AIM: To investigate the change of long-term potentiation ( LTP ) , and the expression of 5-hydroxytryptamine 1A receptor (5-HT1A receptor) and postsynaptic density protein 95 (PSD-95) in the hippocampus of the rats with posttraumatic stress disorder (PTSD), and to explore the mechanism of 5-HT1A receptor in the regulation of spatial memory in the PTSD rats.METHODS:Healthy adult SD rats (n=36) were randomly divided into control group and mod-el group, with 18 rats in each group.The rats in model group were treated with single prolonged stress to construct the mod-el of PTSD.Morris water maze ( MWM) was used to test the learning and memory ability .The LTP induced by high-fre-quency stimulation (HFS) was detected by electrophysiological method .The protein expression of 5-HT1A receptor and PSD-95 in the hippocampus was determined by Western blot and immunofluorescence .RESULTS: The MWM analysis showed that the latency of the rats searching for the underwater platform in model group was significantly longer than that in control group (P<0.01).The results of electrophysiological analysis showed that the amplitude of the evoked potential in both groups were significantly increased after HFS in the hippocampus , but that in model group was significantly lower than that in control group (P<0.01).The results of Western blot and immunofluorescence analysis showed that compared with control group, the protein expression of 5-HT1A receptor was obviously increased (P<0.05), while the expression of PSD-95 was obviously decreased in model group (P<0.05).CONCLUSION:The spatial memory impairment in the PTSD rats may be associated with the increase in the expression of 5-HT1A receptor and the decrease in the expression of PSD-95 in the CA1 region of hippocampus .%目的：观察创伤后应激障碍（ PTSD）大鼠海马长时程增强（ LTP）的变化以及5－羟色胺1A受体（5－HT1A受体）和突触后致密物蛋白95（PSD－95）的表达，探讨5－HT1A受体调控PTSD大鼠空间记忆的机制。方法：健康成年SD大鼠36只，随机分为正常对照组和模型组，每组18只。模型组采用连续单一刺激构建PTSD大鼠模型。 Morris水迷宫实验检测2组大鼠的学习和记忆能力，电生理实验检测强直性高频刺激对海马LTP的影响， Western blot法和免疫荧光实验检测海马5－HT1A受体和PSD－95蛋白的表达。结果： Morris水迷宫实验结果显示在各实验日模型组大鼠逃避平台的潜伏期较对照组显著延长（ P＜0．05）。电生理实验结果显示在强直性高频刺激后，2组大鼠海马诱发电位的幅值明显升高，模型组诱发电位的幅值显著低于对照组（P＜0．01）。 Western blot实验和免疫荧光实验结果显示，与对照组比较，模型组大鼠海马CA1区5－HT1A受体的表达显著增加（P＜0．05），但PSD－95的表达明显减少（ P＜0．05）。结论：PTSD大鼠空间记忆能力减退，可能与海马CA1区5－HT1A受体的表达增加和PSD－95的表达减少有关。
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