艾灸督脉对阿尔茨海默病转基因小鼠自噬水平及学习记忆能力的影响

Moxibustion improves learning-memory ability by promoting cellular autophagy and regulating autophagy-related proteins in hippocampus and cerebral cortex in APP/PS1 transgenic Alzheimer's disease mice

目的:通过观察艾灸督脉对APPswe/PS1de9(APP/PS1)双转基因阿尔茨海默病(AD)小鼠大脑皮层和海马自噬功能和β-淀粉样蛋白(Aβ)表达的影响,探讨艾灸督脉改善AD小鼠认知功能的作用机制。方法:AD小鼠随机分为模型组、艾灸组、西药Ⅰ组、西药Ⅱ组,同龄同背景C57BL/6J雄性小鼠作为正常组,每组10只。艾灸组小鼠隔附子饼灸"百会",温和灸"风府""大椎",每次20min,1次/d,治疗2周;西药Ⅰ组腹腔注射雷帕霉素,2mg·kg-1·d-1,治疗2周;西药Ⅱ组在艾灸治疗的同时腹腔注射3-甲基腺嘌呤,1.5mg·kg-1·d-1,治疗2周。各组小鼠分别于治疗前后行Morris水迷宫行为学检测。治疗结束后,用透射电镜观察小鼠大脑海马中自噬体的形成,免疫组织化学法检测小鼠皮层和海马区Aβ1-42的表达水平,Western blot法检测小鼠海马微管相关蛋白轻链3(LC3)、sequestosome-1(SQSTM1/p62)、磷酸化核糖体40S小亚基S6蛋白激酶(p-P70S6K)蛋白的表达水平。结果:模型组小鼠水迷宫实验逃避潜伏期较正常组延长(P<0.01);艾灸组和西药Ⅰ组与模型组比较,逃避潜伏期明显缩短(P<0.05)。透射电镜结果显示,模型组海马区神经元出现变形、不规则或萎缩,核膜粗糙不完整、双层结构模糊,胞质内自噬泡减少;艾灸组神经元仍有部分不规则变形、萎缩,胞质内可见自噬泡。免疫组织化学结果显示,与正常组比较,模型组大脑皮层和海马区Aβ1-42阳性细胞表达增多(P<0.01),并可见较多的老年斑;与模型组比较,艾灸组和西药Ⅰ组大脑皮层和海马区Aβ1-42阳性细胞表达减少(P<0.01)。Western blot结果显示,与正常组比较,模型组海马区中LC3-Ⅰ、p62、p-P70S6K蛋白表达水平明显增高(P<0.01),LC3-Ⅱ蛋白表达及LC3-Ⅱ/Ⅰ明显降低(P<0.01);与模型组比较,艾灸组、西药Ⅰ组海马区中LC3-Ⅰ、p62、p-P70S6K蛋白表达水平明显降低(P<0.01),LC3-Ⅱ蛋白表达及LC3-Ⅱ/Ⅰ明显升高(P<0.01)。结论:艾灸督脉改善AD转基因小鼠学习记忆能力/认知功能的作用,可能与上调细胞自噬水平,加速Aβ1-42清除,进而减少Aβ1-42沉积导致的神经细胞毒性损伤有关。

Objective To observe the effect of moxibustion of acupoints of the Governor Vessel on the levels of cellular autophagy,βamyloid protein(Aβ)immunoactivity,and expression of LC3-Ⅰ,LC3-Ⅱ,p62 and p-P70 S6 Kproteins in the hippocampal tissue of APPswe/PS1 de9(APP/PS1)double-transgenic Alzheimer’s disease(AD)mice,so as to reveal its underlying mechanisms in improving AD.Methods APP/PS1 double-transgenic AD mice were randomly divided into AD model,moxibustion,autophagyinducer(Rapamycin)and autophagy-inhibitor(3-MA)+moxibustion groups(n=10 in each group),and other 10 C57 BL/6 Jmale mice(the same age)were used as the normal control group.Herbal-cake(made of Chuanwu[Radix Aconiti Praeparata])partitioned moxibustion was applied to'Baihui'(GV20),moxibustion was applied to'Fengfu'(GV16)and'Dazhui'(GV14),all for 20 min,once daily for 2 weeks,with one day’s off between two weeks.For mice of the autophagy-inducer and 3-MA+moxibustion groups,Rapamycin(2 mg·kg-1·d-1)and 3-MA(1.5 mg·kg-1·d-1)were separately administered by intraperitoneal injection for 2 weeks.The cognitive ability was examined by Morris water maze tests,and the ultrastructural changes(including autophagic lysosomes,etc.)of hippocampal neurons were observed by using transmission electron microscopy.The immunoactivity of cerebral cortex and hippocampal Amyloidβpeptide 1-42(Aβ1-42)was detected by immunohistochemistry,and the expression levels of hippocampal LC3-Ⅰ,LC3-Ⅱ,p62 and p-P70 S6 Kproteins were detected by Western blot.Results After modeling,the escape latency of Morris water maze tasks was prolonged in the model group than in the normal control group(P<0.05)and obviously shortened in the moxibustion and autophagy-inducer groups(not the autophagy-inhibitor group)than in the model group(P<0.05).Results of transmission electron microscope showed deformed,irregular or atrophic neurons with rough and incomplete and fuzzy nuclear membrane,and decreased intracellular autophagosomes in the hippocampus in the model group,and partial irregular,atrophic neurons with more autophagic vesicles and lysosomes in the moxibustion group.The expression levels of Aβ1-42 in both cerebral cortex and hippocampus tissues,and LC3-Ⅰ,p62 and p-P70 S6 Kproteins in the hippocampus were considerably up-regulated in the model group relevant to the normal control group(P<0.01),and evidently down-regulated in both moxibustion and autophagy-inducer groups(not the autophagy-inhibitor group)than in the model group(P<0.01),while that of hippocampal LC3-Ⅱprotein and LC3-Ⅱ/Ⅰratio levels were obviously down-regulated in the model group relevant to the normal control group(P<0.01),and significantly up-regulated in both moxibustion and autophagy-inducer groups(not the autophagyinhibitor group)than in the model group(P<0.01).Conclusion Moxibustion can improve the cognitive ability of APP/PS1 double-transgenic AD mice,which is associated with its effects in promoting hip-pocampal and cerebral cortex autophagy level,and down-regulating the expression levels of Aβ1-42,LC3-Ⅰ,p62 and p-P70 S6 Kproteins in the hippocampus.