[Effect and mechanism of gastrodin inhibiting β-amyloid plaques in brain of mice].

This study was designed to investigate the effect of gastrodin（GAS） against β-amyloid plaques in 5×FAD Alzheimer’s disease（AD） transgenic mice, and utilize 117 cell model（over-expression of Aβ and β-secretase） to explore the underlying mechanism. 5×FAD mice model were randomly divided into three groups, including GAS-high dose group(GAS-H, 200 mg·kg(-1)·d(-1)), GAS-middle dose group(GAS-M, 100 mg·kg(-1)·d(-1)) and GAS-low dose group(GAS-L, 50 mg·kg(-1)·d(-1)). Meanwhile, the wild type mice were used in the control group. After being treated with GAS for three months, 5×FAD mice were evaluated by Morris water maze for the learning and 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. The cell apoptosis rate and the cell viability were determined in vitro, after the cells were treated with different concentrations of GAS(10, 25, 50 and 100 μmol·L(-1)). Furthermore, Intracelluar/extracelluar Aβ were determined by ELISA. Effects of GAS on BACE（β-secretase site APP cleaving enzyme） m RNA and protein expression were analyzed in 117 cell models by Q-PCR and Western blotting. The results suggest that GAS is able to restore the learning and memory capacity of 5×FAD mice, and reduce Aβ in the cerebral homogenate and Aβ plaques in the brain. Compared with the untreated transgenic positive group, Aβ plaques were declined in hippocampus and cortex of GAS-H group by 93.28% and 88.88%, and Aβ was reduced in the cerebral homogenate by 55.74%. In vitro study suggests a dose-dependent effect of GAS in reducing Aβ in 117 cell models. When the cells were treated with 100 μmol·L(-1) GAS, extracelluar Aβ and intracellular Aβ of 117 cells were reduced by 63.1% and 49.1%. BACE expression was largely suppressed in m RNA by 32.9%（P < 0.01）. At 50 μmol·L(-1) GAS, the protein level was declined by 47.9%（P < 0.05）. In conclusion, GAS inhibits Aβ production and accumulation by inhibiting β-secretase.