A comparison of the discriminative stimulus properties of l-5-hydroxytryptophan in the presence of either citalopram or Ro 4-4602.
The establishment of stimulus control by 5-HTP, the amino acid precursor for serotonin (5-HT), has been reported previously [1-3]. In the present investigation, two groups of rats were trained with 5-HTP versus saline in a 2-lever discrimination procedure. Prior to the administration of 5-HTP, subjects were pretreated with either Ro 4-4602, an inhibitor of peripheral decarboxylase (R-HTP), or citalopram, a specific 5-HT reuptake inhibitor (C-HTP). Neither C-HTP nor R-HTP was antagonized completely by either pirenperone or pizotyline. When C-HTP and R-HTP were tested in a third group of rats trained with LSD, complete generalization was not observed. The results of cross tests in the R-HTP and C-HTP groups with LSD, TFMPP, 8-OH-DPAT, C-HTP, and R-HTP indicate that the stimuli induced by R-HTP and C-HTP are similar but not identical. Taken together, these data suggest that 5-HTP produces a compound stimulus that is not readily explained in terms of either 5-HT1 or 5-HT2 receptors alone.
Winter
J C
JC
Department of Pharmacology and Therapeutics, School of Medicine, State University of New York, Buffalo 14214.
Rabin
R A
RA
D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000818:Animals; D001545:Benserazide / Q000494:pharmacology*; D015283:Citalopram / Q000494:pharmacology*; D003216:Conditioning, Operant; D004192:Discrimination, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006834:Hydrazines / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344
D006834:Hydrazines; D015283:Citalopram; D001545:Benserazide; D006916:5-Hydroxytryptophan