Estrogen, Soy Isoflavones On Ovariectomized Rat Bone Metabolism

【Objective】To study the effect of soybean isoflavones on the bone metabolism ovariectomized rats.【Methods】Twenty-eight 10-week-old female Sprague-Dawley(SD) rats were randomly assigned to the following four experimental groups:1.Sham-operate group(SHAM) 2.Ovariectomized group(OVX) 3.Ovariectomized added soybean isoflavones group (OVX+ISO) Ovariectomized and fed orally soybean isoflavones using a stomach tube (100mg/kg/d) 4.Ovariectomized added estradiol(OVX+E) Ovariectomized and intramuscularly injected with estradiol benzoate(0.1mg/kg once a week ).Rats of the SHAM group only underwent the resection of a bit fat.The rest groups all underwent the resection of bilateral ovaries and fed physiological salinc(NS) on a equal lever with soybean isoflavones. The time of experiment is 12 week.Then all the rats were killed by bloodletting of femoral artery to examine the activities of serum total alkaline phosphatase(ALP),bone alkaline phosphatase (B-ALP) and tartrate resistant acid phosphatase(TRACP).To examine urine calcium, phosphorus compared with creatinine and pyridinoline(Pyd) lever in rats.Separating the right femur of all the rats to examine the mineral density(BMD) and the calcium content of the bone.Results:Rats in the OVX group had significantly lower calcium and phosphorus content and mineral density of the bone(BMD)(P＜0.05),and higher serum calcium lever(P＜0.05),and higher urine calcium and phosphorus compared with creatinine and pyridinoline(Pyd) lever in rats than those in other groups(P＜0.05).And serum calcium and urinary excretion of calcium and pyridinoline(Pyd) lever had significantly lower in OVX+ISO,OVX+E groups(P＜0.05),and higher the mineral density(BMD) and the calcium content of the bone in OVX+ISO,OVX+E groups(P＜0.05).The activities of ALP,B-ALP,TRACP and the IL-6 content of the serum in OVX group had significantly higher(P＜0.05).And all had lower in OVX+ISO,OVX+E groups (P＜0.05).【Conclusion】Soybean isoflavones can inhibit the bone loss of ovariectomized rats,and enhance calcium absorption,and decrease bone metabolism.These results indicate that soybean isoflavones exhibits estrogenic action.