A hypomagnetic field aggravates bone loss induced by hindlimb unloading in rat femurs

• Published in: PloS one Vol. 9; no. 8; p. e105604
• Main Authors: Jia, Bin, Xie, Li, Zheng, Qi, Yang, Peng-fei, Zhang, Wei-ju, Ding, Chong, Qian, Ai-rong, Shang, Peng
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.08.2014; Public Library of Science (PLoS)
• Subjects: Animals; Astronauts; Biocompatibility; Biology and Life Sciences; Biomechanics; Biomedical materials; Biophysics; Biotechnology; Bone density; Bone loss; Bone mineral density; Bone resorption; Bone Resorption - etiology; Bone Resorption - pathology; Computer simulation; Earth Sciences; Endocrinology; Femur; Femur - pathology; Geomagnetic field; Geomagnetism; Gravity; Hindlimb Suspension - adverse effects; Laboratories; Life sciences; Magnetic fields; Magnetic Fields - adverse effects; Magnetic shielding; Male; Medicine and Health Sciences; Metabolism; Microgravity; Moon; Osteoblasts; Osteoclasts; Osteoclasts - pathology; Osteoporosis; Oxidative stress; Oxygen; Physical Sciences; Rats; Rats, Sprague-Dawley; Reactive oxygen species; Research and Analysis Methods; Rodents; Skeletal system; Space exploration; Space missions; Trace elements; Transplants & implants; Unloading; Weightlessness; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0105604

A hypomagnetic field is an extremely weak magnetic field--it is considerably weaker than the geomagnetic field. In deep-space exploration missions, such as those involving extended stays on the moon and interplanetary travel, astronauts will experience abnormal space environments involving hypomagnetic fields and microgravity. It is known that microgravity in space causes bone loss, which results in decreased bone mineral density. However, it is unclear whether hypomagnetic fields affect the skeletal system. In the present study, we aimed to investigate the complex effects of a hypomagnetic field and microgravity on bone loss. To study the effects of hypomagnetic fields on the femoral characteristics of rats in simulated weightlessness, we established a rat model of hindlimb unloading that was exposed to a hypomagnetic field. We used a geomagnetic field-shielding chamber to generate a hypomagnetic field of <300 nT. The results show that hypomagnetic fields can exacerbate bone mineral density loss and alter femoral biomechanical characteristics in hindlimb-unloaded rats. The underlying mechanism might involve changes in biological rhythms and the concentrations of trace elements due to the hypomagnetic field, which would result in the generation of oxidative stress responses in the rat. Excessive levels of reactive oxygen species would stimulate osteoblasts to secrete receptor activator of nuclear factor-κB ligand and promote the maturation and activation of osteoclasts and thus eventually cause bone resorption.