title: Cerebrospinal fluid kynurenic acid in male patients with schizophrenia - correlation with monoamine metabolites.
abstract: BACKGROUND
  The tryptophan metabolite kynurenic acid (KYNA) is an endogenous glutamate/nicotinic receptor antagonist. Previous studies have shown that the concentration of the compound is increased in cerebrospinal fluid (CSF) of patients with schizophrenia. Furthermore, it has been found that the CSF concentration of KYNA is positively correlated to CSF concentrations of the monoamine metabolites homovanillic acid (HVA) and 5-hydroxy indoleacetic acid (5-HIAA) in healthy control subjects.
  
  
  OBJECTIVE
  To study the correlations between KYNA and the monoamine metabolites HVA, 5-HIAA and 4-hydroxy-3-methoxyphenylglycol (HMPG) in CSF of male patients (n= 53, ranging from 20 to 48 years of age) with verified schizophrenia.
  
  
  METHODS
  CSF was obtained by lumbar puncture, and KYNA analysis was performed with an isocratic reversed-phase high-performance liquid chromatography system connected to a fluorescence detector. HVA, 5-HIAA and HMPG concentrations were measured by mass fragmentography with deuterium-labelled internal standards.
  
  
  RESULTS
  Positive intercorrelations were found between CSF KYNA, HVA and 5-HIAA, while CSF content of HMPG did not correlate to KYNA or any of the monoamine metabolites in CSF.
  
  
  CONCLUSIONS
  The results of this study suggest that increased KYNA formation is associated with an increased dopamine and serotonin turnover in male patients with schizophrenia.
authors.affiliation: 1Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Linda K
authors.initials: LK
authors.lastname: Nilsson-Todd
authors.affiliation: 2Department of Neuroscience and Locomotion, Psychiatry Section, Linköpings Universitet, Linköping, Sweden.
authors.forename: Conny
authors.initials: C
authors.lastname: Nordin
authors.affiliation: 3Department of Clinical Neuroscience, Psychiatry Section, HUBIN Project, Karolinska Institutet and Hospital, Stockholm, Sweden.
authors.forename: Erik G
authors.initials: EG
authors.lastname: Jönsson
authors.affiliation: 2Department of Neuroscience and Locomotion, Psychiatry Section, Linköpings Universitet, Linköping, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Skogh
authors.affiliation: 1Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sophie
authors.initials: S
authors.lastname: Erhardt