title: Human plasma glutathione peroxidase and symptom severity in schizophrenia.
abstract: BACKGROUND
  Previous studies have shown impaired antioxidant defense system in schizophrenia, including alterations in glutathione peroxidase (GSH-Px) activity in erythrocytes. There exists a related enzyme, human plasma GSH-Px (hpGSH-Px), that has not been previously examined in schizophrenia.
  
  
  METHODS
  An enzyme-linked immunoassay was used to determine hpGSH-Px levels in male schizophrenic patients (n = 39), using a within-subject, on-off haloperidol (HD) treatment design, compared with age- and gender-matched normal control subjects (n = 37).
  
  
  RESULTS
  hpGSH-Px was not significantly different between normal control subjects and patients, consistent with our previous findings in erythrocyte GSH-Px. There were no significant treatment effects. hpGSH-Px was significantly and positively correlated with psychosis rating scores in patients both on and off HD treatment.
  
  
  CONCLUSIONS
  Although not different from normal controls, hpGSH-Px levels in patients may reflect oxidative stress associated with greater psychosis severity. The present findings thus suggest that schizophrenic patients, without obvious increase of endogenous antioxidant enzymes (e.g., hpGSH-Px), may be at risk for oxidative damage.
authors.affiliation: VA Pittsburgh Healthcare System, Pennsylvania 15206, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Yao
authors.forename: R D
authors.initials: RD
authors.lastname: Reddy
authors.forename: D P
authors.initials: DP
authors.lastname: van Kammen
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D005979:Glutathione Peroxidase / Q000097:blood* / Q000187:drug effects; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000188:drug therapy / Q000201:enzymology*; D012720:Severity of Illness Index
chemical_list: D014150:Antipsychotic Agents; D015415:Biomarkers; D005979:Glutathione Peroxidase; D006220:Haloperidol