脊髓GABAA受体在异丙酚对内脏痛大鼠镇痛效应中的作用

Role of spinal cord GABAA receptors in the analgesic effect of propofol on visceral pain in rats

目的评价脊髓γ-氨基丁酸A（GABAA）受体在异丙酚对内脏痛大鼠镇痛效应中的作用。方法成年健康雌性SD大鼠，体重190—240g，进行鞘内置管，并于直肠粘膜下注射10％福尔马林100μl。取鞘内置管成功的大鼠32只，采用随机数字表法，将其随机分为4组（n=8）：二甲基亚砜组（D组）、异丙酚组（P组）、荷包牡丹碱组（B组）和荷包牡丹碱＋异丙酚组（BP组）。D组、P组和B组分别鞘内注射二甲基亚砜5μl、异丙酚10μg、荷包牡丹碱2μg；BP组先鞘内注射荷包牡丹碱2μg，10min后鞘内注射异丙酚10μg。注射福尔马林2h时，取脊髓L5～S1节段，采用免疫组化法测定FOS蛋白表达水平。结果与D组和B组比较，P组脊髓FOS蛋白表达下调（P〈0．05）；D组和B组脊髓FOS蛋白表达差异无统计学意义（P〉0．05）；与P组比较，BP组脊髓FOS蛋白表达上调（P〈0．05）。结论异丙酚可通过脊髓GABA。受体介导，对内脏痛大鼠产生镇痛效应。

Objective To evaluate the role of spinal cord GABAA receptors in the analgesic effect of propofol on visceral pain in rats. Methods Adult female SD rats, weighing 190-240 g, were used in this study. The animals were anesthetized with intraperitoneal ketamine 50-100 mg/kg. Intrathecal （IT） catheters were placed at L5.6 interspace according to the technique described by Storkson et al. Thirty-two animals in which IT catheters were successfuUy placed were randomly divided into 4 groups （ n = 8 each） ： dimethyl sulphoxide （DMSO） group （group D）, propofol group （group P）, bicuculline group （group B） and bicuculline ＋ propofol group （group B ＋ P）. Visceral pain was induced by injecting 10% formalin 100 μl underneath the mucous membrane of rectum. Groups D, P and B received IT DMSO 5μl, propofol 10 μg and bicuculline 2 μg respectively. Group BP received IT bicuculline 2 μg and then IT propofol 10 μg 10 min later. The L5-S1 segment of the spinal cord was removed 2 h after formalin injection to determine FOS protein expression by immuno-histochemistry. Results Compared with groups D and B, FOS protein expression was significantly down-regulated in group P （P 〈 0.05）. There was no significant difference in FOS protein expression between groups D and B （ P 〉 0.05）. FOS protein expression was significantly up-regulated in group BP compared with group P （P 〈 0.05）. Conclusion Propofol has analgesic effect on visceral pain in rats through spinal cord GABAA receptor action.