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Exogenous interleukin-6 facilitated the contraction of the colon in a depression rat model
Li Zhang1, Liudan Hu, Mingkai Chen
1Department of Gastroenterology, Renmin Hospital of Wuhan University, Number 238, Jiefang Road, Wuhan, 430060, Hubei Province, China. zhangt0712@126.com
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.
Aims:
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.

