LRG在脂多糖预处理诱导大鼠脑保护效应中的作用研究

Study on the function of LRG on the cerebral protection induced by lipopolysaccharide preconditioning

目的:通过测定不同组大鼠脑缺血/再灌注损伤模型中脂多糖应答基因分子(lipopolysaccharideresponsegene,LRG)表达水平的变化与血浆降钙素基因相关肽(CGRP)、内皮素(ET-1)、肿瘤坏死因子-α(TNF-α)含量及大鼠神经功能评分和脑梗死容积之间的关系,探索脂多糖(lipopolysaccharide,LPS)预处理诱导脑保护效应的核心分子机制。方法:将SD大鼠随机分为假手术组、缺血对照组和脂多糖预处理组。采用戊巴比妥钠(40mg/kg)腹腔注射麻醉大鼠,采用大脑中动脉栓塞模型制备大鼠脑缺血/再灌注模型。免疫印迹法结合图像分析软件半定量计算LRG分子表达水平的变化,放射免疫法测定血浆CGRP、ET-1和TNF-α浓度,采用garcia评分法进行神经功能评分,用氯化三苯四唑(TTC)染色法和计算机图像分析系统计算脑梗死容积。结果:相比于缺血对照组,脂多糖预处理组大鼠脑缺血/再灌注后72hLRG表达水平明显上调,血浆CGRP浓度显著增高,而血浆ET-1和血清TNF-α浓度则显著降低,同时,脂多糖预处理组大鼠神经功能评分较缺血对照组明显改善,脑梗死容积也显著缩小。结论:脂多糖预处理可诱导LRG分子表达水平上调,显著降低ET-1、TNF-α而增加CGRP浓度,从而对急性脑缺血再灌注损伤产生一定的保护效应。

Objective To explore the core molecular mechanism of lipopolysaccharide（LPS）preconditioning to induce the cerebral protection through to test change of expression of lipopolysaccharide response gene （LRG） in rat＇s model with reperfusion injury after cerebral ischemia and relationship among calcitonin gene related peptide （CGRP）, endothelin （ET-1）, tumor necrosis factor-α （TNF-α）, scores of neurological function and infarct volumes. Methods Spraque：Dawley rats were radomly divided into sham, control and LPS groups.Intraperitoneal injection with pentobarbital sodium （40 mg/kg） was used for rats anesthesia and model of reperfusion was induced by middle cerebral artery occlusion. The change of expression of LRG was counted in semiquantitative method by immunoblotting combined with image analysis software. The content of CGRP, ET-1 and TNF-α were measured by radioimmunoassay. Garcia method was used to score the neurological function and triphenyl tetrazolium chloride （TTC） and computer aided video system were used to measure the infarct volumes. Results The expression of lipopolysaccharide response gene （LRG） and level of CGRP in LPS group were significantly increased compared with control group after 72 hours from reperfusion of cerebral ischemia, while the content of ET-1 and TNF-α were reduced obviously. Accordingly, the neurological behavior scores were better in LPS group than those in control group, the infarct volumes in LPS group were significantly smaller than those in control group （P 〈 0.05）. Conclusion Pretreatment of LPS can induce upregulation of LRG expression, decrease the concentration of ET-1 and TNF-α but increase the concentration of CGRP thus produce certain protective effects on reperfusion injury of acute cerebral ischemia.