Effect of 1 alpha-hydroxyvitamin D3 on osteoporosis induced by immobilization combined with ovariectomy in rats.

The effect of low-dose 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] on experimental osteoporosis in rats induced by a combination of hemicordotomy and ovariectomy was evaluated. 1 alpha(OH)D3 (0.1 microgram/kg 1 alpha(OH)D3 three times a week) increased the femur score and photo-density. The administration of 1 alpha(OH)D3 also significantly increased the dry weight and ash weight of the bone. Histomorphometry revealed a significant decrease of bone resorption by the administration of 1 alpha(OH)D3. Significant decreases in 45Ca accretion rate and 14C-proline uptake were also observed. Bone formation in the 1 alpha(OH)D3 treated group was thought to decrease following the decrease of bone resorption.