Effect of 900MHz Radiofrequency Field on Bone Microarchitecture and Metabolism in Ovariectomized Mice

• 1、Soochow University,suzhou,215123

Abstract：[Objective] To investigate the effect of 900MHz radiofrequency radiation on microarchitecture and metabolism of femur in ovariectomized mice. [Methods]Sixty 3-month-old female C57BL/6 mice were randomly divided into six groups(n=10): Sham (sham exposure), OVX (ovariectomy), OVX+LRF、OVX+MRF、OVX+HRF (50μW/cm2、150μW/cm2 and 450μW/cm2 radiofrequency radiation post OVX)、OVX+E2 (0.04mg/kg estrogen injection post OVX) groups. After four weeks of continuous intervention, the mice were sacrificed. The serum samples of all mice were collected and the levels of E2, BALP, BGP, OPG, CTX-Ⅰ and TRACP-5b were detected with Elisa assays. The microstructure and morphology of femur were observed with microcomputed tomography (micro-CT), the parameters of bone, including BMD, BV, TV, BV/TV, Tb. N, Tb.Th, and Tb.Sp, were calculated from the reconstructed images. The mRNA expression of Runx2 and NFATc1, which are considered as osteoclast and osteoblast differentiation transcription factors respectively, were determined by real-time PCR. The levels of OPG and RANKL proteins were detected using Immunohistochemical staining. [Results]After ovariectomy, a significant decrease in the level of serum E2 was observed in mice, while the level of serum E2 was significantly increased following E2 treatment(P<0.05). Compared with Sham group, the levels of serum BGP, OPG, CTX-Ⅰ and TRACP-5b were significantly increased in OVX group(P<0.05); Following RF and E2 treatment, the levels of serum BGP in OVX+MRF and OVX+E2 groups were significantly increased while CTX-Ⅰ and TRACP-5b were significantly decreased compared that with OVX group, (P<0.05). Micro- CT results showed that compared with the sham exposure group, the BMD and BV, BV/TV, Tb.Th, Tb.N in OVX group decreased significantly while Tb.Sp increased significantly(P<0.05), the 3D images of femur showed severe loss of bone trabeculae and loose structure. After radiofrequency radiation and estrogen intervention, BMD and the above indicators improved significantly (P<0.05), and the deterioration of trabecular bone structure was significantly improved. Among the three doses of RF groups, the effect of 150μW/cm2 RF was the most significant. Compared with Sham group, the expression of Runx2 and NFATc1 mRNA increased significantly in OVX group(P<0.05); After radiofrequency radiation and estrogen intervention, Runx2 mRNA expression increased significantly, while NFATc1 mRNA decreased significantly (P<0.05); The western blot results showed that the levels of OPG and RANKL protein in OVX group were significantly increased, and the OPG/RANKL ratio was significantly lower than that in control group (P<0.05); Compared with OVX group, OPG/RANKL ratio was significantly increased in OVX+MRF group and OVX+E2 group. [Conclusion]150μw/cm2 900MHz radiofrequency irradiation could antagonize the changes of serum bone metabolism biomarkers, the decrease of bone mineral density, the deterioration of bone microstructure and the increasing bone resorption in mice induced by ovariectomy.

Keywords： radio frequency electromagnetic field Ovariectomy Bone metabolism Osteoporosis Micro-CT