脊髓GABAA受体在异丙酚对内脏痛大鼠镇痛效应中的作用

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190～240 g,进行鞘内置管,并于直肠粘膜下注射10%福尔马林100 μl.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5 μl、异丙酚10 μg、荷包牡丹碱2 μg;BP组先鞘内注射荷包牡丹碱2 μg,10min后鞘内注射异丙酚10 μg.注射福尔马林2 h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GABAA受体介导,对内脏痛大鼠产生镇痛效应.

Abstract：

Objective To evaluate the role of spinal cord CABAA 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 successfully 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 5 μl, 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 hnmuno-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.

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

Objective To evaluate the role of spinal cord CABAA 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 successfully 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 5 μl, 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 hnmuno-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.