The 5-hydroxytryptamine 5-HT1D receptor subtype is negatively coupled to adenylate cyclase in calf substantia nigra

Abstract

1) The possibility was explored that the recently defined 5-HT1D binding sites could be negatively coupled to adenylate cyclase in calf substantia nigra. 2) 5-HT inhibited forskolin-stimulated adenylate cyclase activity in a concentration-dependent manner (EC50 valu e = 24.0 nmol/l, Emax = 22.7% inhibition) in the presence of GTP (10 μmol/l), which was required for this inhibitory effect. 3) The following 5-HT receptor agonists inhibited adenylate cyclase activity (in decreasing order of potency): 5-carboxamidotryptamine > 5-HT > 5-methoxytryptamine > 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole (RU 24969) ≥ N1N-dipropyl-5-carboxamidotryptamine > 8-hydroxy-2(di-n-propylamino)-tetra..