正中神经电刺激脑外伤昏迷大鼠前额叶皮质5-HT 2A受体表达的实验研究

摘要

Objective:To investigate the expression of 5-HT 2A receptor in the prefrontal cortex of traumatic brain injuryinduced coma rats after median nerve electrical stimulation.Method:A total of 72 SD rats (weighing 250-300g) were randomly divided into 4 groups:a stimulationgroup,an antagonist group,a sham-stimulation group and a control group.This traumatic brain injury model was established by a weight-drop head injury,and we evaluated the change of behavior through the six classical levels of consciousness.The animals were sacrificed and their brain tissues were removed at 6,12,and 24 hours after injury.5-HT 2A protein expression was examined by immunohistochemistry.Result:Thirteen rats exhibited righting reflex in the stimulation group.In the antagonist group,9 rats exhibited righting reflex.5 rats in the sham-stimulation group had the same response.The mean rank of consciousness degree were degree 9.50 in the control group,degree 52.75 in the sham-stimulation group,degree 37.61 in the stimulation group,degree 46.14 in the antagonist group.Comparison among groups presented an increasing consciousness degree:control group＜stimulation group＜antagonist group＜sham-stimulation group(P＜0.01).Resuits from immunohistochemistry showed that significant differences in the 5-HT 2A expression among the four groups (sham-stimulation＜control＜antagonist＜stimulation))(P＜0.05),and a within-group comparison showed that the 5-HT 2A expression level was as follows:6 hours＜24 hours ＜12 hours(P＜0.05).Conclusion:Median nerve electrical stimulation might modulate wakefulness by promoting the 5-HT 2A expression via orexin-A in the prefrontal cortex of rats with traumatic brain injury-induced coma.%目的:研究正中神经电刺激对脑外伤昏迷大鼠前额叶皮质5-羟色胺(5-HT)2A受体表达的影响.方法:将72只SD大鼠随机分为空白组、假刺激组、刺激组和拮抗剂组共4组.采用经典的自由落体模型建立脑外伤昏迷模型及大鼠意识状态6级评定标准评估四组大鼠行为学变化,并于实验完成后6、12、24h用免疫组化技术检测各组大鼠前额叶皮质组织的5-HT 2A受体表达.结果:刺激组13只大鼠(72.22％)出现翻正反射,拮抗剂组9只(50％)、假刺激组5只(27.78％)出现翻正反射.空白对照组意识状态分级秩均值为9.50级,假刺激组为52.75级,刺激组为37.61级,拮抗剂为46.14级,四组的意识状态分级呈“空＜刺＜拮＜假”递增趋势,组间比较差异有显著性意义(P＜0.01).免疫组化结果显示组间比较前额叶5-HT 2A受体表达呈“空＜假＜拮＜刺”递增趋势(P＜0.05),组内比较呈“6h＜24h＜12h”趋势(P＜0.05).结论:正中神经电刺激可作为脑外伤后昏迷的一种有效促醒手段,其机制可能与前额叶皮质5-HT 2A受体水平上调有关,且Orexin-A可能在其中发挥调节作用.