异氟醚对部分脑啡肽神经元激活的作用及其机制

Effect and mechenism of isoflurane on activation of enkephalin-containing neurons

目的:观察异氟醚诱导大鼠中枢神经系统各核团Fos蛋白与脑啡肽的表达及共存情况。方法:SD大鼠12只,随机分为对照组和异氟醚组,每组6只。异氟醚组吸入20mL/L异氟醚2h,对照组吸入氧气。取脑和脊髓,冰冻切片,进行Fos蛋白与脑啡肽的免疫组织化学双重染色。结果:对照组中,脑啡肽免疫反应阳性(ELI)神经元较多,Fos免疫反应阳性(FLI)神经元少量、散在无规律地分布,Fos,脑啡肽双标记(FLI/ELI)神经元极少见。异氟醚组中可明显观察到ELI,FLI,FLI/ELI3种神经元,主要分布在大脑额顶皮质、外侧隔阂、杏仁核、海马CA1区、丘脑室旁核、丘脑腹外侧核、僵核、下丘脑腹内侧核、视上核、视交叉上核、脚间核、中脑中央灰质及脊髓背角等神经核团,这些核团内FLI和ELI神经元数量与对照组比较显著增多(P<0.05或P<0.01),在其他核团内无显著变化;Fos与脑啡肽神经元彼此靠近,分布区域非常一致,FLI/ELI神经元占FLI神经元的15%～42%。结论:异氟醚可诱导Fos蛋白在某些神经核团内表达并使其内脑啡肽增多;异氟醚可激活部分脑啡肽神经元,麻醉诱导的Fos蛋白可能作为脑啡肽基因的转录调控因子,进而引起脑啡肽的变化。

AIM:To observe the expression and coexistence of Fos protein and enkephalin in central nervous system of rats induced by isoflurane. METHORDS:Twelve SD rats were randomly divided into 2 groups:control group and isoflurane group(6 in each group).The rats in the isoflurane group inhaled 20 g/L isoflurane for 2 hours and those in the control group inhaled O2. The brain and spinal cord of rats were removed and sliced under frozen condition.Double labeled immunohistochemical technique for Fos protein and enkephalin was used. RESULTS:The control group showed much enkephalin like immunoactivity (ELI) neurons, few Fos like immunoactivity(FLI) neurons and rare Fos enkephhalin double labeled(FLI/ELI) neurons.The isoflurane group showed FLI,ELI and FLI/ELI neurons obviously.They mainly distributed in frontalcortex,lateral septal nucleus,basolateral amygdaloid nucleus,hippocampus CA1,paraventricular nucleus,ventral posterolal nucleus,habenular neuleus,ventromedial hypoth nucleus,supra optic nucleus,suprachiasmatic nucleus,interpeduncular nucleu,central gray substance of midbrain and dorsal horn.Compared with control group,the number of FLI,ELI neurons in these nuclei were significantly high in these nuclei(P< 0.05 or P< 0.01)and had no significant change in other nuclei.The Fos and enkephhalin labeled neurons coincided with each other.Furthermore,FLI neurons were adjacent to ELI neurons.FLI/ELI neurons were approximately 15%to 42%of FLI neurons. CONCLUSION:Isoflurane can induce Fos expression in some nuclei and increase enkephhalin level in them.The coexistence of Fos and enkephhalin suggests that isoflurane can activate enkephhalin containing neurons.Fos protein induced by anesthetics probably might function as the transcription regulator of preproenkephalin gene,which indirectly led to the changes of enkephalin level.