title: Effects of oral 5-hydroxytryptophan on a standardized planning task: insight into possible dopamine/serotonin interactions in the forebrain.
abstract: OBJECTIVE
  Several studies have suggested that exogenous administration of the serotonin precursor 5-hydroxytryptophan (5-HTP) can result in the ectopic production of serotonin in dopaminergic neurons and a concomitant reduction in dopamine release. This study tested this hypothesis using the Tower of London (TOL), a test of planning and executive control that is sensitive to changes in forebrain dopamine activity, but insensitive to alterations in serotonin.
  
  
  METHODS
  A sample of 68 undergraduates participated, and each received either three 50-mg 5-HTP capsules or placebos, and completed the TOL following a set absorption period.
  
  
  RESULTS
  5-HTP significantly lengthened the average time needed to complete each of the 10 trials of the TOL. 5-HTP did not affect accuracy on this task.
  
  
  CONCLUSIONS
  Oral exogenous 5-HTP disrupts dopaminergic function in the human forebrain.
authors.affiliation: Department of Psychology, Elon University, Elon, NC 27244, USA. mgendle@elon.edu
authors.forename: Mathew H
authors.initials: MH
authors.lastname: Gendle
authors.forename: Erica L
authors.initials: EL
authors.lastname: Young
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Romano
mesh_terms: D006916:5-Hydroxytryptophan / Q000008:administration & dosage / Q000494:pharmacology*; D000284:Administration, Oral; D000293:Adolescent; D018687:Antidepressive Agents, Second-Generation / Q000008:administration & dosage / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D004311:Double-Blind Method; D056344:Executive Function / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors; D055815:Young Adult
chemical_list: D018687:Antidepressive Agents, Second-Generation; D012701:Serotonin; D006916:5-Hydroxytryptophan; D004298:Dopamine