title: Pituitary-adrenal response to naloxone in non-ulcer dyspepsia: preliminary evidence for a reduction in central opioid tone.
abstract: BACKGROUND
  Non-ulcer dyspepsia (NUD) is one of the core functional bowel disorders. There has been recent emphasis on possible abnormal brain-gut interactions as being central to its pathophysiology. In this preliminary study, we examined central opioid tone in Helicobacter pylori-negative NUD patients using naloxone, an opioid antagonist, which stimulates pituitary-adrenal activity. The opioid system is known to govern nociceptive processing and to play a role in gut motor activity.
  
  
  METHODS
  Eight subjects with NUD and 8 age- and sex-matched healthy subjects were examined.
  
  
  METHODS
  Naloxone, 0.125 mg/kg, was administered at time 0. Adrenocorticotropin (ACTH) and cortisol responses were measured over a 120-min period. Maximum pituitary-adrenal responses in the 2 groups were compared.
  
  
  RESULTS
  The ACTH response was significantly attenuated in the NUD group (p < 0.05). The cortisol response did not differ between the 2 groups (p = 0.7).
  
  
  CONCLUSIONS
  Central opioid tone may be reduced in subjects with NUD. Our preliminary findings suggest that altered opioidergic activity may contribute to NUD pathophysiology, influencing the symptom profile through altered gut motor activity or possibly by influencing visceral sensitivity.
authors.affiliation: Department of Psychiatry, Cork University, Wilton, Cork, Ireland. lucinda@gofree.indigo.ie
authors.forename: Lucinda V
authors.initials: LV
authors.lastname: Scott
authors.forename: Omar
authors.initials: O
authors.lastname: Rathore
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Dinan
authors.forename: P W N
authors.initials: PW
authors.lastname: Keeling
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000096:biosynthesis; D000328:Adult; D016022:Case-Control Studies; D004415:Dyspepsia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000096:biosynthesis; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000502:physiology
chemical_list: D009292:Narcotic Antagonists; D009270:Naloxone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone