中文摘要：

目的观察内毒素（LPS）预处理对内毒素血症鼠的作用并探讨其机制。方法将雄性Wistar大鼠72只随机分为生理盐水组（N组，n=24）、LPS对照组（L组，n=24）、LPS预处理组（P组，n=24），P组首先腹腔注射LPS，24h后再经腹腔注射LPS，N组和L组在上述两时点均给予等容量生理盐水，72h后L组和P组分别静脉注射LPS，N组给予等容量Ns。各组分别取6只大鼠用于持续观察血流动力学改变，并于造模后2、4、6h时分别另取6只大鼠采血测定肿瘤坏死因子-α（TNF—α）和一氧化氮（NO）含量，并于造模后6h取动物心、肺、肝、肾、小肠等脏器组织，观察其形态学变化。结果LPS预处理可明显逆转大鼠内毒素血症时的血流动力学如平均动脉压、心率和呼吸频率的改变：P组与L组比较差异有统计学意义，而与N组差异无统计学意义。L组大鼠血浆中TNF-α、NO的含量较N组、P组明显升高（P〈0．05），但N组与P组间差异无统计学意义。HE染色发现LPS预处理可减轻大鼠内毒素血症时心、肺、肝、肾、小肠的病理变化。结论LPS预处理可能通过减少TNF—α和NO的释放，对鼠LPS血症起到保护作用。

英文摘要：

Objective To investigate the effects and mechanism of lipopolysaccharide （LPS） pretreatment on endotoxemia in rats. Methods Male Wistar rats were randomly divided into three groups： saline group （N, n = 24）, LPS - treated group （ L, n = 24）, and LPS - pretreated group （ P, n = 24）. Intrapreitoneal injection of LPS was given to rats in Group P at baseline and 24th hour, while NS were given to rats in Group N and Group L instead. Intravenous injections of LPS were given to rats in Group L and P for construction of endotoxemia, while NS was given to Group N. The hemody- namics was observed constantly. TNF - α and NO levels were analyzed 2, 4 and 6 hours after modeling. The lung, heart, liver, kidney and small intestine tissues were stained with hemotoxylin and eosin for observation. Results The pretreatment of LPS significantly reversed the endotoxemia - induced hemodynamic change （ P 〈 0.05）. Significantly elevation of TNF - ct and NO were revealed in Group L, when comparing with those in Group N, which were significantly attenuated by pretreatment of LPS in Group P （ P 〈 0.05 ）. Moreover, significant alleviation in LPS - induced pathological impairment in heart, lung, liver, kidney and intestine were also observed in Group P. Conclusion Pretreatment of small dose of LPS protects rats from endotoxemia via reduction of TNF - α and NO.