内源性一氧化氮对大鼠应激性胃黏膜损伤的作用

目的探讨内源性NO在胃黏膜遭受应激损伤时的变化以及对胃黏膜损伤的作用。方法原位末端标记(TUNEL)法检测大鼠水浸-束缚应激(WRS)结束后2h细胞凋亡的发生;免疫组化的方法检测胃黏膜组织nNOS/iNOS蛋白表达的变化;原位杂交法检测细胞间隙连接蛋白43(CX43)mRNA表达变化,应激前腹腔内注射不同剂量的NO合成抑制剂N-单甲基左旋精氨酸(L-NAME),Griess法测定胃黏膜组织内NO含量,比较对黏膜损伤、细胞凋亡以及CX43表达的影响。结果WRS应激后2h胃黏膜损伤严重,细胞凋亡增加,iNOS表达增加,nNOS、CX43表达减少,小剂量L-NAME(2.0mg/kg)可降低胃黏膜损伤程度,降低凋亡细胞发生率34.6%(P<0.01),黏膜内NO含量减少(P<0.05),CX43表达增加(P<0.05);大剂量L-NAME(20.0mg/kg)明显增加凋亡细胞发生率25.8%(P<0.05),黏膜内NO含量明显减少(P<0.01),CX43表达减少(P<0.05)。结论应激状态下生成不同量的NO可减轻或加重黏膜损伤,抑制或促进凋亡发生。NO对细胞的损伤途径之一可能是通过影响细胞间隙连接的结构和功能。

Study on the effect of endogenous NO on stress-induced gastric mucosal lesions in rats

[Objectives] To determine the effect of endogenous NO on stress-induced gastric mucosal lesions in rats. [Methods] Apoptosis cells were quantitated in gastric mucosa by terminal deoxynucleatidy transferase mediared dUTP nick and labelling (TUNEL) techniques, and the expression of nNOS/iNOS proteins was detected by immunohistochemical approach. The expression of CX43 mRNA was detected by insitu-hyberdization. Different doses of nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME) were used to inhibit the synthesis of endogenous NO before immersion-restraint stress of rats, and NO contents in mucosa were measured by Griess reaction. [Result] Comparing with intact gastric mucosa of rats in non-exposed to WRS, severe mucosa lesion was detected at 2h after WRS, and the expression of iNOS protein increased, while the expression of nNOS protein and CX43mRNA decreased. In contrast to the normal sodium control grope, the small dose of L-NAME (2.0 mg/kg)partly decreased NO contents in mucosa , lessen the UI and quantity of apoptosis(P <0.01) and increased the expression of CX43 mRNA at 2h after WRS. But the high dose of L-NAME (20 mg/kg) obviously decreased NO contents in mucosa, aggravated theUI and quantity of apoptosis(P <0.01) and decreased the expression of CX43 mRNA. [Conclusion] Under stress condition, synthesis of endogenous NO with different contents could significantly mitigate or exacerbate the acute gastric mucosal injuries. The double-edged effect of NO might be partly due to regulation of the expression of CX.