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[Effects of alfacalcidol on osteoporosis in ovariectomized rats]
1Department of Endocrinology, Peking Union Medical College Hospital, PUMC & CAMS, Beijing, 100730, China.
Objective:
To investigate the effects of alfacalcidol on osteoporosis in rats induced by ovariectomy (OVX).
Methods:
Fifty-three virgin female Wistar rats of six months old were divided into 6 groups: (1) rats in baseline group (base) were sacrificed what 6 months before OVX, and those in the other 5 groups were either bilaterally OVX or sham-operated (sham) as follows: (2) Sham; (3) OVX baseline (OVXb); (4) OVX end (OVXe); (5) OVX + 17beta-estradiol 20 microgram/kg.(-1) SC. (O + E); and (6) OVX + alfacalcidol 0.1 microgram/kg.(-1) oral (O + VD). Rats in OVXb group were sacrificed 6 weeks after OVX and the others were sacrificed 14 weeks after surgery. Alfacalcidol (TEVA, Israel) was fed orally at 6 weeks after OVX and lasted for 8 weeks. Urine and serum samples were collected before sacrifice to determine the bone turnover markers. The right tibia was processed undecalcified for histomorphometric analysis, and the right femur was prepared for pQCT scanning and bone biomechanical measurement with indentation test.
Results:
Treatment of OVX rats with alfacalcidol (O + VD) increased tibial cancellous bone volume in histomorphometric analysis (12.0% +/- 1.1% vs 5.8% +/- 1.3%, P < 0.01). pQCT scanning showed that trabecular BMC and BMD were sharply elevated in O + VD group compared with OVXe group, increased 109.2% and 133.1% respectively (P < 0.01). In consistency with these changes in mechanical competency of cancellous bone in distal femur, maximal load was enhanced in O + VD group compared with OVXe group (21.3% +/- 4.0% N vs 7.9% +/- 1.9% N, P < 0.05). All these changes in O + VD group were similar to those in 17beta-estradiol treatment group (O + E). Serum calcium concentration increased in O + VD group. Histomorphometric and biochemical indices of bone resorption reduced in O + VD group.
Conclusion:
Alfacalcidol effectively prevent bone loss in OVX rats and restore partly the trabecula, with evidenced increasing density, contents as well as maximal loads of cancellous bone, and reduce bone resorption.