Effect of intraperitoneal injection of EphrinB2/EphB4-Fc protein fragment in ovariectomized osteoporotic rats
Objective To investigate the preventive and therapeutic effect of intraperitoneal injection of erythropoie-tin hepatocyte kinase receptor ligand B2(EphrinB2)/erythropoietin hepatocyte kinase receptor B4(EphB4)protein frag-ment on osteoporosis in ovariecto-mized mice.Methods Thirty-nine 7-week-old healthy female C57BL/6 mice were ran-domly divided into the sham operation group(n=13),model group(n=13)and intervention group(n=13).The menopaus-al model was established by removing the ovarian tissues of mice in the model group and intervention group,and only the adipose tissues around the ovarian tissues were removed in the sham operation group.One week after operation,mice in the intervention group were given intraperitoneal injection of EphrinB2-Fc protein fragment and EphB4-Fc protein fragment 0.1 mg/(kg·d),while mice in the sham operation group and model group were injected with the same amount of normal sa-line,and continued to be fed for 16 weeks.The mice were killed and the femur was removed,the mechanical properties of three-point bending were tested by mechanical testing machine,and the elastic modulus and maximum load were obtained.The bone mineral density and trabecular thickness of lumbar vertebrae,femurs and skulls were measured by dual energy X-ray absorptiometry,and the number of osteoclasts was detected by tartrate-resistant acid phosphatase staining(TRAP).The blood of abdominal aorta of mice was collected and serum ALP and DPD were detected by ELISA.The tissues of femur and tibia were taken,and the cells in bone marrow cavity washing fluid were collected,and RT-PCR was used to detect EphrinB2 and EphB4 mRNAs and Western blotting was used to detect EphrinB2 and EphB4 proteins.Results Com-pared with the sham operation group,the bone elastic modulus and maximum load decreased in the model group;com-pared with the model group,the bone elastic modulus and maximum load increased in the intervention group(all P<0.05).Compared with the sham operation group,the bone mineral density and trabecular thickness in the model group decreased;compared with the model group,the bone mineral density and trabecular thickness increased in the interven-tion group(all P<0.05).The number of osteoclasts was larger in the model group than in the sham operation group and the intervention group(both P<0.05).Compared with the sham operation group,the levels of serum ALP and DPD in the model group decreased;compared with the model group,the levels of serum ALP and DPD increased in the intervention group(all P<0.05).Compared with the sham operation group,the mRNA and protein expression levels of EphrinB2 and EphB4 in the model group decreased;compared with the model group,the mRNA and protein expression levels of Eph-rinB2 and EphB4 increased in the intervention group(all P<0.05).Conclusion Overexpression of EphrinB2/EphB4 signaling pathway proteins demonstrates the ability to enhance bone mechanical properties,reduce the number of osteo-clasts,and improve bone metabolic indicators of ovariectomized mice,suggesting that this strategy may prevent and treat postmenopausal osteoporosis.
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