378:metabolism*; D018756:GABA Antagonists; D008297:Male; D010627:Phenethylamines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012110:Reserpine / Q000494:pharmacology; D014316:Tritium
D001552:Benzazepines; D018756:GABA Antagonists; D010627:Phenethylamines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D014316:Tritium; C025254:RU 24926; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D012110:Reserpine