Region-specific effects of blocking estrogen receptors on longitudinal bone growth.

Estrogen receptors (ERs) regulate the development of the growth plate (GP) by binding to estrogen, a phenomenon that determines the growth of skeletal bone. However, the exact mechanisms underlying the regulatory effects of ERs on axi al and appendicular growth plates during puberty remain unclear. In the present study, the strategy of ERß blocking resulted in increased longitudinal elongation of the appendicular bone (P < 0.01), whereas ERa blocking suppressed appendicular elongation (P < 0.05). Blocking both ERs did not have opposite effects on axial longitudinal gro wth. The expression of chondrocyte proliferation genes including collagen II, aggrecan, and Sox9 and hypertrophic marker genes including collagen X, MMP13, and Runx 2 was significantly increased in the growth plate of female mice treated with ERß antagonist compared with that in the GP of control mice (P < 0.05). There were no significant differences in local insulin-like growth factor 1 (IGF-1) expression among these groups (P > 0.05), and Indian hedgehog protein (Ihh) and parathyroid-related protein (PTHrP) expressions differed among these groups (P < 0.05). ERs appeared not to affect axial bone growth during puberty in female mice (P > 0.05). Our data show that the blocking of different ER subtypes might have a region-specific influence on longitudinal a ppendicular and axial growth. [ABSTRACT FROM AUTHOR]