title: Exogenous interleukin-6 facilitated the contraction of the colon in a depression rat model.
abstract: BACKGROUND
  Gut dysmotility is closely associated with proinflammatory cytokines both in irritable bowel syndrome and inflammatory bowel disease. There is a dose-response relationship between depression and these inflammatory cytokines.
  
  
  OBJECTIVE
  In the present study, we aimed to investigate the effect of Interleukin-6 (IL-6) on colon motility in a rat model of depression induced by chronic unpredictable mild stress (CUMS).
  
  
  METHODS
  The contraction of the circular muscle strips of proximal colon was monitored by a polygraph. IL-6 and IL-6 receptor (IL-6R) mRNA was assayed by real-time quantitative PCR. Immunohistochemistry staining was used to locate the IL-6 and IL-6R in the rat colon.
  
  
  RESULTS
  IL-6 and IL-6R were expressed in the mucosal layer, smooth muscle cells, and myenteric plexus of the colon. Exogenous IL-6 (20 ng/ml) increased the contraction of the circular muscle strip. Pretreatment of tetrodotoxin (blocker of voltage-dependent Na(+) channel on nerve fiber) blocks the excitatory effect of IL-6 on the contraction of the colon in non-stressed rats, but partially inhibited IL-6-induced excitatory effect on the muscle strips in CUMS-treated rats.
  
  
  CONCLUSIONS
  These results suggest that IL-6-induced the contraction of the colonic strip by acting on the gut's nervous system and acting directly on the smooth muscle in rats with depression.
authors.affiliation: Department of Gastroenterology, Renmin Hospital of Wuhan University, Number 238, Jiefang Road, Wuhan, 430060, Hubei Province, China. zhangt0712@126.com
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Liudan
authors.initials: L
authors.lastname: Hu
authors.forename: Mingkai
authors.initials: M
authors.lastname: Chen
authors.forename: Baoping
authors.initials: B
authors.lastname: Yu
mesh_terms: D000818:Animals; D003106:Colon / Q000502:physiology*; D007375:Interleukin-1 / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019947:Receptors, Interleukin-6 / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D013395:Sucrose
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D019947:Receptors, Interleukin-6; D013395:Sucrose