内毒素预处理对内毒素血症大鼠各器官细胞凋亡的作用

目的　观察大鼠内毒素血症时各脏器的细胞凋亡及内毒素 (LPS)预处理对其作用。方法　将雄性Wistar大鼠 42只随机分为 3组 :生理盐水组 (N组 ,n =6) ;LPS对照组 (L组 ,n =18) ;LPS预处理组 (P组 ,n =18) ,P组 :首次 ,经腹腔注射LPS 0 .2 5mg/kg体重 ;2 4h后再经腹腔注射LPS 0 .5 0mg/kg体重 ,其余两组在上述时间均给予等量生理盐水 (NS) ;第 2次腹腔注射 72h后 ,L组和P组经静脉注入LPS 10mg/kg体重 ,N组给予等量NS。在静注LPS后 ,N组取 6只在 6h末、L组和P组分别在静注 2、4、6h时各取 6只大鼠处死。取动物肺、肝、小肠、脾等脏器组织 ,采用光镜、电镜及脱氧核苷酸末端转移酶介导的缺口末端标记法观察细胞凋亡。结果　内毒素血症时脾、肺、肝、小肠均出现不同程度的实质细胞和免疫细胞细胞凋亡增加 ,而内毒素预处理使上述器官的细胞凋亡明显减少 (P <0 .0 5 )。结论　内毒素预处理可减少大鼠内毒素血症时脾、肺、肝、小肠等脏器的实质细胞及免疫细胞的细胞凋亡 ,这可能是内毒素预处理保护作用的机制之一。

Effect of lipopolysaccharide pretreatment on apoptosis of visceral organs of rats with endotoxemia

Objective To observe the effect of lipopolysaccharide pretreatment on apoptosis of visceral organs of rats with endotoxemia.Methods Forty-two male Wistar rats were divided into three groups:saline group (N,n=6),LPS-treated group (L,n=18) and LPS-pretreated group (P,n=18).Rats in group P were first pretreated with introperitoneal injection of 0.25 mg/kg LPS dissolved in normal saline.After 24 h,they were subjected to the injection of 0.5 mg/kg LPS.Rats in groups N and L received an equivalent amount of saline.After 72 h,rats in groups L and P were challenged with intravenous injection of 10 mg/kg LPS.Six rats were killed 2,4,6 h after injection of LPS in each group.The lung,liver,small intestine,spleen tissues were removed quickly and stained with hemotoxylin-eosin and Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling (TUNEL),examined under electron microscopy at the same time.Results In group N,only a few scattered cells in spleen,lung,liver and small intestines displayed typical nuclei change indicative of apoptosis.In group L,spleen,lung,liver and small intestines contained many apoptotic cells,whereas in group P,apoptosis in spleen,lung,liver and small intestines was not increased.Conclusion Administration of a low dose of LPS before endotoxic challenge can significantly decrease apoptosis in spleen,lung,liver and small intestine,which may be one of protective mechanisms of LPS pretreatment.