title: Differentiation between the stimulus effects of l-5-hydroxytryptophan and LSD.
abstract: The stimulus properties of the serotonin precursor 1-5-hydroxytryptophan (5-HTP) and the hallucinogen d-lysergic acid diethylamide (LSD) were compared in a two-lever, water-reinforced drug discrimination task. 5-HTP (in combination with the peripheral decarboxylase inhibitor Ro 4-4602) elicited no more than 50% drug-lever responding in rats trained to discriminate LSD (0.08 mg/kg) from saline while LSD substituted completely in animals trained to discriminate 5-HTP (50 mg/kg) from saline. Combination tests indicated that, while the 5-HTP cue was unaffected by pretreatment with various serotonin antagonists, the substitution of LSD for 5-HTP was abolished by the putative serotonin-2 antagonist ketanserin. It was concluded that LSD mimics 5-HTP by stimulating a subset of serotonin receptors activated by 5-HTP which are sensitive to ketanserin (serotonin-2?).
authors.forename: K A
authors.initials: KA
authors.lastname: Cunningham
authors.forename: P M
authors.initials: PM
authors.lastname: Callahan
authors.forename: J B
authors.initials: JB
authors.lastname: Appel
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000818:Animals; D001545:Benserazide / Q000494:pharmacology; D003463:Cues; D004192:Discrimination, Psychological / Q000187:drug effects*; D007650:Ketanserin; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology*; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D010880:Piperidines; D011814:Quipazine; D001545:Benserazide; D008238:Lysergic Acid Diethylamide; D007650:Ketanserin; D006916:5-Hydroxytryptophan