Fig. 9.

GA-inhibited Hsp90 protective pathways in Aβ-induced neuronal toxicity and long-term memory impairment. GA-induced Hsp90 inhibition leads to HSF-1 release that subsequently transactivates Hsps, such as Hsp70 and Hsp90. Upregulated Hsp70 have the potential to counter Aβ-induced oxidative stress by several antioxidative mechanisms that ultimately reduce Aβ-induce apoptosis. GA also activates p70s6k, a key factor in mTOR signaling pathway, which results in long-term memory improvement, disrupted by exogenous Aβ. P70s6k activation also reduces neuronal apoptosis by activation of autophagy, reduction of oxidative stress and the activation of antiapoptotic agents, such as Bcl-2