应激状态下大鼠胃黏膜组织中内皮素-1A受体mRNA的表达及其意义

Expression of Endothelin-lA Receptor mRNA in Gastric Mucosa of Stressed Rats

应激性溃疡(SU)是危重疾病的常见严重并发症,其发生机制尚不清楚。研究表明内源性缩血管因子内皮素(ET)-1与SU密切相关,而关于其受体表达在SU发生中作用的研究尚少。目的:探讨ET-1A受体(ETAR)mRNA表达在SU发生中的作用和意义。方法:以冷束缚应激(CRS)制备大鼠胃溃疡模型,应激前和应激1 h、3 h、6 h、9 h、12 h后分别采用放射免疫测定、逆转录聚合酶链反应(RT-PCR)和斑点杂交等方法,动态检测血浆和胃黏膜组织中的ET-1和胃黏膜组织中的ETAR mRNA水平,同时检测胃黏膜血流量(GMBF)和溃疡指数(UI)等指标的变化情况。结果:与正常对照组相比,各应激组大鼠血浆和胃黏膜组织中的ET-1水平均显著升高(P<0.05),GMBF显著下降(P<0.01),UI显著增加(P<0.01);胃黏膜组织中的ET-1水平与UI呈显著正相关(r=0.98,P<0.01),与GMBF呈显著负相关(r=-0.89,P<0.05),而血浆ET-1水平与GMBF、UI相关性不显著(r=-0.61,0.43,P>0.05)。GMBF与UI呈显著负相关(r=-0.98,P<0.01)。RT-PCR和斑点杂交显示各应激组大鼠胃黏膜组织中ETAR mRNA的表达水平较正常对照组显著升高(P<0.01),并与胃黏膜组织中的ET-1水平和UI呈显著正相关(r=0.93,0.95,P<0.01)。结论:在CRS诱发大鼠急性胃黏膜损伤的过程中,胃黏膜组织可显著增加ET-1的合成分泌和ETAR

Background: Stress ulcer (SU) is a serious complication of critical diseases, but the pathogenesis of SU remains unclarified. It is reported that there is close relationship between SU and endothelin (ET)-l, an endogenous vasoconstrictive factor; however, there are few studies on the role of ET-1 receptor in the development of SU. Aims: To explore the significance of ET-1A receptor (ETAR) mRNA expression in the development of SU. Methods: The model of gastric ulcer was made by cold-restraint-stress (CRS) in rats. Plasma and gastric mucosal ET-1 levels were measured by radioimmunoassay method; and the expression of ETAR mRNA in gastric mucosa by reverse transcriptase polymerase chain reaction (RT-PCR) and dot blot prior to the stress and 1, 3, 6, 9, 12 hours afterwards in CRS rats. Gastric mucosal blood flow (GMBF) and ulcer index (UI) were measured simultaneously. Results: Both plasma and gastric mucosal ET-1 levels increased significantl'y (P<0.05). GMBF decreased markedly (P< 0.01), and UI increased dramatically (P<0.01) after stress as compared with the normal controls . There was significantly positive relationship between gastric mucosal ET-1 level and UI (r = 0.98, P<0.01), but not between the level of the plasma ET-1 and UI (r = 0.43, P>0.05). There was significantly negative relationship between gastric mucosal ET-1 level and GMBF (r=-0.89, P<0.08), but not between the level of plasma ET-1 and GMBF (r=-0.61, P>0.05). Also, a markedly negative relationship between GMBF and UI (r=-0.98, P<0.01) was found. Both RT-PCR and dot blot showed that the expression of ETAR mRNA in gastric mucosa of CRS rats increased significantly after stress compared with the normal controls (P<0.01). Significantly positive relationships between the expression of ETAR mRNA and ET-1 level of gastric mucosa (r=0.93, P<0.01), and between the expression of ETAR mRNA and UI of gastric mucosa (r = 0.95, P<0.01) were found. Conclusions: In CRS-induced ulcers in rats, the production of ET-1 and the expression of ETAR mRNA in gastric mucosa increase significantly. The increased endogenous ET-1 may be involved in the pathogenesis of gastric mucosal lesions in rats by binding to its receptors and inducing the reduction of GMBF.