苯二氮受体与吸入麻醉药镇痛、催眠作用的关系

Relationship between the analgesic and hyponotic effects of inhalation of volatile anesthetic and benzodiazepine receptor

目的探讨苯二氮受体与吸入麻醉药乙醚、恩氟烷、异氟烷和七氟烷对小鼠镇痛、催眠作用的关系。方法健康昆明种小鼠,体重18～24g,除热板试验仅用雌鼠外,其余雌雄兼用,按分层随机区组设计,使各组小鼠(n=10)的平均体重和性别比例相匹配。第一部分为镇痛实验,包括扭体试验、热板试验和福尔马林试验。每种试验用小鼠80只,分为乙醚组、恩氟烷组、异氟烷组和七氟烷组四大组,各组再分为生理盐水和氟马西尼两个亚组(n=10)。在各组分别注射乙醚、恩氟烷、异氟烷和七氟烷后,氟马西尼亚组静脉注射氟马西尼1mg/kg,生理盐水亚组静脉注射相同体积的生理盐水。除扭体试验采用皮下注射乙醚(1.0ml/kg)、恩氟烷(0.8ml/kg)、异氟烷(0.6ml/kg)及七氟烷(3ml/kg)外,热板和福尔马林试验均采取腹腔注射上述药物。热板试验中观察记录各鼠舔后足反应潜伏期即热板法痛阈(HPPT);扭体试验观察各组小鼠腹腔注射0.6%醋酸溶液10ml/kg后15min内小鼠的扭体次数;福尔马林试验将2%福尔马林20μl注射于小鼠左侧后肢足底皮下,观察记录Ⅰ相(10min)、Ⅱ相(10～60min)舔足时间(PLT)的变化。第二部分为催眠实验,小鼠80只,分组同上,分别腹腔注射催眠剂量的乙醚(2.0ml/kg)、恩氟烷(1.5ml/kg)、异氟烷(1.0ml/kg)和七氟烷(7.0ml/kg),待翻正反射消失后1min,按所分亚组分别静脉注射氟马西尼1mg/kg及等体积的生理盐水,记录翻正反射消失至恢复的时间(ST)。结果镇痛实验中,各吸入麻醉药在热板、扭体和福尔马林试验中均表现出明显的镇痛作用(P<0.05);但与生理盐水亚组比较,氟马西尼亚组HPPT、扭体次数和各时相PLT的差异均无统计学意义(P>0.05)。在催眠实验中,与生理盐水亚组比较,氟马西尼亚组ST的差异无统计学意义(P>0.05)。结论氟马西尼不能拮抗吸入麻醉药的镇痛、催眠作用。苯二氮受体并非乙醚、恩氟烷、异氟烷和七氟烷镇痛、催眠作用的主要靶位。

Objective To explore the relationship between the hypnotic and analgesic effects of inhalation of ethyl ether,enflurane,isoflurane or sevoflurane in mice and benzodiazepine receptor.MethodsMice of Kunming species weighed 18-24g were grouped with stratified random sampling,so that the mice of each group were of similar average weight and same gender （n=10）,and only female mice were used in hot plate tests.The first part was the experiment of the analgesic effect,which included twisting,hot plate and formalin tests.Eighty mice were divided into four groups （20 each） treated respectively with ethyl ether,enflurane,isoflurane and sevoflurane,and each group was then divided into two subunits （10 each） treated respectively with normal saline and flumazenil.Ethyl ether,enflurane,isoflurane or sevoflurane was subcutaneously injected,and animals in flumazenil subunits were intravenously injected with 1mg/kg of flumazenil,and those in normal saline subunits were injected with same volume of normal saline.Ethyl ether （1.0ml/kg）,enflurane （0.8ml/kg）,isoflurane （0.6ml/kg） or sevoflurane （3ml/kg） was injected hypodermically before twisting test,and they were given intraperitoneally in hot plate and formalin tests.Reaction latency of licking hindlimb （indicating pain threshold in hot-plate test,HPPT） was recorded in hot plate test,while times of body twisting were observed after injection of 0.6% acetum （10ml/kg） in 15 minutes.After injection of 2% formalin （20μl） into plantar surface of hind paw in formalin test,the changes of paw licking time （PLT） in I （in 10 minutes） and Ⅱ （10-60 minutes） phase were observed and recorded.Another 80 mice were involved in hypnosis experiment,and grouped and sub-grouped like that described in analgesic experiment.Each subunit was intraperitoneally injected with either ethyl ether （2.0ml/kg）,enflurane （1.5ml/kg）,isoflurane （1.0ml/kg） or sevoflurane （7.0ml/kg）.One minute after the disappearance of righting reflex,animals in flumazenil subunits were intravenously injected with flumazenil （1mg/kg）,and the same volume of normal saline was given to those in normal saline subunits.The time from disappearance to recovery of righting reflex （namely sleep time,ST） was recorded.ResultsIn the analgesic experiment,obvious analgesic effect was found in hot plate,twisting and formalin tests.Compared with normal saline subunits,no statistical significance existed in the reaction latency of feeling threshold,and times of body twisting and PLT in flumazenil subunits （P0.05）.In the hypnosis experiment,no significant difference in ST was found between normal saline subunits and flumazenil subunits （P0.05）.Conclusions Flumazenil can not antagonize the analgesic and hypnotic effects of inhalation of volatile anesthetic.Benzodiazepine receptor is not the major target for analgesic and hypnotic effect of ethyl ether,enflurane,isoflurane and sevoflurane.