大鼠烧伤后肠粘膜上皮细胞凋亡及其相关调控因子变化的研究

目的探讨大鼠烧伤后肠粘膜上皮细胞凋亡情况及相关调控因子变化的关系.方法 Wistar大鼠按随机数字表法分为烧伤组与正常对照组.动物于伤后6、12 h、1、3、5 d处死,流式细胞仪检测肠粘膜上皮细胞凋亡数,TUNEL法检测细胞凋亡形态学变化,RT-PCR法检测肠粘膜bcl-2 mRNA表达的变化,荧光法检测肠上皮细胞caspase-3酶活性.结果烧伤后6 h至5 d肠上皮凋亡细胞数较正常组明显增加;TUNNEL检测显示:烧伤后6 h阳性细胞数较正常组即有增加,伤后1 d表达最强,以后稍有减弱,但仍强于伤前;肠粘膜bcl-2 mRNA表达在伤后12 h开始低于正常,至伤后5 d仍低于正常,烧伤后大鼠肠上皮细胞caspase-3的活性在伤后1 d明显升高,伤后3 d到峰值,然后迅速下降至正常范围内.caspase-3活性变化与细胞凋亡数呈显著的正相关(r=0.56,P<0.05);烧伤后bcl-2 mRNA的表达与细胞凋亡数呈显著负相关(r=-0.72,P<0.05).结论烧伤后肠粘膜上皮细胞凋亡增加,尤以伤后1、3 d最为明显, caspase-3,bcl-2参与了烧伤后肠粘膜上皮细胞凋亡的调控.

Apoptosis of intestinal epithelial cells and changes of the related regulatory factors in severely burned rats

Objective To explore the relationship between the apoptosis of intestinal epithelial cells and changes of the related regulatory factors in severely burned rats. Methods Wistar rats, randomly divided into burn group and normal control group, were sacrificed at 0, 6, and 12 h, and 1, 3, and 5 d after burn. The apoptosis of intestinal epithelial cells, morphological changes of apoptotic cells, changes of bcl 2 mRNA expression, and activity of caspase 3 were detected by flow cytometry, TUNEL, RT PCR, and fluorescence method, respectively. Results Significantly increased apoptotic intestinal epithelial cells were found in severely burned rats. TUNEL test revealed that expression of positive cells increased at 6 h after burn, and the strongest expression was found at 1 d after burn, and decreased thereafter, but was till stronger than that before burn. Bcl 2 mRNA expression in intestinal epithelial cells was lower at 12 h after burn than the normal level and remained lower at 5 d after burn. The activity of caspase 3 significantly increased at 1 d after burn, reached the peak at 3 d after burn, and then dropped to the normal range in the burn group. The changes of the activity of caspase 3 were positively correlated with apoptotic cells ( r =0 56, P <0 05), but postburn bcl 2 mRNA was negatively correlated with apoptotic cells ( r =-0 72, P<0 05). Conclusion The apoptosis rate of intestinal epithelial cells increases after severe burn, particularly at 1 and 3 d after burn. caspase 3 and bcl 2 are involved in the regulation of apoptosis after severe burn.