| Beta-Amyloid(Aβ)cascade theory is the most recognized pathogenesis of Alzheimer’s disease (AD). This hypothesis believes when the clearance of Aβ in the brain is failture,it will leading to excessive deposition of Aβ in the brain parenchyma,and the formation of senile plaques, and final resulting in neurofibrillary tangle, neurotoxicity and other pathological changes in AD. This pathological leading to the cognitive impairment of AD patients. The key of AD treatment is increase Aβ clearance or decrease Aβ production.The function of cerebral microvascular play a important role in the early stage of Aβ clearance stage in brain.When the function of cerebral microvascular in Aβ clearance is failture,the Aβ will deposits on brain microvascular wall,which may damage the structure of microvascular wall(mainly of endothelial cell, basement membrane and pericytes).This will lead to the further aggravate of brain microvascular function in AP clearance, the senile plaque formation and cognitive impairment.In traditional Chinese medicine theory, the pathogenesis of dementia is the deficiency in the standard,the disease is mainly in the brain, deficiency of kidney essence deficiency, brain insufficiency or blood decline less, brain displaced. But the disease cloud Mongolia orifices spirit losing or congestion accumulated for a long time, the brain raises. The phlegm and blood stasis, phlegm and toxin Blocking Collaterals of the brain caused by dementia spirit losing. This related to the dysfunction of the vascular clearance pathway in Aβ cascade, which leads to the Aβ deposit cerebral microvascular wall, the Chinese tradition medicine initiates a therapeutic principle called "waking God, nourishing kidney, removing toxin and dredging collaterals",which has provided a theoretical basis for the treatment of deposit on cerebral microvascular wall by acupuncture.ObjectiveThis experiment choose Immunogold electron microscopy,immunohistochemistry and thioflavine S staining to test the level of AP deposition on the cerebral microvascular wall.from the view of morphology to demonstrated whether electroacupuncture can improving the ability of cerebral microvascular in Aβ clearance, so that reduce the level of Ap deposition on microvascular wall in brain, then reduce the level of senile plaques in brain parenchyma, finally improve the learning and memory ability impairment of APP/PS1 mice.Methods7-month-old APP/PS1 double transgenic mice were randomly divided into model group(M),EA group(EA),Non-transgenic litter-mate mice were used as control(C). Mice in EA group were given acupunctured Yongquan, Baihui 0.1mA,15min,1 time every other day,for 6 week.The 2nd-5th day after treated,they all had taken Morris water maze test. Using the escape latency in place navigation test, the times across the platform, the swimming time in platform quadrant to evaluate the electroacupuncture treatment effect on cognitive impairment.Then select 6 mice randomly from every group, using right side of the brain with Thioflavin S method to detect senile plaque levels, and immunohistochemical was used to detect the Aβ1-40 and Aβ1-42 levels on cerebral microvascular wall and the condition in senile plaque. Using the CA1 location of left brain with Immunogold electron microscopy to location the Aβ1-42 on ultrastructure of cerebral microvascular wall(mainly on endothelial cell, basement membrane and pericytes) and senile plaque.Results1,The Morris water maze test showed the escape latency was significant different (P>0.05),which Model group(M) escape latent time longer than that of the blank control group(C), the difference was statistically significant(P<0.05); Electroacupuncture group(EA) escape latency was shorter than that of model group (M), the difference is statistically significant(P<0.05). but the number of platform-site crossover,the time spent in platform quadrant,which we put the mice in the frist quadrant ineach group were not significant different(P>0.05).2.The immunohistochemistral result show that Ap was appeared positive expression mainly on senile plaque and cerebral microvascular wall in the hippocampus of model group and electroacupuncture treatment group, the IOD of Aβ1-40 and Aβ-42 on the Cerebral microvascular wall in model group is higher than contral group (P<0.05,P<0.05), the IOD of Aβ1-40 and Aβ1-42 on the Cerebral microvascular wall in EA group is lower than that in model group(P<0.05,P<0.05).3. Thioflavine S staining results show that the hippocampus of model group and electroacupuncture treatment group had developed a number of senile plaque. The plaque number and plaque burden of model group is higher than that in control group, which had significant different(P<0.05,P<0.05); The plaque number and plaque burden of EA group is lower than that in model group, which had significant different(P<0.05,P<0.05).4. Immunogold electron microscopy results show that senile plaques were observe in the hippocampus of model group and EA group. Colloidal gold particles were mainly gathered in the senile plaques, endothelial cells,pericytes and membrane, the colloidal gold particle density on cerebral microvascular wall (endothelial cells, pericytes and basement membrane) in model group was highest, which EA treatment group secondly, and the blank control group was the lowest.ConclusionThe mechanism of electro-acupuncture in the treatment of AD may be through improving the ability of Aβ clearance through cerebral microvascular, then reducing the level of Aβ deposition on cerebral microvascular wall, then reducing the level of senile plaques in brain parenchyma, so as to reduce the neurotoxicity of senile plaques, and improve the ability of learning and memory of APP/PS1 mice. |
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