ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P64

Daidzein unlike other isolated isoflavones, preserves bone architecture in ovariectomized female rats in vivo

Dalia Somjen1, Sara Katzburg1, Fortune Kohen2, Batya Gayer2 & Erella Livne3

1Institute of Endocrinology, Metabolism and Hypertension, Tel-Aviv Sourasky Medical Center and the Sackler Faculty of Medicine, Tel-AvivUniversity, Tel-Aviv 64239, Israel; 2Department of Biological Regulation, The Weizmann Institute, Rehovot 76100, Israel; 3Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.

Ovariectomy of immature female rats, results in significant decrease of trabecular bone volume and in cortical bone thickness. Previously we found that estradiol-17β (E2) restored bone structure of ovariectomized female rats (Ovx) to values obtained in intact sham-operated female rats. E2 also selectively stimulated creatine kinase specific activity (CK) a hormonal-genomic activity marker. In the present study, we compared the effects of E2 and the phytoestrogens: daidzein (D), biochainin A (BA), genistein (G), carboxy-derivative of BA (cBA) and the SERM raloxifene (Ral) in Ovx, on both histological changes of bones and CK, when administered in multiple daily injections for 2.5 months. Bone from Ovx rats, showed significant disrupted architecture of the growth plate, with fewer proliferative cells and less chondroblasts. The metaphysis underneath the growth plate, contained less trabeculae but a significant increased number of adipocytes in the bone marrow. D like E2 and Ral but not G, BA or cBA, restored the morphology of the tibiae, similar to that of control sham-operated animals; the bony trabeculeae observed in the primary spongiosa was thicker, with almost no adipocytes in bone marrow. Ovariectomy resulted also in reduced CK, which in both epiphysis and diaphysis was stimulated by all estrogenic compounds tested. In summary, only D stimulated skeletal tissues growth and differentiation as effectively as E2 or Ral, suggesting that under our experimental conditions, D is more effective in reversing menopausal changes than any of the other isolated phytoestrogens which cannot be considered as one entity.

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