Ovariectomy decreases osteogenetic activity in rat bone.

The purpose of this study was to investigate the effect of ovariectomy on osteoinductive activity in the bone in rat. Homograft implantation of decalcified humeral diaphysis from ovariectomized or sham-operated rats was performed and harvested after several time periods. A significant decrease in bone induction was found in terms of soft X-ray photography, alkaline phosphatase activity, mineral content and expression of osteocalcin (BGP; bone gla-protein) in the implants from the ovariectomized group in comparison to those from the sham-operated animals. This result suggested that the level of osteoinductive activity, probably due to bone morphogenetic protein, decreased in ovariectomized animals.