表皮生长因子增强TPN减少放射性肠炎细菌易位及其机理的实验研究

Epidermal growth factor reduces bacterial translocation and its mechamisms in parenteral fed rat following abdominal radiation

腹部受辐射 ( abdominal rdiation,AR)致放射性肠炎常导致肠粘膜屏障损害和细菌易位。接受长期 TPN( total parenteral nutrition,TPN)改善营养的同时 ,可加重细菌易位 ,并导致多器官功能衰竭等致死性并发症。即使给予肠粘膜代谢所需的谷氨酰胺 ( Glutamine,Gln)亦不能完全防治其损伤。EGF( epidermal growth factor)是胃肠道粘膜上皮生长和增殖的介质。本研究在 SD大鼠放射性肠炎模型上观察了 EGF增强 TPN对放射性肠炎细菌易位及对损伤的肠粘膜修复的影响 ,结果发现 ,经 EGF增强的 TPN治疗大鼠放射性肠炎 ,大鼠死亡率、细菌易位率均较不用 TPN及应用不含 EGF的 TPN组明显下降 ,体重、粘膜 /肠段重量比、绒毛高度、面积、小肠 Gln摄取率及 DNA含量均明显升高。机理为 :EGF对小肠粘膜有明显的滋养作用。EGF增强 TPN在提供较完善营养及肠道充分休息 ,促进创伤愈合的同时 ,通过提高肠粘膜对 Gln的摄取能力 ,维持肠粘膜上皮的正常代谢 ,加速修复损伤的肠粘膜屏障 ,降低细菌易位率 。

A major effect of abdominal radiation(AR) is the production of radiation enteritis.This damages the gut mucosa barrier and leads to bacterial translocation(BT) from gut tract. Radiation enteritis may require long- term total parenteral nutrition (TPN ) which could promote bacterial translocaton and lead to MOF.Even a good supply of glutamine(Gln) will not provide full protection to the small intestine mucosa from radiation injury.Epidermal growth factor(EGF) stimulates proliferation and maturation of the intestinal mucosa cell throughout the gastrointestinal tract.A series of experments has been carried out to observe the effect of EGF in parenteral fed rat following abdominal radiation.After9.5 Gy of60 Co radiation,rats were separated randomly into four groups:Group B(n =1 8) ,AR + sham operaton;group C(n=1 8) ,AR+ TPN;group D(n=1 8) ,AR+ EGF+ TPN;Nine rats were selected at random from each group in day7and1 4following irradiation.Group A(n=8) as a namal group.Rats were observed for mortality,changes of body weight,mucosa weight/ weight of intestinal section,mucosa DNA.The BT in mesenteric lymph node(MLN) ,liver, spleen,peritoneal cavity and blood was examined,glutamine extraction in intestinal mucosa were determined.Results:When EGF was administered along with TPN in the radiaton enteritis rat,the body weight loss,bacterial translocation and motality were decreased,and the mucosa weight/ weight of intestinal segment,villous hight and area,mucosal DNA,and gut glutamine extraction were increased significantly.Conclusion:L ong- term TPN,EGF could develop the ability of gut to extract available Gln from the circulation and gut,promote the repaire of gut mucosa barrier,decrease the rate of bacterial translocation and decrease the motality.