title: Serotonergic disturbances in autistic disorder: L-5-hydroxytryptophan administration to autistic youngsters increases the blood concentrations of serotonin in patients but not in controls.
abstract: Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) may play a role in the pathophysiology of autistic disorder. This study examines the whole blood concentrations of 5-HT and 5-hydroxy-indoleacetic acid (5-HIAA) in baseline conditions and during a challenge with L-5-OH-tryptophane (5-HTP; 4 mg/kg in non enteric-coated tablets), the precursor of 5-HT, in a study group of 18 male, post-pubertal, Caucasian autistic patients (age 13-19 y.; I.Q.>55) and 20 matched healthy volunteers. In baseline conditions, no significant differences in 5-HT or 5-HIAA levels could be found between autistic youngsters and normal controls. 5-HTP administration significantly increased the levels of 5-HT in autistic youngsters but not in normal controls. Following 5-HTP challenge the 5-HT levels were significantly higher in autistic patients than in healthy volunteers. After challenge with 5-HTP, no significant differences were found in the concentrations of 5-HIAA or the test substance between autistic youngsters and normal controls. Differences in the peripheral metabolism of 5-HT which may not be observed in baseline conditions but which became clear after loading with 5-HTP, suggest that an increased synthesis of 5-HT from its precursor 5-HTP might be a one factor responsible for differences in the serotonergic system between autistic post-pubertal youngsters and normal controls.
authors.affiliation: The University Center of Child and Adolescent Psychiatry, A.Z.M., University of Antwerp, Wilrijk, Belgium. Jan.croonenberghs@ocmw.antwerpen.be
authors.forename: Jan
authors.initials: J
authors.lastname: Croonenberghs
authors.forename: Robert
authors.initials: R
authors.lastname: Verkerk
authors.forename: Simon
authors.initials: S
authors.lastname: Scharpe
authors.forename: Dirk
authors.initials: D
authors.lastname: Deboutte
authors.forename: Michael
authors.initials: M
authors.lastname: Maes
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000097:blood / Q000378:metabolism* / Q000523:psychology; D005260:Female; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012701:Serotonin / Q000097:blood / Q000378:metabolism*
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D006916:5-Hydroxytryptophan