血管活性肠肽对大鼠内毒素性休克肠道损伤保护作用的研究

目的探讨大鼠内毒素休克模型的肠道病变、血液TNF-α、IL-1β、IL-10改变和血管活性肠肽（VIP）的保护作用。方法28只成年SD大鼠随机分成3组：对照组（8只）,内毒素休克组（10只）和血管活性肠肽干预组（10只）。内毒素休克组大鼠左侧颈外静脉注射内毒素10mg／kg,血管活性肠肽干预组注射同量内毒素后,即刻注射血管活性肠肽5nmol,对照组注射等容量生理盐水。各组于实验开始后1、2、4、6h分别留取血液,用ELISA法测定TNF—α、IL-1β和IL-10水平。大鼠自然死亡和实验持续6h时放血处死,留取小肠段,进行病理学检查。结果内毒素休克组和血管活性肠肽干预组血液TNF—α、IL-1β和IL-10水平与对照组相比呈现升高（P〈0．05 or P〈0．01）,其中TNF—α于2h时达到高峰点,IL-1β和IL-10持续升高至6h时间点。血管活性肠肽干预组TNF—α和IL-1β升高幅度低于内毒素休克组,IL-10升高幅度高于内毒素休克组（P〈0．01）。注射内毒素后小肠光镜和电镜下均显示肠段病变,内毒素休克组病变明显较血管活性肠肽干预组严重。结论血管活性肠肽可减轻内毒素休克大鼠肠道病变,其保护机制与下调促炎症细胞因子和上调抑炎症细胞因子的表达有关。血管活性肠肽是脓毒症休克治疗中有潜力的免疫调节物质。

Protective effects of vasoactive intestinal peptide on intestinal lesions induced by endotoxic shock in rat

OBJECTIVE: Vasoactive intestinal peptide (VIP) is a neuro-peptide that can modulate immunity in several aspects. Previous reports showed that VIP attenuates the deleterious consequences of severe infection and septic shock by regulating production of inflammatory cytokines in immune activated cells. Intestine is one of the major organ of immune system and it may trigger multiple organ dysfunction syndrome in sepsis. The present study was planned to study the change of serum TNF-alpha, IL-1beta, IL-10 level and histopathological alteration of intestinal tract, and protective effects of VIP on endotoxic shock in rat. METHODS: Twenty eight SD rats were randomly divided into 3 groups, including control group (8 rats), LPS shock group (10 rats), and LPS + VIP group (10 rats). Endotoxic shock model was established by administration of a single dose of 10 mg/kg LPS in LPS shock group, a bolus of 5 nmol VIP intravenous injection following LPS in LPS + VIP group. The rats in the control group were given the same volume of normal saline injection. Blood samples were taken at time points of 1, 2, 4, and 6 hours after intervention from each group for measuring the level of TNF-alpha, IL-1beta and IL-10 by ELISA. Pathological changes of the intestine were observed by light microscope and electron microscope at the animals death or at the end of the experiment. RESULTS: Serum TNF-alpha, IL-1beta and IL-10 levels elevated at each time point in LPS shock group and LPS + VIP group (P < 0.05 or P < 0.01). TNF-alpha concentration reached the peak level 2 h after LPS injection; IL-1beta and IL-10 increased continuously till the end of the experiment. In LPS + VIP group, TNF-alpha and IL-1beta elevated slightly and IL-10 increased significantly as compared with LPS shock group (P < 0.01). Leukocyte infiltration, ischemia, segmental hemorrhage or necrosis appeared in intestine under light microscope and cell swelling, cytoplasmic vacuoles and organelle damage were observed under electron microscope. However, pathological changes in LPS + VIP group were milder than those in LPS group. CONCLUSIONS: VIP improved endotoxic shock-associated histopathological alteration of intestine, down-regulated pro-inflammatory cytokines production and up-regulated anti-inflammatory cytokines. These effects may suggest a protective mechanism of VIP in septic shock. VIP is a potential immunoregulatory substance in treatment of septic shock.