title: Locus ceruleus neurons in people with autism contain no histochemically-detectable mercury.
abstract: Exposure to environmental mercury has been proposed to play a part in autism. Mercury is selectively taken up by the human locus ceruleus, a region of the brain that has been implicated in autism. We therefore looked for the presence of mercury in the locus ceruleus of people who had autism, using the histochemical technique of autometallography which can detect nanogram amounts of mercury in tissues. In addition, we sought evidence of damage to locus ceruleus neurons in autism by immunostaining for hyperphosphorylated tau. No mercury was found in any neurons of the locus ceruleus of 6 individuals with autism (5 male, 1 female, age range 16-48 years). Mercury was present in locus ceruleus neurons in 7 of 11 (64%) age-matched control individuals who did not have autism, which is significantly more than in individuals with autism. No increase in numbers of locus ceruleus neurons containing hyperphosphorylated tau was detected in people with autism. In conclusion, most people with autism have not been exposed early in life to quantities of mercury large enough to be found later in adult locus ceruleus neurons. Human locus ceruleus neurons are sensitive indicators of mercury exposure, and mercury appears to remain in these neurons indefinitely, so these findings do not support the hypothesis that mercury neurotoxicity plays a role in autism.
authors.affiliation: Discipline of Pathology, The University of Sydney, Brain and Mind Centre, Camperdown, NSW, 2050, Australia. roger.pamphlett@sydney.edu.au.
authors.forename: Roger
authors.initials: R
authors.lastname: Pamphlett
authors.affiliation: Discipline of Pathology, The University of Sydney, Brain and Mind Centre, Camperdown, NSW, 2050, Australia. stephen.jew@sydney.edu.au.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kum Jew
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D008125:Locus Coeruleus / Q000187:drug effects* / Q000293:injuries / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000633:toxicity*; D008875:Middle Aged; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology
chemical_list: D008628:Mercury
keywords: Autism; Heavy metal; Locus ceruleus; Locus coeruleus; Mercury; Toxicant