Moreover, these findings suggested that the up-regulation of SIRT1 induced by 17β-E2 has the potential to protect against osteoporosis, and that the beneficial effect of SIRT1 depend, at least in part, on promoting osteoblasts autophagy via AMPK-mTOR pathway and inhibiting cell apoptosis via FOXO3a activation. Here, SIRT1 is linked to osteoporosis.