不同剂量X线大分割照射对大鼠小肠的近期生物学效应

The Short Term Biological Effects by Different Doses of Hypofractiation to The Small Intestine of Rats

目的观察腹部大分割照射后大鼠小肠的形态学变化,并检测细胞凋亡基因Bax、Bcl-2的表达情况。方法将80只大鼠随机分为5组:空白对照组(0 Gy);4 Gy组(连续照射5次,每天1次);6 Gy组(照射3次,隔天1次);8 Gy组(照射2次,一周2次);12 Gy组(照射1次);各组于照射后第1、3、5、7天分别断头处死4只,取空肠组织,进行HE染色及免疫组化染色,光镜下观察病理变化,并检测Bax和Bcl-2的表达情况。结果与空白对照组比较,12 Gy、8 Gy照射组大鼠小肠黏膜损伤最重,4 Gy照射组次之,6 Gy照射组损伤较轻;所有照射组小肠Bax和Bcl-2基因表达水平均下降,与空白对照组相比有显著统计学差异(P<0.001),而不同照射剂量组间比较无统计学差异(P=0.101)。结论采用等效生物剂量为32 Gy的不同分割方式照射大鼠小肠后,小肠黏膜均出现不同程度损伤,而细胞凋亡基因Bax、Bcl-2表达水平均出现下降。

Objective To observe the morphology changes and the expression of apoptosis associated gene Bcl-2 and Bax in the small intestine of rats after hypofractionation radiation to their abdomen.Methods 80 rats were randomly divided into the following 5 groups：control group（without radiation,the 4 Gy group（one fraction each day for consecutive 5 days）,the 6 Gy group（for 3 fractions）,the 8 Gy group（for 2 fractions）,and the 12 Gy group（for 1 fraction）.4 rats each were killed in the 1st,3rd,5th,and 7th day after the radiotherapy.The morphological changes of jejunum tissues by HE stains and the expressions of Bcl-2 and Bax protein by immunohistochemistry were observed follow the above timeline.Results Comparing with the blank control group,the damage in the intestinal mucosa of the 12 Gy group and the 8 Gy group were the most serious,followed by the 4 Gy group,and the 6 Gy group was the lightest.The expression of Bcl-2 and Bax in the radiation groups was significantly decreased than that in the control group（P〈0.001）,but there was no statistical difference among the groups with different irradiation doses.Conclusion Different degrees of small intestine injury can be observed by radiation of equivalent biological dose of 32 Gy,and the expression of Bcl-2 and Bax is decreased.