凋亡相关基因Bcl-2/Bax和Fas/FasL在应激性溃疡发生发展过程中的表达及作用

Expression and function of apoptosis-related genes Bcl-2/Bax and Fas/Fas L in the course of stress ulcer

目的 探讨应激性溃疡发生发展过程中 ,凋亡相关基因Bcl 2 /Bax、Fas/FasL表达的变化及其与细胞凋亡发生的关系。方法 SD大鼠按水浸 束缚应激 (WRS)实验 2h、3.5h及WRS结束后2、5、8、12、2 4h分 7组 ,每组 8只鼠 ,对照组 8只鼠。原位末端标记 (TUNEL)法检测WRS结束前后不同时间点细胞凋亡的发生情况 ;用原位杂交方法检测WRS结束前后大鼠胃粘膜组织Fas、FasL、Bcl 2mRNA的表达 ,免疫组化法检测Bcl 2 /Bax蛋白质的表达。结果 ( 1)正常大鼠胃粘膜上皮散在TUNEL细胞 ,WRS 2h～WRS后 5hTUNEL细胞较对照组明显增多 (P <0 0 1)并逐渐达高峰 ;WRS后 8～ 12hTUNEL 细胞逐渐减少 ,至WRS后 2 4h仍高于正常水平 (P <0 0 5 )。 ( 2 )正常对照组Fas、FasLmRNA无明显表达 ,FasLmRNA在WRS 3 5h至WRS后 8h在粘膜层基底部出现弱阳性～中等阳性表达。FasmRNA在WRS后 5～ 8h在粘膜层基底部出现弱阳性表达 ,WRS后 8h后表达基本消失。 ( 3)正常胃粘膜组织Bcl 2mRNA及蛋白质在胃腺部呈中等阳性表达 ,Bax蛋白质在上皮细胞层呈弱阳性表达 ;WRS 2h～WRS后 5hBcl 2表达明显减弱 (P <0 0 1) ,Bax表达增加并达高峰 (P <0 0 1) ;WRS后8～ 12hBcl 2表达增加 (P <0 0 1) ,Bax表达逐渐减弱 ,WRS后 2 4hBcl

Objective To investigate the correlation between the expressions of apoptosis-promoting gene Bax, apotosis-inhibiting gene Bcl-2, and Fas/FasL in gastric mucosa in the course of stress ulcer. Methods Fifty-six rats were exposed to water immersion-restraint stress (WRS) and then randomly divided into 7 groups of 8 rats: WRS 2 h, RS 3.5 h, and 2 h, 5 h, 8 h, 12 h, and 24 h after termination of WRS. Another 8 rats were used as controls. The stomachs of rats were taken out at the above mentioned time points to observe histologically. Terminal deoxynucleatidyl transferase mediated dUTP nick and labeling (TUNEL) technique was used to examine the apoptotic cells in the gastric mucosa. The expression of Bcl-2/Bax protein was examined by immunohistochemical assay. In situ hybridization was used to detect the mRNA expression of Bcl-2, Fas, and FasL. Results (1) Apototic cells were seen sporadically in the gastric mucosa of the control rats. The number of apoptotic cells began to increase since 2 hours after the beginning of WPS and reached its peak 5 hours after the termination of WRS. Since 8～12 hours after the termination of WRS the number of apoptosis began to decrease, however, still remained at a level significantly higher than the normal level (P<0.05). (2) Fas mRNA and FasL mRNA were not expressed in the controls. Fas mRNA was detected 5～8 hours after the termination of WRS at the base of mucosa at a low level and disappeared 8 hours after the termination of WRS. FasL mRNA was detected since WRS 3.5h to 8 hours after the termination of WRS. (3) In normal gastric mucosa, Bcl-1 mRNA and protein were expressed in gastric gland zone at a middle level and Bax protein was expressed in the epithelial cells. In WRS rats Bax protein expression began to be detected in the epithelial cells lining the gastric pits since WRS 2h, then increased, reached the peak 2～5 hours after the termination of WRS, and then gradually decreased and remained a little higher than normal level 24 hours later (P<0.05). Bcl-2 expression began to decrease since the termination of WRS and then increased 8～12 hours after the termination of WRS and reached the normal level 24 hours later (P>0.05). Correlation analysis showed that the expression of Bax protein was correlated with the quantity of apotosis in gastric mucosa. Conclusion The alterations of Bcl and Bax may be responsible for the development of mucosa lesion and recovery. The expression of Fas/FasL has no effect on the gastric mucosa apoptosis related to WRS. Overexpression of Bcl-2 may inhibit the Fas/FasL induced apoptosis.