食欲素A对脑外伤昏迷大鼠前额叶皮质Ras鸟嘌呤释放因子-1表达的影响

Effect of Orexin-A on RasGRF1 Expression in Prefrontal Cortex in Rats with Coma Induced by Traumatic Brain Injury

目的研究食欲素A(Orexin-A)对脑外伤昏迷大鼠的促醒作用及其对脑外伤后昏迷大鼠前额叶皮质中Ras鸟嘌呤释放因子-1(RasGRF1)蛋白表达的影响。方法将60只Sprague-Dawley大鼠随机分为5组:正常对照组、模型组、Orexin-A低剂量组、Orexin-A中剂量组和Orexin-A高剂量组,每组12只。采用自由落体撞击法建立脑外伤昏迷模型。应用立体定位注射技术,对正常对照组和模型组大鼠注射人工脑脊液,Orexin-A低剂量组、中、高剂量组大鼠分别注射不同浓度Orexin-A,观察行为学变化并使用western-blotting与免疫组织化学技术检测各组大鼠前额叶皮质中RasGRF1蛋白的表达量。结果正常对照组12只大鼠无昏迷,模型组0只苏醒,低剂量组4只苏醒,中剂量组中有8只大鼠苏醒,高剂量组2只苏醒;前额叶RasGRF1表达水平由低到高依次是:正常对照组<模型组<高剂量组<低剂量组<中剂量组(P<0.05)。结论 Orexin-A可显著改善脑外伤后大鼠的昏迷状态,其效果与浓度有关,作用机制可能与前额叶皮质区RasGRF1蛋白表达水平上调有关。

ObjectiveTo study the wake-promoting action of orexin-A and its effect on the expression of Ras-guanine nucleotide releasing factor-1（RasGRF1） in prefrontal cortex of comatose rats with traumatic brain injury（TBI）.Methods Sixty Sprague-Dawley rats were randomly divided into five groups： control group,model group,low-dose orexin-A group,medium-dose orexin-A group and high-dose orexin-A group,with 12 rats in each group.The model of TBI-caused coma was established using a weight-drop device.Rats in model group were stereotactically injected with artificial cerebrospinal fluid.Rats in low-,medium and high-dose orexin-A groups were treated with 1,3 and 5 nmol orexin-A,respectively.The changes in behaviors were observed,and the expression of RasGRF1 in prefrontal cortex was detected by Western-blot and immunohistochemistry.Results Among these rats,12 awakened in control group,none in model group,4 in low-dose orexin-A group,8 in medium-dose orexin-A group,and 2 in high-dose orexin-A group.The RasGRF1 expressed in an ascending order in control group,model group,high-dose orexin-A group,low-dose orexin-A group and medium-dose orexin-A group（ P 〈0.05）.Conclusion The orexin-A can dose-dependently improve the consciousness state of comatose rats with TBI,and its mechanism of action may be related to the up-regulation of RasGRF1 expression in prefrontal cortex.