Prevention and treatment of osteopenia in the ovariectomized rat: effect of combined therapy with estrogens, 1-alpha vitamin D, and prednisolone.

The effects of estrogens and 1-alpha were studied in young animals after ovariectomy (OVX) and/or prednisolone (PDN). These medications were given separately or in combination as preventive therapy from the start of the experiment, and as curative therapy starting 3 months later. Changes in bone mass were evaluated by single photon absorptiometry of the femur at the diaphysis (containing mostly cortical bone) and at the distal end of the femur (containing mostly trabecular bone). Radiogrammetry was performed at 50% of the length of the femur. Estrogens prevented further bone loss after OVX and OVX + PDN, given either at the beginning of the experiment or started 3 months later, except for trabecular bone loss immediately after OVX + PDN. After 1-alpha vitamin D, a highly significant increase in BMC and BMD was found in controls, in animals treated with PDN, and after OVX and OVX + PDN. The combination of 1-alpha with estrogens was less effective than 1-alpha but more effective than estrogens alone. After correction for body weight changes globally the same results were found. We conclude that (1) estrogens prevent bone changes after ovariectomy and ovariectomy + prednisolone; and (2) 1-alpha vitamin D highly significantly increased bone mass in male and female rats, and after prednisolone treatment, ovariectomy, and ovariectomy + prednisolone treatment.