Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.
J Nutr. 2010 Apr;140(4):766-72. doi: 10.3945/jn.109.116343. Epub 2010 Feb 17.
Neonatal exposure to soy isoflavones at levels similar to that of infants fed soy protein formula resulted in higher bone mineral density (BMD), improved bone structure, and greater bone strength at young adulthood in female CD-1 mice (1,2). Our objective in this study was to determine whether these improvements in bone quantity and quality at 4 mo of age provide protection against the deterioration of bone tissue that occurs after a decline in endogenous sex steroid production. Male and female CD-1 mice (n = 8-18 pups per group per gender) were randomized to subcutaneous injections of corn oil [negative control (CON)], daidzein + genistein (DG; 7 mg x kg body weight(-1) x d(-1)), or diethylstilbestrol [(DES); positive control, 2 mg x kg body weight(-1) x d(-1)) from postnatal d 1 to 5. At 4 mo of age, mice were ovariectomized (females) or orchidectomized (males) and studied to 8 mo of age. Females treated with DG had higher (P < 0.05) femur and vertebral bone mineral content (BMC) and BMD compared with the CON group. Microstructural analysis revealed that improvements in BMD induced by DG and DES were coupled with greater trabecular thickness at the lumbar spine. Importantly, structural improvements resulted in bones that were more resistant to fracture, as the peak load of the femoral midpoint and lumbar vertebra 2 were higher (P < 0.05) with DG compared with CON. Effects in males were not significant. In conclusion, short-term neonatal exposure to isoflavones provides protection against the deterioration of bone tissue in females but not males after a decline of endogenous sex steroid production.
新生雌性 CD-1 小鼠经口摄入与配方奶粉中大豆蛋白等水平的大豆异黄酮，可导致其在幼年期时骨密度（BMD）更高、骨结构改善、骨强度更大（1,2）。本研究的目的是确定 4 月龄时这些骨量和骨质量的改善是否能预防内源性性激素产生下降后骨组织的恶化。雄性和雌性 CD-1 小鼠（每组每性别 8-18 只幼鼠）随机接受皮下注射玉米油（阴性对照[CON]）、大豆苷元+染料木黄酮（DG；7mgxkg 体重(-1)xd(-1)）或己烯雌酚（DES；阳性对照，2mgxkg 体重(-1)xd(-1)），从产后第 1 天至第 5 天。4 月龄时，对小鼠进行卵巢切除术（雌性）或睾丸切除术（雄性），并研究至 8 月龄。与 CON 组相比，DG 处理的雌性小鼠股骨和椎体骨矿物质含量（BMC）和 BMD 更高（P<0.05）。微观结构分析表明，DG 和 DES 诱导的 BMD 改善与腰椎小梁厚度增加有关。重要的是，结构的改善使骨骼更能抵抗骨折，因为与 CON 相比，DG 组的股骨中点和腰椎 2 的峰值负荷更高（P<0.05）。雄性的作用不显著。总之，新生期短期接触异黄酮可预防内源性性激素产生下降后雌性而非雄性骨组织的恶化。
