甲状腺激素水平变化对大鼠空间学习及记忆的影响

Effects of thyroid hormone levels on spatial learning and memory in rats

目的探讨甲状腺激素水平变化对Wistar大鼠空间记忆的影响。方法挑选健康8周龄Wistar大鼠30只,体质量(200±30)g,适应性喂养1周后,将30只Wistar大鼠随机分为对照组、甲状腺功能减退组(甲减组)及甲状腺功能亢进组(甲亢组),将Wistar大鼠行双侧甲状腺完全切除手术,术后28 d建立甲减模型;每天给予正常Wistar大鼠皮下注射甲状腺素20μg/100 g体质量,共28 d建立甲亢模型。模型建立结束后对3组大鼠分别行Morris水迷宫实验(包括定位航行实验和空间探索实验),观察各组大鼠在空间学习、记忆能力方面的差异。结果行为学检测表明,与对照组大鼠比较,甲减组及甲亢组大鼠在定位航行实验中逃避潜伏期明显延长;甲减组与甲亢组空间探索实验能力明显下降,表现在2组的目标象限路程、时间延长,穿越目标次数减少,差异均具有统计学意义(P值均<0.05)。结论成年期甲减或甲亢Wistar大鼠会出现空间学习、记忆能力的下降。

Objective To assess the effect of thyroid hormone levels on spatial memory in Wistar rats.Methods Healthy 8-week-old Wistar rats[N=30,approximately(200±20)g,after 1 week of adaptive feeding]were used in this study.The rats were randomly and equally divided into a control group,a hypothyroidism group and a hyperthyroidism group.Normal Wistar rats underwent bilateral thyroidectomy to establish a hypothyroidism model.Hypothyroidism was established 28 days after operation.Normal Wistar rats were injected subcutaneously with thyroxine 20μg/100 g body weight each day for 28 days to establish a hyperthyroidism model.The Morris water maze test(including navigation and space exploration experiments)was performed on the three groups of rats after the establishment of the models to observe their difference in spatial learning and memory ability.Results Compared with control group rats,the escape latency was significantly prolonged in the navigation experiment and the space exploration ability decreased significantly in the hypothyroidism group and hyperthyroidism group,which manifested as statistically significant extended distance and time in the target quadrant and reduced number of passes through the target(P<0.05 for all).Conclusion Hypothyroidism or hyperthyroidism can lead to a decrease of spatial memory in Wistar rats.