Study On Effects Of Genistein To Prevent Osteoporosis In Ovariectomized Rats And Its Mechanism

The purpose of this study was to investigate the effects of genistein in protecting against osteoporosis and involved mechanism in ovariectomized rats and cultured osteoblast from neonatal rat calvaria.The results showed that ovariectomy decreased both bone mineral density and the bone ultimate stress. The trabecular bone volume also decreased significantly. The mean trabecular plate thickness became thinner. Ovariectomy not only increased mean trabecular plate space and mean osteoid width, but also prolonged mineralization lag time and osteoid maturation period. In ovariectomized rats, the bone concentrations of Ca, P, Zn, Mn and Mg were lower, but the serum concentration of osteocalcin and urine excretory amounts of deoxypyridinoline and hydroxyproline were higher. Ovariectomy reduced the serum estrogen and calcitonin concentrations, however it did not affect serum parathyroid content.After three months of genistein supplementation to ovariectomized rats, bone mineral density and bone ultimate stress induced by ovariectomy increased. And trabecular bone volume, bone mineralization lag time and urine deoxypyridinoline were improved signifcantly. However, bone Zn, Mn and serum estrogen and parathyroid were not affected.Osteoblast was cultured for 72h in the presence of different doses of genistein. Data indicated that genistein significantly increased optical density of MTT and activity of ALP and also promoted 3H-TdR as well as 3H-pro incorporation into osteoblast. However, it did not affect the expressions of estrogen receptor and its mRNA, c-fos, c-jun, and TGF- and IL-6 cytokines.The above mentioned results suggest that supplement of genistein to ovariectomized rats can improve bone mineral density and the bone biomechanical properties, increase bone reflexity, promote the mineralization of bone, and reverse the loss of bone in ovariectomized rats. Furthermore, genistein can elevate the level of serum calcitonin, reduce the activity of osteoclast and attenuate the loss of Ca and P in bone. Besides, it can promote the synthesis of osteoblast DNA and collagen and improve the proliferation and differentiation of osteoblast which may be one of the mechanisms to protect against osteoporosis. However, more details of how genistein facilitate the proliferation and differentiation of osteoblast need to be studied further.