反复使用右美托咪定镇静对大鼠空间学习记忆功能的影响

Effects of repeated sedation with dexmedetomidine on spatial learning and memory function of the Sprague Dawlery rats

目的探讨反复使用同一剂量右美托咪定镇静对成年SD大鼠学习记忆功能的影响。方法 8周龄雄性SD大鼠24只,随机均分为三组:DEX组首先以6.0μg·kg-1·h-1速度静脉注射右美托咪定10min,继以3μg·kg-1·h-1维持镇静2h;NS组以生理盐水代替右美托咪定;BL组不采用任何操作;1次/天,连续5d。第6天行Morris水迷宫实验。行为学实验结束后,立即取大鼠海马组织行常规HE染色,并进行透射电镜观察海马组织超微结构的变化。结果在定位航行实验中,第1、2、3天DEX组潜伏期明显长于BL组(P<0.05)。常规染色和透射电镜观察海马形态学及超微结构,三组均无明显变化。结论在本实验条件下,成年SD大鼠接受右美托咪定反复镇静后,空间学习、记忆能力无明显影响,海马组织形态学及超微结构亦未见明显改变。

Objective To investigate the effects of repeated sedation with a certain dose of dexmedetomedine on spatial learning and memory function of the adult Sprague Dawley （SD） rats. Methods Totally 24 8-week-old male SD rats were randomly assigned to dexmedetomedine group （group DEX）, normal saline group（group NS） and blank group（group BL） with 8 rats in each group. The rats of group DEX were given a bolus dose of 6.0 μg·kg^-1·h^-1 dexmedetomidine with intravenous injection for 10 mins, following with 3.0μg·kg^-1·h^-1 infusion for 2 hours. The rats of group NS were administrated with the same volume of normal saline as group DEX. Group BL did not take any procedures. All the drugs were given daily, lasting for 5 days. On the sixth day, the Morris water maze was used in place navigation and spatial probe test to investigate the learning and memory function. After the behavioral experiments, the sections of hippocampus were prepared for the Hematoxylin-eosin staining. Meanwhile, the transmission electron microscope test were conducted to observe the ultrastructurae of the hippocampus. Results In place navigation, the latency of group DEX was significantly longer than that of group BL （P%0.05）. In hematoxylin-eosin staining and Transmission Electron Microscopy （TEM） experiments, there were no difference showed in hippoeampal neurons of rats among three groups. Conclusion Repeated sedation with dexmedetomidine have less effect on spatial learning and memory function of the SD rats, as well as the ultrastructurae of the hippocampus.