Li Zhang1, Liudan Hu, Mingkai Chen, Baoping Yu. 1. Department of Gastroenterology, Renmin Hospital of Wuhan University, Number 238, Jiefang Road, Wuhan, 430060, Hubei Province, China. zhangt0712@126.com
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. 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.
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.