Longitudinal study of in vivo bone mineral changes in rats using dual X-ray absorptiometry--effect of ovariectomy and prednisolone.

Longitudinal bone mineral measurement was performed by dual X-ray absorptiometry (DXA) in fifty 14-week-old Wistar rats divided into the following five groups: ovariectomized (OVX); sham-ovariectomized (SHAM); ovariectomized with release of proximal tail muscles (OVX + MR); prednisolone-administered (PDN); and saline-administered (control). Bone mineral density (BMD) was measured at the skull, distal femur, proximal tibia, and caudal vertebrae at 4, 8, 12, 16, 20, and 24 weeks after surgery or onset of administration. This in vivo DXA technique accurately showed correlation with the ash weight (r = 0.912-0.971), with a precision error of 1.01-2.05%. In the OVX group, the percent changes in distal femoral BMD and proximal tibial BMD were -7.6% and -5.3% at four weeks, followed by a gradual increase toward the initial value by 12 weeks. On the other hand, both OVX and SHAM rats gained BMD of the skull and caudal vertebrae. OVX+MR rats also gained BMD of the caudal vertebrae. Release of proximal tail muscles only had no significant effect on bone mineral of the caudal vertebrae. Prednisolone had no significant effect on bone mineral at any site.