title: [Imbalance of plasma amino acids in patients with autism and subjects with attention deficit/hyperactivity disorder].
abstract: BACKGROUND
  Plasma and brain amino acids are influenced by dietary intake. Alterations of plasma amino acid concentrations have been reported in neuropsychiatric disorders.
  
  
  OBJECTIVE
  To analyse the plasma amino acid values in subject diagnosed with autism, with attention deficit/hyperactivity disorder (ADHD), and healthy subjects as controls.
  
  
  METHODS
  Forty subjects affected by autism, 11 with ADHD and 41 healthy subjects (age range 3 18 years old) were included in this study. Peripheral venous blood was obtained in fasting condition, collected in EDTA tubes and centrifuged. Plasma was de proteinised with sulfosalicylic acid. Amino acids were analysed by ion exchange liquid chromatography with an LKB amino acid analyser with sodium citrate elution system and ninhydrin reaction. Results were expressed as mmol/L.
  
  
  CONCLUSIONS
  In both disorders a diminution of phenylalanine and glutamine plasma concentrations was observed beside an increase of glycine. Lysine appeared increased only in autistic subjects. These alterations produce an imbalance with the rest of plasma amino acids competing at the brain blood barrier by the same transport system thus causing alterations in the metabolism and/or transport of amino acids to the brain, altering CNS functions. The phenylalanine decreasing, beside glycine increasing appear to support the hypothesis of a disorder in the inhibitory neurotransmission system, especially in ADHD. The diminution of phenylalanine and the increasing of lysine in autism are suggestive that these two amino acids are metabolically related.
authors.affiliation: Instituto de Investigaciones Biológicas, Facultad de Medicina, Universidad del Zulia. Maracaibo, Zulia, Venezuela. zavalam@iamnet.com
authors.forename: M
authors.initials: M
authors.lastname: Zavala
authors.forename: H V
authors.initials: HV
authors.lastname: Castejón
authors.forename: P A
authors.initials: PA
authors.lastname: Ortega
authors.forename: O J
authors.initials: OJ
authors.lastname: Castejón
authors.forename: A
authors.initials: A
authors.lastname: Marcano de Hidalgo
authors.forename: N
authors.initials: N
authors.lastname: Montiel
mesh_terms: D000293:Adolescent; D000596:Amino Acids / Q000378:metabolism*; D001289:Attention Deficit Disorder with Hyperactivity / Q000378:metabolism*; D001321:Autistic Disorder / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D008297:Male
chemical_list: D000596:Amino Acids