title: Increased serotonin axons (immunoreactive to 5-HT transporter) in postmortem brains from young autism donors.
abstract: Imaging studies of serotonin transporter binding or tryptophan retention in autistic patients suggest that the brain serotonin system is decreased. However, treatment with drugs which increase serotonin (5-HT) levels, specific serotonin reuptake inhibitors (SSRIs), commonly produce a worsening of the symptoms. In this study we examined 5-HT axons that were immunoreactive to a serotonin transporter (5-HTT) antibody in a number of postmortem brains from autistic patients and controls with no known diagnosis who ranged in age from 2 to 29 years. Fine, highly branched, and thick straight fibers were found in forebrain pathways (e.g. medial forebrain bundle, stria terminalis and ansa lenticularis). Many immunoreactive varicose fine fibers were seen in target areas (e.g. globus pallidus, amygdala and temporal cortex). Morphometric analysis of the stained axons at all ages studied indicated that the number of serotonin axons was increased in both pathways and terminal regions in cortex from autism donors. Our findings provide morphological evidence to warrant caution when using serotonin enhancing drugs (e.g. SSRIs and receptor agonist) to treat autistic children. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.
authors.affiliation: Dept. of Biology, New York University, 100 Washington Sq East, New York, NY 11791, USA. eca1@nyu.edu
authors.forename: Efrain C
authors.initials: EC
authors.lastname: Azmitia
authors.forename: Jorawer S
authors.initials: JS
authors.lastname: Singh
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Whitaker-Azmitia
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000378:metabolism*; D001344:Autopsy; D001369:Axons / Q000378:metabolism*; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005917:Globus Pallidus / Q000502:physiology; D006801:Humans; D008297:Male; D008474:Medial Forebrain Bundle / Q000502:physiology; D009412:Nerve Fibers / Q000502:physiology; D016548:Prosencephalon / Q000502:physiology; D012701:Serotonin / Q000276:immunology / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000276:immunology / Q000378:metabolism*; D020530:Subthalamus / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology; D055815:Young Adult
chemical_list: C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin