Impact of 4-methylbenzylidene camphor, daidzein, and estrogen on intact and osteotomized bone in osteopenic rats

The study investigated the influence of 4-methylbenzylidene camphor (4-MBC), daidzein, and estradiol-17 beta-benzoate (E-2) on either intact or osteotomized cancellous bone in ovariectomized (Ovx) rats. Three-month old Ovx rats were fed with soy-free (SF) diet over 8 weeks; thereafter, bilateral transverse metaphyseal osteotomy of tibia was performed and rats were divided into groups: rats fed with SF diet and SF diet supplemented with 4-MBC (200 mg), daidzein (50 mg), or E-2 (0.4 mg) per kilogram body weight. After 5 or 10 weeks, computed tomographical, biomechanical, histological, and ashing analyses were performed in lumbar spine and tibia of 12 rats from each group. 4-MBC and E-2 improved bone parameters in lumbar spine and tibia, were not favorable for osteotomy healing, and decreased serum osteocalcin level. However, daidzein improved bone parameters to a lesser extent and facilitated osteotomy healing. For lumbar spine, the bone mineral density was 338 +/- 9, 346G5, 361 +/- 6, and 360 +/- 5 mg/cm(3) in SF, daidzein, 4-MBC, and E-2, respectively, after 10 weeks. For tibia, the yield load was 98 +/- 5, 114 +/- 3, 90 +/- 2, and 52 +/- 4 N in SF, daidzein, 4-MBC, and E-2, respectively, after 10 weeks. Serum daidzein was 54 +/- 6 ng/ml in daidzein group and equol was not detected. Alp and Igf1 genes were down-regulated in callus after daidzein and E-2 compared with 4-MBC (week 5). The response of bone tissue and serum markers of bone metabolism could be ordered: daidzein<4-MBC