电针对阿尔茨海默病小鼠学习记忆能力及海马细胞凋亡的影响

Electroacupuncture improves learning-memory ability possibly by suppressing apoptosis and down-regulating expression of apoptosis-related proteins in hippocampus and cerebral cortex in immature mice with Alzheimer’s disease

目的:观察电针阿尔茨海默病(AD)模型幼年小鼠"百会""风府"和双侧"肾俞"对其认知和学习记忆功能的影响及凋亡机制。方法:40只6周龄APP/PS1转基因雄性幼鼠作为AD模型,随机分为电针穴位组和AD模型组,每组20只;另选20只同月龄C57BL/6J雄性幼鼠作为正常对照组。电针穴位组小鼠电针"百会""风府"和双侧"肾俞",20 min/次,1次/d,每周休息1 d,连续治疗16周。采用水迷宫实验评价小鼠学习记忆能力;刚果红染色法和免疫组织化学法检测大脑皮层和海马的老年斑;TUNEL法检测小鼠海马神经元凋亡情况;蛋白免疫印迹法检测海马凋亡相关因子半胱氨酸蛋白酶3(Caspase 3)、B淋巴细胞瘤-2基因(Bcl-2)和Bcl-2相关X蛋白(Bax)的表达。结果:和正常对照组比较,AD模型组小鼠定位航行实验潜伏期明显延长(P<0.05);穿越原平台次数、平台象限停留时间明显减少(P<0.05);海马齿状回和大脑皮层的Aβ老年斑阳性表达量、海马齿状回凋亡细胞、Caspase 3和Bax表达明显升高(P<0.05)。与AD模型组比较,电针穴位组小鼠的定位航行实验潜伏期明显缩短(P<0.05);穿越原平台次数、平台象限停留时间明显增加(P<0.05);海马齿状回和大脑皮层的Aβ老年斑阳性表达量、海马齿状回凋亡细胞、Caspase 3和Bax表达明显下降(P<0.05)。结论:电针"百会""风府"和双侧"肾俞"可有效改善AD模型幼年小鼠的学习记忆能力,其机制可能与抑制海马神经元凋亡有关。

Objective To investigate the effect of electroacupuncture(EA)at"Baihui"(GV20),"Fengfu"(GV16)and bilateral"Shenshu"(BL23)on learning-memory ability,apoptosis in the hippocampus and expression of Aβ,Caspase 3,Bax and Bcl-2 proteins in the hippocampus and cerebral cortex in immature mice with Alzheimer’s disease(AD),so as to explore its mechanism underlying improvement of AD.Methods Forty APP/PS1 transgenic male young mice were equally randomized into model and EA groups and 20 C57 BL/6 J male young mice were used as the normal control.EA(10 Hz,about 2 mA)was applied to GV20-BL23 and GV16-BL23 for 20 min,once daily,6 days a week for 16 weeks.The Morris water maze swimming test was used to evaluate the animals’learning-memory ability.Congo red staining and immunohistochemical staining were used to detect senile plaques in the hippocampus(dentate gyrus)and cerebral cortex tissues.Terminal deoxynucleotidyl transferase-mediated dUTP Nick-end Labeling(TUNEL)was used to detect the cellular apoptosis of hippocampus.The expression levels of apoptosis related factors Caspase 3,Bax and Bcl-2 were detected by Western blot.Results After modeling,the escape latency of place navigation test of Morris water maze swimming tasks was significantly increased(P<0.05),while the number of platform crossing and residence time in the platform quadrant of spatial exploration test were significantly decreased in the model group in contrast to the normal control group(P<0.05).The number of apoptotic cells in the hippocampus and expression levels of Aβ,Caspase 3 and Bax proteins in the hippocampus and cerebral cortex were significantly up-regulated in the model group relevant to the normal control group(P<0.05).Following EA intervention,the escape latency of place navigation test of Morris water maze swimming tasks was significantly decreased(P<0.05),while the number of platform crossing and residence time in the platform quadrant of spatial exploration test were significantly increased in the EA group in contrast to the model group(P<0.05).The hippocampal apoptotic cells,the expression of Aβ,Caspase 3 and Bax proteins in hippocampus and cerebral cortex were evidently down-regulated in the EA group in contrast to the model group(P<0.05).Whereas the ratio of Bcl-2/Bax was significantly decreased in the model group relevant to the normal control group(P<0.05)and considerably increased in the EA group in contrast to the model group(P<0.05).No significant changes were found in the expression levels of Bcl-2 after modeling and after EA intervention(P>0.05).Conclusion EA of GV20,GV16 and BL23 can effectively improve the learning-memory ability in AD mice,which may be related to its function in inhibiting neuronal apoptosis in the hippocampus and down-regulating the expression levels of Aβ,Caspase 3 and Bax proteins in both hippocampus and cerebral cortex.