WAY-100635 AND GR127935 - EFFECTS ON 5-HYDROXYTRYPTAMINE-CONTAINING NEURONS

zinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (W AY-100635) is a potent and selective 5-HT1A receptor antagonist in a s lice preparation of the guinea pig dorsal raphe nucleus: the inhibitor y actions on 5-HT neuronal firing of 5-hydroxytryptamine (5-HT, seroto nin), 5-carboxamidotryptamine (5-CT) and 8-hydroxy-2-(di-n-propylamino )tetralin (8-OH-DPAT), but not those of baclofen, were abolished by 30 nM WAY-100635. The selective 5-HT1D receptor antagonist enyl]-2'-meth yl-4'-(5-methyl-1,2,4-oxadiazol-3-yl) [1,1-biphenyl]-4- carboxamide (G R127935, 300 nM) did not attenuate the 5-HT induced inhibition, indica ting that 5-HT1D receptors do not contribute to the inhibitory action of exogenous 5-HT on 5-HT neurones.