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目的:评价右美托咪定对丙泊酚增强创伤后应激障碍(PTSD)大鼠恐惧记忆效应的影响。方法:清洁级健康雄性SD大鼠220只，体重300~400 g，12~16周龄，行条件性恐惧记忆训练，建立PTSD模型。取120只大鼠，采用随机数字表法分为6组(n n＝20)：对照组(C组)、PTSD组、丙泊酚组(P1组)、丙泊酚+右美托咪定不同给药剂量组(P1+DEX10组、P1+DEX20组和P1+DEX40组)。C组大鼠条件性恐惧记忆训练时仅播放声音，不予以电击；训练结束后，PTSD组腹腔注射芝麻油1 ml/kg，P1组腹腔注射丙泊酚1 ml/kg，P1+DEX10组、P1+DEX20组和P1+DEX40组分别腹腔注射右美托咪定10、20及40 μg/kg。给药结束后行条件性恐惧记忆检测，记录大鼠90 s内僵立行为时间，计算僵立行为时间百分比。记录给药期间SpOn 2<90%的发生情况。取SD大鼠100只，采用随机数字表法分为5组(n n＝20)：丙泊酚组(P2组)、丙泊酚+右美托咪定不同给药时机组(P2+DEXn T0组、P2+DEXn T30组、P2+DEXn T60组和P2+DEXn T90组)。条件性恐惧记忆训练结束后，5组均腹腔注射丙泊酚1 ml/kg，P2+DEXn T0、P2+DEXn T30、P2+DEXn T60和P2+DEXn T90组分别于丙泊酚给药后即刻、30、60和90 min时腹腔注射右美托咪定20 μg/kg。给药结束后行条件性恐惧记忆检测，记录大鼠90 s内僵立行为时间，计算僵立行为时间百分比。n 结果:给药期间仅P1+DEX40组有6只大鼠发生SpOn 2<90%。与C组比较，PTSD组僵立行为时间百分比增加(n P<0.05)；与PTSD组比较，P组僵立行为时间百分比增加(n P<0.05)；与P1组比较，P1+DEX20组和P1+DEX40组僵立行为时间百分比降低(n P0.05)。与P2组比较，P2+DEXn T0和P2+DEXn T30组僵立行为时间百分比降低(n P0.05)。n 结论:右美托咪定可减轻丙泊酚增强PTSD大鼠恐惧记忆的效应，中等剂量(20 μg/kg)早期给药(给予丙泊酚后30 min内)的效果最佳。“,”Objective:To evaluate the effects of dexmedetomidine on the enhancement of fear memory by propofol in rats with post-traumatic stress disorder (PTSD).Methods:Two hundred and twenty clean-grade healthy male Sprague-Dawley rats, weighing 300-400 g, aged 12-16 weeks, underwent conditioned fear memory training, and PTSD model was developed.One hundred and twenty rats were divided into 6 groups (n n=20 each) by a random number table method: control group (C group), PTSD group, propofol group (P1 group), and propofol + different doses of dexmedetomidine groups (P1+ DEX10 group, P1+ DEX20 group and P1+ DEX40 group). In group C, only sound was played and no electric shock was given during conditioned fear memory training.After conditioned fear memory training, sesame oil 1 ml/kg was intraperitoneally injected in PTSD group, propofol 1 ml/kg was intraperitoneally injected in group P1, and dexmedetomidine 10, 20 and 40 μg/kg were intraperitoneally injected in P1+ DEX10, P1+ DEX20 and P1+ DEX40 groups, respectively.After drug administration, conditioned fear memory test was performed to record the time of rigid behavior within 90 s, and the percentage of time of rigid behavior was calculated.The development of SpO n 2<90% was recorded during administration.One hundred Sprague-Dawley rats were divided into 5 groups (n n=20 each) by the random number table method: propofol group (P2 group), and propofol+ dexmedetomidine given at different timings groups (P2+ DEXn T0 group, P2+ DEXn T30 group, P2+ DEXn T60 group and P2+ DEXn T90 group). After the conditioned fear memory training, propofol 1 ml/kg was intraperitoneally injected in 5 groups, an then dexmedetomidine 20 μg/kg was intraperitoneally injected at 0, 30, 60 and 90 min after propofol administration in P2+ DEX n T0, P2+ DEXn T30, P2+ DEXn T60 and P2+ DEXn T90 groups, respectively.Conditioned fear memory test was performed after drug administration to record the time of rigid behavior within 90 s, and the percentage of time of rigid behavior was calculated.n Results:Only 6 rats developed SpOn 2<90% during the administration period in P1+ DEX40 group.Compared with C group, the percentage of time of rigid behavior was significantly increased in PTSD group (n P<0.05). Compared with PTSD group, the percentage of time of rigid behavior was significantly increased in P1 group (n P<0.05). Compared with P1 group, the percentage of time of rigid behavior was significantly decreased in P1+ DEX20 and P1+ DEX40 groups (n P0.05). Compared with P2 group, the percentage of time of rigid behavior was significantly decreased in P2+ DEXn T0 and P2+ DEXn T30 groups (n P0.05).n Conclusions:Dexmedetomidine can attenuate propofol-induced enhancement of fear memory in a rat model of PTSD, and the best effect is achieved in early administration of moderate dose (20 μg/kg, within 30 min after propofol administration).