title: Reduced plasma apelin levels in patients with autistic spectrum disorder.
abstract: BACKGROUND
  Dysregulation of the vasopressin (AVP) system has been implicated in the pathogenesis of autistic spectrum disorder (ASD). Apelin is a recently discovered neuropeptide that could counteract AVP actions and whose receptors are colocalized with vasopressin in hypothalamic magnocellular neurons. Aims of the present study were to investigate circulating levels of apelin in patients with ASD and to assess their correlation with plasma AVP concentrations.
  
  
  METHODS
  Plasma levels of apelin and AVP were measured in a total of 18 patients with ASD and 21 age- and gender-matched healthy comparison subjects. The Childhood Autism Rating Scale (CARS) was used to assess the severity of autistic symptoms.
  
  
  RESULTS
  Significantly reduced levels of apelin (p < 0.001) and elevated concentrations of AVP (p = 0.02) were found in ASD patients as compared to controls. Additionally, a significant inverse correlation between apelin and AVP levels was found within the ASD group (r = -0.61; p = 0.007), but not in healthy participants (r = -0.26; p = 0.25). Multivariate linear regression analysis showed that only AVP concentrations independently predicted apelin values in ASD individuals (beta = -0.42, t = 2.63, p = 0.014). No correlation was seen between apelin levels and CARS scores (r = -0.10; p = 0.68).
  
  
  CONCLUSIONS
  Our findings of a significantly reduced peripheral level of apelin coupled with elevated AVP point to a subtle but definite vasopressinergic dysfunction in autism that could play a role in the etiopathophysiology of this disorder in humans.
authors.affiliation: Department of Health Sciences, Section of Psychiatry, University of Pavia, Pavia, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Boso
authors.forename: Enzo
authors.initials: E
authors.lastname: Emanuele
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Politi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pace
authors.forename: Mariarosa
authors.initials: M
authors.lastname: Arra
authors.forename: Stefania
authors.initials: S
authors.lastname: Ucelli di Nemi
authors.forename: Francesco
authors.initials: F
authors.lastname: Barale
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000097:blood / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008297:Male; D014667:Vasopressins / Q000097:blood
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; C495199:apelin-13 peptide; D014667:Vasopressins