Figure 4.

Induction of bone formation in ovariectomized rats by 2MD in vivo. Retired breeders received from Harlan–Sprague–Dawley were sham-operated or ovariectomized. The rats were fed a 0.47% calcium, 0.3% phosphorus diet supplemented with vitamins A, D, E, and K as described by Suda et al. (8), which provides 75 units (3 μg) of vitamin D₂/week per animal. Before ovariectomy, the individual BMD were assessed by using dual photon absorptiometry (DPXα General Electric, Lunar). Five weeks after the initial BMD readings were made, oral administration of either 2MD or 1,25(OH)₂D₃ (6) in 0.1 ml of Wesson oil was initiated at the doses and frequencies indicated. Ovariectomized and sham-operated control animals received 0.1 ml of Wesson oil. (a) Serum calcium levels were determined by atomic absorption spectrometry at the indicated times for vehicle-treated sham-operated rats and ovariectomized rats treated with vehicle, 2MD, or 1,25(OH)₂D₃ at the indicated dose. (b) Total body bone mass was assessed in each group at 13 weeks and again at 23 weeks as above. *, Significance at P < 0.001.