title: A hypomagnetic field aggravates bone loss induced by hindlimb unloading in rat femurs.
abstract: 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.
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Jia
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Li
authors.initials: L
authors.lastname: Xie
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Peng-fei
authors.initials: PF
authors.lastname: Yang
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Wei-ju
authors.initials: WJ
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Ding
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Ai-rong
authors.initials: AR
authors.lastname: Qian
authors.affiliation: Key Laboratory for Space Bioscience and Biotechnology, Institute of Special Environmental Biophysics, School of Life Sciences, Northwestern Polytechnical University, Xi'an, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Shang
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000209:etiology* / Q000473:pathology; D005269:Femur / Q000473:pathology*; D019417:Hindlimb Suspension / Q000009:adverse effects*; D060526:Magnetic Fields / Q000009:adverse effects*; D008297:Male; D010010:Osteoclasts / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014893:Weightlessness