Effects of dexmedetomidine on enhancement of fear memory by propofol in rats with post-traumatic stress disorder / 中华麻醉学杂志

ABSTRACT

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=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 2<90% was recorded during administration.One hundred Sprague-Dawley rats were divided into 5 groups ( n=20 each) by the random number table method: propofol group (P2 group), and propofol+ dexmedetomidine given at different timings groups (P2+ DEX T0 group, P2+ DEX T30 group, P2+ DEX T60 group and P2+ DEX 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 T0, P2+ DEX T30, P2+ DEX T60 and P2+ DEX 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. Results:Only 6 rats developed SpO 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 ( P<0.05). Compared with PTSD group, the percentage of time of rigid behavior was significantly increased in P1 group ( P<0.05). Compared with P1 group, the percentage of time of rigid behavior was significantly decreased in P1+ DEX20 and P1+ DEX40 groups ( P<0.05), and no significant change was found in the percentage of time of rigid behavior in P1+ DEX10 group ( P>0.05). Compared with P2 group, the percentage of time of rigid behavior was significantly decreased in P2+ DEX T0 and P2+ DEX T30 groups ( P<0.05), and no significant change was found in the percentage of time of rigid behavior in P2+ DEX T60 and P2+ DEX T90 groups ( P>0.05). 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).