title: Visceral sensation and irritable bowel syndrome; with special reference to comparison with functional abdominal pain syndrome.
abstract: OBJECTIVE
  Stress-induced visceral hypersensitivity may play an important role in the pathogenesis of irritable bowel syndrome (IBS) but not in functional abdominal pain syndrome (FAPS). We examined rectal sensation in those patients.
  
  
  METHODS
  Experiment 1: Rectal thresholds of pain (PT) and maximum tolerance were assessed by barostat with ramp distention before and after repetitive rectal painful distention (RRD). Experiment 2, PT was measured in basal state and after intravenous CRF (100 µg) or vehicle, together with or without RRD. Experiment 3: Three phasic distentions at physiological range were randomly loaded. The subjects were asked to mark the visual analogue scale (VAS) in reference to subjective intensity of sensation.
  
  
  RESULTS
  Experiment 1: Majority of IBS patients showed rectal hypersensitivity before RRD in contrast to FAPS. All IBS patients developed hypersensitivity after RRD, however, none of the FAPS patients did. RRD significantly reduced both thresholds in IBS (n=7) but did not change in controls (n=14) and FAPS (n=6). Experiment 2: PT was not modified by RRD in placebo group (n=6), while it was significantly reduced in CRF-treated group (n=5). On the other hand, CRF (n=5) or vehicle (n=5) without RRD did not alter PT. Experiment 3: The VAS ratings were increased in IBS (n=7) but significantly decreased in FAPS (n=6) as compared to controls (n=14).
  
  
  CONCLUSIONS
  RRD-induced rectal hypersensitivity seems to be reliable marker for IBS, and CRF may contribute to this response. FAPS patients may have hyposensitivity to non-noxious physiological distention, suggesting FAPS has different pathogenesis from IBS.
authors: Department of Regional Medicine and Education, Asahikawa Medical College, Asahikawa, Japan. tnozu@sea.plala.or.jp
authors: Tsukasa
authors: T
authors: Nozu
authors: Toshikatsu
authors: T
authors: Okumura
mesh_terms: D015746:Abdominal Pain / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D000328:Adult; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage; D004311:Double-Blind Method; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology; D007275:Injections, Intravenous; D043183:Irritable Bowel Syndrome / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D007564:Japan; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D011312:Pressure; D012007:Rectum / Q000294:innervation*; D055815:Young Adult
chemical_list: D003346:Corticotropin-Releasing Hormone