Objective To observe the effect of propofol on neuronal MMP-9 expression after brain injury in rats and to explore its action mechanisms in neuroprotective effects .Methods Ninety-one health male Wistar rats were randomly divided into sham-operation group , saline group ( saline treatment after brain injury ) , propofol group ( propofol treatment after brain injury).Propofol dose was clinical anesthesia relevant dose (100mg/kg),which was injected intraperitoneally 15 min afterbrain frostbite ,once every 2 hours.The brain frostbite models were established by skull external intelligence frostbite method,then the brain tissues were collected at 2, 6,24 hours after frostbite.The brain water content was detected by dry wet weight method;the expression levels of MMP-9 mRNA were detected by RT-PCR;expression levels of MMP-9 protein were detectedby immunohistochemistry .Results The brain water content in saline group in different time points was significantly higher than that in sham-operation group( P <0.01),which peaked at 24 hours after brain frostbite.The brain water content in propofol group was significantly lower than that in saline group at 6,24 hours after brain frostbite( P <0.05 or P <0.01). The expression levels of MMP-9 mRNA in sham-operation group were decreased , however , which in saline group were significantly increased at 2 hours after brain frostbite,as compared with those in sham-operation( P <0.01),which peaked at 6 hours,continued at 24 hours( P <0.01).The expression levels of MMP-9 mRNA in propofol group were significantly decreased at 6,24 hours after brain frostbite,as compared with those in saline group( P <00.5 or P <0.01).The expression levels of MMP-9 protein in saline group were significantly increased at 2 hours after brain frostbite ,as compared with those in sham-operation group,which peaked at 6 hours,continued at 24 hours( P <00.1 ).The expression levels of MMP-9 protein in propofol group were significantly decreased at 6h,24h after brain frostbite,as compared with those in saline group ( P <0.05 or P <0.01).Conclusion Propofol at clinical anesthesia relevant dose can relieve brain edema after brain injury ,which may be correlated to the inhibitory effect of propofol on expression of MMP-9.%目的：观察异丙酚对大鼠脑损伤后脑组织MMP9-表达的影响，探讨异丙酚的脑保护作用机制。方法91只雄性Wistar大鼠随机分为假手术组、伤后0．9％氯化钠溶液组、伤后异丙酚治疗组。异丙酚给药量为临床麻醉相关剂量（100 mg/kg）：冷冻伤后15 min腹腔注射异丙酚50 mgk/g 1，次/2 h后再次追加相同剂量。采用颅骨外脑冷冻伤法，运用液氮冷冻器局部冷冻大鼠左侧顶部脑组织60 s制作冷冻伤即脑损伤模型。分别于冷冻伤后2、6、24 h处死并收集脑组织标本，采用干湿重法测定脑水含量， RT-PCR 法检测MMP-9基因的mRNA表达，免疫组化法测定MMP-9的蛋白表达。结果伤后0．9％氯化钠溶液组在伤后各时点伤侧脑组织含水量均显著高于假手术组（ P ＜0．01），脑冷冻伤后24h 最高；在伤后6 h、24 h，伤后异丙酚治疗组脑组织含水量与0．9％氯化钠溶液组比较均显著降低，差异有统计学意义（ P ＜0．05或＜0．01）。假手术组脑组织MMP9-mRNA水平表达很低，脑冷冻伤后2 h，0．9％氯化钠溶液组MMP-9 mRNA水平较假手术组明显升高，6 h最高，24 h仍保持在较高水（ P ＜0．01）；在伤后6 h及24 h，伤后异丙酚治疗组脑组织MMP-9 mRNA水平与0．9％氯化钠溶液组比较均显著降低，差异有统计学意义（ P ＜00．5或＜0．01）。假手术组脑组织MMP-9蛋白未见明显阳性表达，脑冷冻伤后2 h，0．9％氯化钠溶液组MMP9-蛋白阳性表达水平较假手术组明显升高，6 h最高，24 h仍保持在较高水平（ P ＜0．01）；在伤后6 h及24 h，伤后异丙酚治疗组脑组织MMP9-蛋白表达水平与0．9％氯化钠溶液组比较均显著降低，差异有统计学意义（ P ＜0．05或＜0．01）。结论临床麻醉相关剂量的异丙酚可以减轻脑损伤后脑水肿。此种作用可能与异丙酚抑制MMP-9的表达有关。
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