title: Lipopolysaccharide induces visceral hypersensitivity: role of interleukin-1, interleukin-6, and peripheral corticotropin-releasing factor in rats.
abstract: BACKGROUND
  Lipopolysaccharide (LPS) induces visceral hypersensitivity, and corticotropin-releasing factor (CRF) also modulates visceral sensation. Besides, LPS increases CRF immunoreactivity in rat colon, which raises the possibility of the existence of a link between LPS and the CRF system in modulating visceral sensation. The present study tried to clarify this possibility.
  
  
  METHODS
  Visceral sensation was assessed by abdominal muscle contractions induced by colonic balloon distention, i.e., visceromotor response, electrophysiologically in conscious rats. The threshold of visceromotor response was measured before and after administration of drugs.
  
  
  RESULTS
  LPS at a dose of 1 mg/kg subcutaneously (sc) decreased the threshold at 3 h after the administration. Intraperitoneal (ip) administration of anakinra (20 mg/kg), an interleukin-1 (IL-1) receptor antagonist, or interleukin-6 (IL-6) antibody (16.6 µg/kg) blocked this effect. Additionally, IL-1β (10 µg/kg, sc) or IL-6 (10 µg/kg, sc) induced visceral allodynia. Astressin (200 µg/kg, ip), a non-selective CRF receptor antagonist, abolished the effect of LPS, but astressin2-B (200 µg/kg, ip), a CRF receptor type 2 (CRF2) antagonist, did not alter it. Peripheral CRF receptor type 1 (CRF1) stimulation by cortagine (60 µg/kg, ip) exaggerated the effect of LPS, but activation of CRF2 by urocortin 2 (60 µg/kg, ip) abolished it.
  
  
  CONCLUSIONS
  LPS induced visceral allodynia possibly through stimulating IL-1 and IL-6 release. In addition, this effect was mediated through peripheral CRF signaling. Since the LPS-cytokine system is thought to contribute to altered visceral sensation in the patients with irritable bowel syndrome, these results may further suggest that CRF plays a crucial role in the pathophysiology of this disease.
authors.affiliation: Department of Regional Medicine and Education, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa, 078-8510, Japan. tnozu@sea.plala.or.jp.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Nozu
authors.affiliation: Department of General Medicine, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa, 078-8510, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Miyagishi
authors.affiliation: Department of Regional Medicine and Education, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa, 078-8510, Japan.
authors.forename: Rintaro
authors.initials: R
authors.lastname: Nozu
authors.affiliation: Research Center for Brain Function and Medical Engineering, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa, 078-8510, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takakusaki
authors.affiliation: Department of General Medicine, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa, 078-8510, Japan.
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Okumura
mesh_terms: D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D004195:Disease Models, Animal; D007375:Interleukin-1 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D043183:Irritable Bowel Syndrome / Q000503:physiopathology; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D015398:Signal Transduction; D013312:Stress, Physiological; D059265:Visceral Pain / Q000503:physiopathology*; D000099052:CRF Receptor, Type 1
chemical_list: C101531:CRF receptor type 2; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D018019:Receptors, Corticotropin-Releasing Hormone; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone
keywords: CRF; IL-1; IL-6; LPS; Visceral allodynia