内源性硫化氢对慢性应激结肠高动力的影响

Actions of endogenous hydrogen sulfide on colonic hypermotility in a rat model of chronic stress

本文旨在探讨内源性硫化氢(hydrogen sulfide,H2S)与慢性应激大鼠结肠高动力的关系。大鼠随机分为慢性避水应激(water avoidance stress,WAS)组和假避水应激(sham water avoidance stress,SWAS)组,记录大鼠每日1 h应激期间大便粒数,连续10 d;分别制作结肠平滑肌条,使用生物机能实验系统记录两组肌条自发性收缩活性以及SWAS组H2S合成酶抑制剂预处理后收缩活性;测定结肠内源性H2S的产生浓度;采用免疫组化和Western blot等方法观察结肠内源性H2S合成酶分布及表达。结果显示,WAS组大鼠应激期间大便粒数、结肠肌条收缩的曲线下面积(area under the curve,AUC)均高于SWAS组(P<0.05);WAS组结肠内源性H2S产生量明显低于SWAS组(P<0.001);H2S合成酶胱硫醚-γ-裂解酶(cystathionine-γ-lyase,CSE)在纵行肌条和环形肌条细胞浆、肌间神经元细胞核中强表达,胱硫醚-β-合成酶(cystathionine-β-synthase,CBS)主要表达于肌间神经元胞浆;与SWAS组相比,WAS组大鼠结肠(去除粘膜及粘膜下层后)CBS和CSE的表达下调(P<0.001);H2S合成酶抑制剂明显增加SWAS组肌条收缩的AUC(P<0.001)。以上结果表明,内源性H2S合成酶表达下调、H2S合成减少是慢性应激结肠高动力的原因之一。

The present study was designed to investigate the potential role of endogenous hydrogen sulfide （HES） in chronic stress- induced colonic hypermotility. Male Wistar rats were submitted daily to 1 h of water avoidance stress （WAS） or sham WAS （SWAS） for l0 consecutive days. The total number of fecal pellets was counted at the end of each 1 h of WAS or SWAS session. Organ bath recordings were used to test the colonic motility. H2S production of colon was determined, and immunohistochemistry and Western blot were performed on rat colonic samples to detect the distribution and expression of HES-producing enzymes. The results showed that i） repeated WAS increased the number of fecal pellets per hour and the area under the curve （AUC） of the spontaneous contractions of colonic strips （P 〈 0.05）, ii） repeated WAS decreased the endogenous production of H2S and the expression of H2S-producing enzymes in the colon devoid ofmucosa and submuc0sa （P 〈 0.001）, iii） cystathionine-y-lyase （CSE） was strongly expressed in the cytosols of the circular and longitudinal smooth muscle cells and the nucleus of the myenteric plexus neurons, iv） cystathionine-β-synthase （CBS） was primarily localized in the cytosols of myenteric plexus neurons and weakly localized in the epithelial cells and v） inhibitors of HES-producing enzymes increased the contractile activity of colonic strips in the SWAS rats （P 〈 0.001）. In conclusion, the results suggest that the colonic hypermotility induced by repeated WAS may be associated with the decreased production of endogenous H2S.