BONE-DENSITY IS NORMAL IN MALE-RATS TREATED WITH FINASTERIDE

Bone is an androgen-dependent tissue. It is not known whether normal b ony growth and mineralization in males is dependent on testosterone al one, or whether its metabolite, dihydrotestosterone (DHT), also is req uired. To answer this question, we examined the effect of finasteride, an inhibitor of DHT synthesis, on bone in rats. Three-month-old male rats were treated with placebo, finasteride, or orchidectomy. The bone mineral densities (BMD) of the spine and whole body were measured in vivo by dual x-ray absorptiometry at weeks 0 and 11, and the BMD of th e femur and tibia were measured ex vivo at week 11. Histomorphometric analysis was performed on the proximal tibia at week 11. The increase in spine and whole body BMD in finasteride-treated rats did not differ from that in controls, whereas these values were significantly lower in orchidectomized rats. Similarly, the BMD of the femur and tibia and the cancellous bone volume of the proximal tibia in finasteride-treat ed rats did not differ from those in controls, whereas these values we re significantly lower in orchidectomized rats. In summary, bone devel opment and density were normal in rats treated with finasteride. We co nclude that selective DHT deficiency is not deleterious to the male ra t skeleton.