Efficacy of static magnetic field for locomotor activity of experimental osteopenia.

In order to examine the effectiveness of applying a static magnetic field (SMF) for increasing bone mineral density (BMD), we assessed the degree of osteopenia by dual-energy X-ray absorptiometry (DEXA), the metabolism measuring system, and histological examination of bone tissue in an ovariectomized (OVX) rat model. Thirty-six female Wistar rats (8 weeks old, 160-180 g) were divided into three groups. The rats in the OVX-M group were exposed to SMF for 12 weeks after ovariectomy. The ovariectomized rats in the OVX-D group were not exposed to SMF as a control. The rats in the normal group received neither ovariectomy nor exposure to SMF. Twelve-week exposure to SMF in the OVX-M group inhibited the reduction in BMD that was observed in the OVX-D group. Moreover, in the OVX rats, before exposure to SMF, there was no clear difference in the level of locomotor activity between the active and resting phases, and the pattern of locomotor activity was irregular. After exposure of OVX rats to SMF, the pattern of locomotor activity became diphasic with clear active and resting phases, as was observed in the normal group. In the OVX-M group, the continuity of the trabecular bone was maintained more favorably and bone mass was higher than the respective parameters in the OVX-D group. These results demonstrate that exposure to SMF increased the level of locomotor activity in OVX rats, thereby increasing BMD.