肾上腺髓质素对小鼠肠缺血再灌注损伤的保护作用

Effect of adrenomedullin on intestinal ischemia/reperfusion injury in mouse

目的探讨肾上腺髓质素（AM）在肠缺血再灌注损伤（I／R）中对肠黏膜屏障功能的影响及机制。方法将21只C57小鼠随机分为3组：（1）Sham组；（2）I／R组；（3）I／R＋AM组。采用夹闭肠系膜L动脉30min、再灌注6h作为制备肠缺血再灌注损伤模型的方法。用苏木素-伊红（HE）染色的方法观察肠黏膜的损伤；测定小肠肠黏膜的跨上皮电阻（TER）；检测紧密连接蛋nZO-1和Claudin-1蛋白水平的变化以及信号分子727位丝氨酸磷酸化的信号转导与转录激活子1[p-STAT1（S727）]在各组中的激活。结果HE染色结果显示肠I／R引起部分小肠绒毛上皮脱落，经AM预处理使得小肠绒毛重新排列整齐，显著缓解肠I／R所致的形态结构破坏。肠I／R引起ZO-1和Claudin-1的蛋白表达水平较Sham组分别下降38．54％及42．98％，并引起TER降低44．57％；经AM预处理使得ZO-1和Claudin—1的蛋白的表达较I／R组显著升高（分别为31．33％、33．92％），同时TER值较肠I／R组升高25．97％，并且使得肠I／R所致的p-STAT1（S727）激活被显著抑制（较I／R组降低56．52％）。结论AM对小鼠肠I／R损伤后肠黏膜屏障具有较好的保护作用，并且可以调控肠道紧密连接蛋白的表达，进而影响肠道通透性的改变，其机制可能与抑制p-STAT1（S727）的激活有关。

Objective To investigate the effect of adrenomedullin on intestinal mucosal barrier function in a mouse model of intestinal ischemia/repeffusion Methods Twenty-one C57BL/6 mice were randomly divided into Sham group, ischemia/repeffusion （I/R） group and I/R ＋ AM group, the superior lnesenteric artery （SMA） was occluded for 30 min using nontraumatic vascular clamps, followed by reperthsion tbr 6 h. Then sections were obtained for hematoxylin-eosin （HE） staining, to observe the morpho- logical changes of intestinal mucosa. Ussing chambers was used to detection of intestinal permeability （TER）. The protein expressions of tight junction proteins （ZO-1 and Claudin-1 ） were examined by using Western blotting, the activation of p-STAT1 （$727） was also assayed. Results HE staining showed intesfinal I/R caused part of villus epithelial shedding, after AM pretreatment the villus in the small intestine rearranged in neat rows, attenuated the disruption of intestinal morphological structure caused by intestinal I/R. The protein expressions of ZO-1 and Claudin-I in I/R group were significantly decreased by 38.54% and 42. 98% respectively when compared with that in Sham group （P 〈 0. 01 ）. The TER value in I/R group was decreased by 44.57% as compared with Sham group （P 〈 0. 05 ） After AM pretreatment, the protein expression of ZO-1 and Claudin-1 protein expression were significantly raised compared to that in I/R group （ by 31.33% , 33.92% ）. Sinmltaneously, TER in I/R ＋ AM group was significantly raised as compare with I/R group by 25.97%. And Intestinal I/R induced p-STAT1 （$727） activation was signifi- cantly inhibited. （ decreased as compared with I/R group by 56. 52% ） Conclusion AM can attenuate intestinal mucosal barrier dysfunction by regulating the expression of intestinal tight junction proteins. The inhibition of p-STATI （$727） activation may be involved in this mechanism.