Effects of genistein aglycone in osteoporotic, ovariectomized rats: a comparison with alendronate, raloxifene and oestradiol

Background and purpose: Genistein aglycone positively affects bone loss in postmenopausal women, but bone quality data are still lacking. To clarify this, we investigated the effects of genistein compared with alendronate, raloxifene and oestradiol in an animal model of established osteoporosis. Experimental approach: Six months after ovariectomy, 96 ovariectomized (OVX) rats were divided into 8 equal groups, randomized to treatments (genistein aglycone (1 and 10mgkg(-1) s.c.); alendronate (0.003 and 0.03mgkg(-1) s.c.); raloxifene hydrochloride (0.05 and 0.5mgkg(-1) s.c.); 17-alpha-ethinyl oestradiol (0.003 and 0.03mgkg(-1) s.c.)) for 12 weeks. Untreated OVX (n = 12) and sham OVX (n = 12) were used as controls. At the beginning and end of treatment, bone mineral density (BMD) and bone mineral content (BMC) were assessed. At the end of the experiment, calcium, phosphorus, bone-alkaline phosphatase (b-ALP), collagen C-telopeptide (CTX), osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-kappa B ligand (sRANKL) were assayed. Femurs were removed and tested for breaking strength and histology. Key results: Genistein (10mgkg(-1)) showed a greater increase in both BMD (P < 0.0001 vs OVX) and BMC than all the other treatments. Moreover, genistein significantly increased breaking strength, bone quality, b-ALP (P < 0.0001 vs OVX) and OPG, and reduced CTX and sRANKL compared with the other treatments at all dose levels. Conclusions and implications: The results strongly suggest that the genistein aglycone might be a new therapy for the management of postmenopausal osteoporosis in humans.