Effects of N,N-dimethyltryptamine on electrically evoked responses in the cat visual system and modification by neuroleptic agents.

The effects of N,N-dimethyltryptamine on electrically evoked potentials in the visual system of the cat and the interaction of selected neuroleptic agents with ~ethyi~yp~mine were studied. Dimethyltryptamine caused a doss-dependent decrease in the amplitude of the response evoked by stimulation of the optic chiasm as recorded in the lateral geniculate nucleus and the visual cortex. Dimethyltryptamine had no significant effect on antidromically evoked potentials in the lateral geniculate nucleus or potentials in the visual cortex produced by optic radiation stimulation. A dose-dependent biphasic effect was found in animals pretreated with various doses of chlorpromazine, haloperidol, thiothixene, molindone, methiothepin and octoclothepin. Methiothepin and octoclothepin were the most potent antagonists of dimethyltryptamine, while molindone was essentially ineffective. Low doses of the neuroieptics, with the exception of molindone, potentiated the inhibitory action of dimethyl~yptamine on evoked responses.