Tryptamine-induced drug effects insensitive to serotoninergic antagonists: evidence of specific tryptaminergic receptor stimulation?
The drug effects of tryptamine and 5-hydroxytryptopham (5-HTP) in the rabbit were compared following monoamine oxidase inhibition and various drug pretreatments. Both agents evoked hyperthermia and behavioural excitation; tryptamine but not 5-HTP also produced forepaw clonic activity. Serotoninergic receptor blockers abolished the effects of 5-HTP but only weakly influenced tryptamine responses. Both tryptamine and 5-HTP effects were potentiated by fluoxetine. Methergoline, a putative tryptaminergic receptor blocker, antagonized tryptamine-induced hyperthermia and forepaw clonus but did not influence 5-HTP responses. It is postulated that while 5-HTP produces its effects through a serotoninergic mechanism, some of the responses to tryptamine result from activation of a specific tryptamine-sensitive mechanism.
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D008297:Male; D011817:Rabbits; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013268:Stimulation, Chemical; D013997:Time Factors; D014363:Tryptamines / Q000494:pharmacology*
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D014363:Tryptamines; D006916:5-Hydroxytryptophan