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Keywords:

  • Alzheimer's disease;
  • amyloid;
  • Akt;
  • tau proteins;
  • glycogen synthase

Abstract

Increasing evidence has shown that β-amyloid (Aβ) induces hyperphosphorylation of tau and contributes to Aβ toxicity. Recently, tau hyperphosphorylation by glycogen synthase kinase-3β (GSK-3β) activation has been emphasized as one of the pathogenic mechanisms of Alzheimer's disease (AD). The phosphoinositide 3 kinase (PI3K)/Akt pathway is known as an upstream element of GSK-3β. The inhibitory control of GSK-3β, via the PI3K/Akt pathway, is an important mechanism of cell survival. In the present study, we investigated the neuroprotective effects of Angelica sinensis (AS), a traditional Chinese herbal medicine, against Aβ1–42 toxicity in cultured cortical neurons and also the potential involvement of PI3K/Akt/GSK-3β signal pathway. We revealed that AS extract significantly attenuated Aβ1–42-induced neurotoxicity and tau hyperphosphorylation at multiple AD-related sites in a dose-dependent manner. Simultaneously, it increased the levels of phospho-Ser473-Akt and down-regulated GSK-3β activity by PI3K activation. The neuroprotective effects of AS extract against Aβ1–42-induced neurotoxicity and tau hyperphosphorylation were blocked by LY294002 (10 μM), a PI3K inhibitor. In addition, AS extract reversed the Aβ1–42-induced decrease in phosphorylation cyclic AMP response element binding protein (CREB), which could be blocked by the PI3K inhibitor. These results suggest that AS-mediated neuroprotection against Aβ toxicity is likely mediated by the PI3K/Akt/GSK-3β signal pathway. © 2010 Wiley-Liss, Inc.