| Alzheimer’s disease(AD) is degenerative disease of the central nervous system, cognitive dysfunction and recognization recession as main clinical feature. It is mainly neuropathlogically characterized by the deposition of extracellular β-amyloid (AP) plaques and intracellular neurofibrillary tangle. Aβ-peptides contain 39-42 amino acids, which are derived from the amyloid precursor protein (APP) cleaved by β--secretases and y-secretases in the amyloidogenic pathway. The cracking procession of APP includ two pathway:1)non-amyloid pathway:APP is cleaved byα-secretases and y-secretases; 2) amyloid pathway:APP is cleaved by β--secretases and y-secretases. Ample evidence exist to prove that Aβ plaques which can induce inflammation and oxidation, are toxic to neurons, leading to apoptosis and necrosis.Recent studies show that cholinesterase inhibitors are the main drugs treatment for AD. But their role are limited, and some of these have certain side effects. There are three types of Chinese herbs which are astragalosides (AST), gastrodin (GAS), and paeoniflorin (PAE) which are choosed for studying AD. These have reported that these Chinese herbs have many effects including antioxidation, improving ability of memory,protecting neuron and so on.But it is not clear that they can move Aβ plaques and ameliorate the symptom of AD. So we study effects of these types of Chinese herbs to AD mice model and AD cell model, and the mechnisms of these herbs.Firstly, to investigate the effect of gastrodin(GAS), Astragaloside(AST) and Paeoniflorin (PAE) from three types of traditional Chinese herbs against P-amyloid plaques in 5XFAD Alzheimer’s disease (AD) transgenic mice,5×FAD mice were randomly divided into six groups, including GAS-high dose group (GAS-H,300 mg/kg/d),GAS-low dose group (GAS-L,150 mg/kg/d),AST-high dose group (AST-H, 160mg/kg/d), AST-low dose group (AST-L,80mg/kg/d), PAE-high dose group(PAE-H,60mg/kg/d) and PAE-low dose group(PAE-H,30mg/kg/d). Meanwhile, the transgenic positive group and negative control group were setup. After being treated for four months,5×FAD mice were evaluated by Morris water maze for memory ability and by ELISA for Aβ in the cerebral homogenate. Then, Aβ plaques in the hippocampus and cortex of 5×FAD mice were observed and analyzed with Immunohistochemical staining. In additional, mice in every group were tested the effects of body weight,and underlying liver and kidney side effects. The results show that GAS、 AST and PAE can reverse the learning and memory ability of 5XFAD mice, and reduce Aβ in the cerebral homogenate and Aβ plaques in brain. Compared with the untreated transgenic positive group, Aβ plaques were declined in hippocampus and cortex of GAS-H group by 70.13% and 80.96%(P< 0.01), of AST-H group by 62.39% and 69.57%,(P< 0.01) of PAE-H group by 57.58% and 66.62%(P< 0.01). A β was reduced in the cerebral homogenate of each group. The effects show dose-independent. Besides, the results show that GAS、 AST and PAE have no effects to body weight of mice, and the levels of AST,GPT and Crea show they have nontoxic to liver and kidneySencondly, we utilize cell models including 117 cell (over-expression A(3 and β-secretase) and 146 cell (over-expression Aβ andy-secretase) to explore the underlying mechanism. After being treated different Chinese herbs,extracelluar and intracellular Aβ were determined by ELISA, and, BACE (β-secretase site APP cleaving enzyme) and PS1 (γ-secretase site APP cleaving enzyme) expression were analyzed with Q-PCR and Western blotting. The results show that in vitro study suggests a dose-dependent effect of GAS, AST and PAE in reducing A β in 117 cell model and 146 cell model. Extracelluar Aβ of 117 cells with three herbs(GAS,AST and PAE) were respectively reduced by 65.8%、67.8% and 25.2%. Ixtracelluar Aβ of 117 cells with three herbs were respectively reduced by 69.2%、64.8%and 47.9% (P<0.01). Extracelluar Aβ of 146 cells with three herbs were respectively reduced by 67.1%、65.4% and 50.9%(P<0.01). Intracelluar Aβ of 146 cells with three herbs were respectively reduced by 67.9%、82.6% and 49.9%(P<0.01). At 100μmol·L-GAS,BACE expression was largely supressed in mRNA by 32.9%(P< 0.01), At 50 μmol·L-1 GAS, the protein level was declined by 47.9%(P< 0.01).In conclusion, three types of Chinese herbs including GAS,AST and PAE can improve the ability of memory and cognition, and the effects show dose-independent; GAS,AST and PAE can inhibit β-amyloid plaques in hippocampus and cortex of AD mice, and they can decrease the level of β-amyloid in brain of AD mice;three types of Chinese herbs have been shown non-toxic to AD mice. Meanwhile, GAS,AST and PAE can reduce the levels of β-amyloid of 117 cells and 146 cells. GAS can inhibit the transcription levels of BACE mRNA and the protein level of β-secretase.So we predict that GAS decreases β-amyloid by inhibiting β-secretase, and we have not detected that AST and PAE have effects to β-secretase or y-secretase. |
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