氯胺酮对术后大鼠海马NMDAR亚单位蛋白表达的影响

目的观察氯胺酮对术后大鼠海马N甲基D天冬氨酸受体(NMDAR)亚单位表达的影响,探讨氯胺酮影响学习记忆的可能机制。方法将SD大鼠36只随机分为3组:对照组、模型组和氯胺酮组,每组12只。模型组和氯胺酮组按Brennan法制作大鼠趾部切口模型,对照组大鼠不作趾部切口。自手术切口即日起,氯胺酮组大鼠腹腔注射氯胺酮10mg/kg(1ml),对照组和模型组大鼠腹腔注射生理盐水1ml,1次/d,连续7d。术后3周进行水迷宫测试,4次/d,连续6d。水迷宫测试结束,断头处死大鼠分离海马,匀浆提取细胞膜蛋白,应用免疫印迹法测定NMDAR亚单位NR1、NR2A和NR2B表达的变化。结果自测试第1天至第6天,3组大鼠寻找平台的时间均逐渐缩短,但氯胺酮组大鼠平均寻找平台的时间较对照组或模型组显著延长(P<0.01或P<0.05)。与对照组和模型组相比,氯胺酮组大鼠海马NR2A和NR2B表达水平明显下调(P<0.05或P<0.01),而NR1的表达水平无明显变化;模型组大鼠海马NMDAR亚单位的含量与对照组相比差异无显著性意义。结论重复腹腔注射氯胺酮对趾部切口术后大鼠的学习记忆有明显影响,同时伴有NMDAR亚单位的改变。NMDAR表达的改变可能是氯胺酮导致认知功能损害的原因之一。

Effects of Ketamine on NMDA Receptor Subunits Expression in Hippocampus of the Plantar Incised Rats

Objective To investigate the effects of repeated administration ketamine on NMDA receptor expression in hippocampus of the plantar incised rats.Methods Thirty-six three-month-old Sprague-Dawley (SD) male rats weighing 200-250 g were randomly divided into three groups of 12 animals each: Control group, model group, and ketamine group. In the model group and ketamine group, a planter incision was made according to the methods of Brennan; the control group received a sham operation that consisted of anesthesia and sterile preparation of the hind paw but no incision. From the first day of planter incision, ketamine 10 mg/kg (1 ml) was given intraperitoneally in the ketamine group and normal saline 1 ml was given in the control and model group per day for 7 days. The Morris water maze testing was performed 4 times a day for 6 days after 3 weeks of planter incision. After completion of the testing on the final day, the animals were decapitated and the hippocampus was dissected away from the brains.The expression of NMDA receptor NR1, NR2A and NR2B protein in hippocampus was detected by using Western blotting.Results From the 1st to 6th days of Morris maze testing, the latency of the ketamine group was significantly longer than in the control group and the model group. Compared with the control group and the model group, the expression of NR2A and NR2B in the hippocampus of the ketamine group was decreased significantly and NR1 was not significantly changed. There was no difference in the NMDA receptor subunits expression between the control group and the model group.Conclusion Ketamine repeated administration might impair learning and memory performance and modify NMDA receptor subunits expression in hippocampus of plantar incised rats. The changes of NMDA receptor subunits expression might be one reason of cognitive deficit induced by repeated administration ketamine.