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. Author manuscript; available in PMC: 2015 Jul 1.
Published in final edited form as: J Steroid Biochem Mol Biol. 2013 Oct 29;142:155–170. doi: 10.1016/j.jsbmb.2013.09.008

Figure 1.

Figure 1

Cellular changes that occur with estrogen changes. + E depicts effects in presence of estrogen; -E depicts effects in absence of estrogen. IL-1 is Interleukin 1, TNF-Tumor Necrosis Factor, OPG-Osteoprotegerin. Estrogen decreases osteoclastogenesis and increases osteoclast apoptosis. Estrogen reduces osteoclastogenesis by suppressing IL-1 and TNF and increasing the sensitivity of stromal cells/preosteoblasts to IL-1, thus suppressing MCSF, RANKL, and perhaps most notably, IL-6. In addition, estrogen stimulates the production of OPG, the potent inhibitor of osteoclastogenesis. Estrogen also reduces the responsiveness of osteoclast precursors to RANKL. Estrogen also promotes osteoclastic apoptosis, thereby reducing osteoclast lifespan. This effect appears to be mediated by TGFβ.