Fuzhisan ameliorates Aβ production and tau phosphorylation in hippocampal of 11 month old APP/PS1 transgenic mice: A Western blot study

Accumulation of amyloid-β (Aβ) peptide and deposition of hyperphosphorylated tau protein are two major pathological hallmarks of Alzheimer's disease (AD). Glycogen synthase kinase-3β (GSK3β) is increasingly thought to play a pivotal role in the pathogenesis of AD, both as a regulator of the production of Aβ and through its well-established role on tau phosphorylation. The phosphoinositide 3 kinase (PI3K)/Akt pathway plays an import role in neuronal survival and cognitive function, and is known as an upstream element of GSK3β. Fuzhisan (FZS), a Chinese herbal complex prescription, has been used for the treatment of AD for over 20 years, and is known to enhance the cognitive ability in AD patients as well as in AD model rats. However, it still remains unclear whether FZS is responsible for regulation of PI3K/AKT/GSK3β signaling and contributes to subsequent down-regulation of Aβ and phosphorylated tau. Thus, we treated APP/PS1 transgenic mice, a useful model of AD-related memory impairment, with FZS by intragastrical administration for 60 days and Donepezil was used as a positive control. The results showed that treatment with FZS significantly reversed the memory deficit in the Tg APP/PS1 mice in the Morris water maze test. Moreover, FZS significantly attenuated Aβ production through inhibition of APP procession and phosphorylation of tau in the hippocampus of Tg APP/PS1 mice. In addition, FZS treatment also increased PI3K and pSer473-AKT levels, inhibited GSK3β activity by increasing phosphorylation of GSK3β at Ser9. These results indicated that the memory ameliorating effect of FZS may be, in part, by regulation the PI3K/AKT/GSK3β signaling which may contribute to down-regulation of Aβ and tau hyperphosphorylation.