| Objective To study the effect of estrogen on bone mineral density and bone metabolism in osteoporotic rats. Methods 48 female SD rats were randomly divided into control group (sham operation group), model group, estrogen group and estrogen combined with tamoxifen group, with 12 in each group. All groups were ovariectomized except for the control group. Rats in the estrogen group were given nilestriol (1 mg/kg) once per week, rats in the estrogen combined with tamoxifen group were given nilestriol (1 mg/kg) and tamoxifen (3 mg/kg) once per week, and the model and control groups were given the same amount of saline lavage. After 3 months, bone mineral density (BMD) and content of bone mineral salt of the left femur, serum calcium and tibia bone calcium were assessed. ALP and TRAP-5b levels were detected using ELISA method. Protein expression levels of OPG and RANKL were measured using IHC-P method. Results Before therapy, serum calcium and the level of TRAP-5b in the model group, estrogen group and estrogen combined with tamoxifen group were significantly higher than that in the control group (P<0.05), and bone calcium, BMD and the content of bone mineral salt were significantly lower (P<0.05), while the serum content of ALP was not significantly different (P>0.05). After treatment, the levels of serum calcium, TRAP-5b and RANKL expression in the estrogen group were significantly decreased compared with the model group (P<0.05), and the level of bone calcium, ALP, OPG, BMD and the content of bone mineral salt were significantly higher in the estrogen group compared with the model group (P<0.05). However, after therapy, there were no significant differences between the estrogen combined with tamoxifen group and the model group. Conclusion Estrogen can treat osteoporosis by significantly improving bone mass and inhibiting osteoclast activities. |