Effect of 1alpha-vitamin D3 and estrogen therapy on cortical bone mechanical properties in the ovariectomized rat model.

Abstract

It is well documented that both bone mass and size of ovariectomized rats can be increased by 1alpha-vitamin D3 therapy. The repercussion of this therapy on bone mechanical competence is far less clear. Therefore, the objective of this study was to examine the mechanical properties of the shaft femur in ovariectomized rats (3 months old) receiving estrogen (0.25 mg/kg-week) and /or 1alpha-vitamin D3 (0.5 microgram/kg-day). The medication was given during 6 months starting immediately after ovariectomy or starting 3 months later. Torsional testing was performed from which the parameters strength, stiffness, maximum angular displacement, and energy-absorbing capacity (toughness) were derived. Multiple regression models were generated to estimate the relative importance of the therapies on bone mechanical properties. Bone stiffness increased with age. Ovariectomy improved bone mechanical parameters until 6 months postovariectomy, whereas estrogen treatment resulted in similar mechanical properties as those in intact age-matched controls. A significant improvement of all mechanical parameters was observed after 1alpha-vitamin D3 therapy. The combined therapy of 1alpha-vitamin D3 and estrogen was less effective than 1alpha-vitamin D3 alone, but better than estrogen therapy alone, suggesting interactive effects between both therapies. We conclude that 1alpha-vitamin D3 treatment of ovariectomized rats improves bone mechanical competence, which might be partially related to alterations in both bone mass and size.

Vitamin D Therapy of Osteoporosis: Plain Vitamin D Therapy Versus Active Vitamin D Analog (D-Hormone) Therapy

“…Additionally, it appears that the active analog therapy may correct mild osteomalacia associated with aging-associated vitamin D deficiency and may promote micro-callus formation and bone fracture healing. This in turn may improve the bone quality, as has been demonstrated in animal models [91].…”

Experimental osteoporosis induced by ovariectomy and vitamin D deficiency does not markedly affect fracture healing in rats

“…Increased mechanical load has been reported to promote fracture healing and callus formation in mice (Gardner et al 2006), and since body weight is proportional to the load applied to the callus in vivo, normalization of callus strength by body weight was an important correction, but did not alter the statistical outcome. Although OVX-related weight gain in rats is mainly caused by excess adipose tissue rather than increased/maintained bone mass (Gray and Wade 1981, Wade and Heller 1993, Sato et al 1994, OVX has been reported to stimulate periosteal appositional growth at the long bone diaphysis (Turner et al 1987, Miller et al 1991 while at the same time increasing bone resorption at endosteal surfaces, leading to expansion of the medullar cavity (Turner et al 1987, Jee et al 1990, Peng et al 1994, Pan et al 1995, Aerssens et al 1996. Since the bone resorbed at the endosteal surface close to the bone marrow is replaced at the periosteal adjacent surface, enlargement of the medullar cavity and cortical thinning may Ovx-D 6 29.5 (1.5) 6 29.3 (1.9) 6 5.9 (0.2) 6 6.0 (0.2) 6 43.6 (2.4) 6 46.2 (5.0) Sham 5 29.4 (1.5) 5 28.9 (1.4) 5 5.9 (0.5) 5 5.7 (0.3) 5 45.6 (4.3) 4 41.7 (2.7) a n is the number of animals studied b Significant differences (p = 0.01) with respect to Ovx-D c Significant differences (p = 0.02) with respect to Ovx-D d Significant differences (p = 0.03) with respect to Ovx-D Acta Orthop Downloaded from informahealthcare.com by Gazi Univ.…”

Transplantation osteoporosis and corticosteroid-induced osteoporosis in autoimmune diseases: experience with alfacalcidol

“…In these fundamental studies we found that alfacalcidol has a profound protective and curative effect not only on bone mass but also on bone quality tested by mechanical testing, namely torsional loading test of whole bones. The combination of alfacalcidol with estrogens was less effective than alfacalcidol alone, but more effective than estrogens alone (8).…”