亚甲蓝对APP/PS1转基因小鼠学习记忆及海马结构内GFAP表达的影响

Effect of methylene blue on the learn and memory and expression of GFAP in hippocampal formation of APP/PS1 transgenic mouse

目的:观察亚甲蓝对APP/PS1转基因小鼠学习记忆及胶质纤维酸性蛋白(Glial fibrillary acidic pro-tein,GFAP)在海马结构表达变化的影响。方法:20只3月龄APP/PS1小鼠,随机分2组,每组10只,对照组:自由饮水;治疗组:根据小鼠饮水量将亚甲蓝加入日常饮水中(25 mg/kg/d)连用4个月至7月龄。水迷宫测试观察其行为学的改变,免疫组化、Western Blot和TUNEL染色法观察GFAP在海马结构的表达及神经元的凋亡情况。结果:水迷宫测试结果显示亚甲蓝喂养组APP/PS1转基因小鼠第2～4 d的平均潜伏期显著低于对照组小鼠的潜伏期,说明治疗组与对照组相比在7个月时出现明显差异(P<0.05);免疫组化和Western结果显示治疗组海马结构内的GFAP在APP/PS1转基因小鼠的表达下调(P<0.05)。TUNEL染色法显示治疗组海马CA1、CA3区和齿状回TUNEL阳性细胞数较对照组明显减少(P<0.05)。结论:亚甲蓝能够下调APP/PS1小鼠海马结构内GFAP蛋白的表达,并通过抑制海马结构神经元的凋亡,提高APP/PS1小鼠的认知能力。

Objective： To examine the effect of Methylene Blue on the the learn, memory and the expression of GFAP in hippocampal formation of APP/PS1 transgenic mice. Methods： 20 APP/PS1 transgenic mice were randomly divided into two groups with 10 in each. Mice in control group：received normal drinking water while mice in treatment group received drinking water mixed with MB （25 mg/kg/d）. Treatment was started when the mice were 3 months old and lasted until they were 7 months old. Morris water maze was used to test and observe the changes of behavior. Immunohistochemical staining, Western Blot and TUNEL staining were used to observe the expression of GFAP in hippocampal formation, and the apoptosis rate of neurons. Results： Morris water maze results shows that the average incubation of mice in MB fed group was much lower than that in control group, means comparing with the control group, the treatment group appears significant difference （ P 〈 0.05 ）. Immunohistochemical staining and Western Blot showed that the expression of GFAP in hippocampal formation of the mice in MB treated group was decreased （P 〈 0.05 ）. TUNEL stain showed that the positive expression in CA1, CA3 and DG of treated group was obviously lower than that of control group（ P 〈 0.05 ）. Conclusions： Methylene blue may down regulate the expression of GFAP in hippocampal formation of APP/PS1 mouse and improve the cognitive ability through inhibiting the apoptosis of neurons in hippocampal formation.