Effects of Raloxifene Co-Administration on Bone Histomorphometric
Changes in Rats Treated with GnRHa

Petek BALKANLI-KAPLAN, H. Alper BAĞRIYANIK, Fatih GÜCER, Tunç CANDA, Osman YILMAZ, M. Ali YÜCE
Edirne-Turkey

OBJECTIVE: This study was carried out to show the changes in bone structure by histomorphometric analysis in rats administered GnRHa and to evaluate the effectiveness of raloxifene to revert bone changes related to analog administration.
STUDY DESIGN: Three months of female rats were divided into three groups. Group 2 and 3 were subcutaneously administered of leuprolin acetate, while group 1 was administered saline solution every 4 weeks. GnRHa therapy lasted 16 weeks, and raloxifene, as an add-back agent, were given at 8 weeks of treatment in group 3, meanwhile other groups were administered oral saline solution. At the end of the forth month, right tibia bone histomorphometric analysis were done in the three groups.
RESULTS: Bone histomorphometric examination showed that GnRHa administration decreased bone volume (20.8±7.3% vs. 17.3±3%), trabecular thickness (55±4 mm vs. 49.4±10.7 mm) and cortical thickness (290.6±26 mm vs. 261.9±35.6 mm). Concurrent treatment with raloxifene attenuated all of the changes in bone histomorphometric parameters found in GnRHa-treated rats. Administration of raloxifene also reduced bone turnover despite the significantly increasing bone volume and osteoblast surface compared with GnRHa-alone treatment (29.5±5.9% vs. 17.3±3%, 6.7±1.2% vs. 4.2±1%, P<0.01, respectively).
CONCLUSION: These results imply that during long-term GnRHa treatment concurrent administration of raloxifene might be useful for protection of both trabecular and cortical bone loss.
(Gynecol Obstet Reprod Med 2005; 11:99-102)

Key Words: Bone loss, GnRHa, Raloxifene, Bone Histomorphometry