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, P0 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.