5-HT1D-LIKE RECEPTORS INHIBIT THE RELEASE OF ENDOGENOUSLY FORMED [H-3] GABA IN HUMAN, BUT NOT IN RABBIT, NEOCORTEX

Both human and rabbit brain contain the 5-hydroxytryptamine (5-HT)(1D) subtype of 5-HT1 receptors, We studied the effects of 5-HT1D receptor stimulation on neocortical [H-3]gamma-aminobutyric acid (GABA) releas e from GABAergic neurons in these species. The 5-HT1D receptor agonist sumatriptan depressed [H-3]GABA release in human neocortex and the 5- HT1 receptor antagonist metitepin prevented this depression with poten cies suggesting mediation by 5-HT1D-like receptors. In rabbit neocorte x, however, 5-HT1D agonists did not affect the release of [H-3]GABA. S ince 5-HT and GABA seem to function antagonistically in anxiety disord ers their neocortical interaction may be (patho)physiologically releva nt.