EFFECT OF OVARIECTOMY ON INTRAOSSEOUS VASCULARIZATION AND BONE REMODELING IN RATS - ACTION OF TILUDRONATE

In order to study the action of tiludronate on the changes in intraoss eous vascularization induced by ovariectomy, and to link these effects to those observed in bone remodelling, 30 female Sprague-Dawley rats (age 40 weeks) were studied. Ten rats were sham-operated and treated b y vehicle, 10 rats were ovariectomized and treated by vehicle, and 10 rats were ovariectomized and treated orally with tiludronate, 0.16 mmo l/kg/per day, 3 days a week for 16 weeks, from the day following ovari ectomy. The rats were killed after 4 months, and a histomorphometric s tudy and quantification of intraosseous vessels carried out on the six th lumbar vertebra. The area of the intraosseous sinusoidal capillarie s increased after ovariectomy, which also induced a moderate increase in resorption surfaces and osteoid surfaces leading to a decrease of 4 0% in the trabecular bone volume at the lumbar spine level. This bone mineral loss was completely prevented by tiludronate, which normalized the bone turnover. However, tiludronate was without any effect on int raosseous vascularization. These results indicate that the surface are a of the intraosseous sinusoidal capillaries was correlated positively with resorption surfaces and negatively with trabecular bone volume a nd the number of bone trabeculae. In these experimental conditions, an inhibitor of bone resorption can exert its positive effect on bone ma ss without normalization of vascularization.