The Effect Of The Replacement Therapy By Estrogen On The Bone Metabolism

Purpose:To explore effect of estrogen replacement therapy on bonemetabolism.Methods:After being performed ovariectomy, 24 SD rats which were 12 months old(provided by the animal center of JI NAN university) were divided randomly into 3 groups: Group I were administrated with sodium chloride injection one times a week with 1ml/100g. Group II were administrated with estrogen (nilestriol) one times a week with 0. 1mg/100g for 1 month. Group III were administrated with nilestriol one times a week with 0. Img/lOOg for 3 months . The blood from the rats' left ventricle was centrifugated to get the blood serum. The concentrations of serum alkaline phosphatase , serum calcium, serum phosphorus were detected by biochemistry methods. The average concentration of each kind of ion was compared with each other among the 3 groups. The bone mineral density (BMD) of the bones of limbs and vertebrae was detected by analysis meter of BMD. The average BMD was compaired with each other among the 3 groups. The cortex of bones of the limbs was detected by the X-ray study and compaired with each other. With the immunohistochemical method, the morphology and the numbers of immunoreactive positive cells of bone morphogenetic protein-2 (BMP-2) in the articular periosteum of limbs and on the surface of trabecula of limbs were observed and compared with each other among the 3 groups.Results:1.The concentration of serum calcium and serum phosphorus of group II and III were significantly decreased and the concentration of serum alkaline phosphatase of groupII and III were significantly increased than that of group I (P<0.05).2. The BMD of limbs and vertebrae of group II and III were increased significantly than that of group I ( P < 0.05 ) . The BMD of the vertebrae of group III were significiantly increased than group II (P< 0.05) .3. The cortex of the bones of the lower limbs of groupII and III were thicker than that of group I .4. The BMP-2 immunoreactive positive granule are found to distribute the osteoblasts and osteoprogenitor cells of the periosteam and osteoblasts on the surface of the trabecula. The positive cells on the surface of the trabecula of limbs and in the periosteum in the group II and III were stained more deeply than that of group I , the numbers of positive cells in group II and III were also significantly increased than those of group I (P<0. 05) .Conclusion:The estrogen can obviously effect on the bone metabolism and one of the mechanism of the estrogen replacement therapy on postmenopaus-al osteoporosis is that the estrogen probably promote the secretion of BMP-2 that contributes to the building of bone.