Pulsed electromagnetic fields prevented the decrease of bone formation in hindlimb‐suspended rats by activating sAC/cAMP/PKA/CREB signaling pathway

作者：Wen‐Yuan Li, Xueyan Li, Yonghui Tian, Xin‐Ru Chen, Jian Zhou, Baoying Zhu, Hui‐Rong Xi, Yuhai Gao, Cory J. Xian, Keming Chen · 发表于：Bioelectromagnetics · 年份：2018 · DOI：10.1002/bem.22150 · 被引用次数：17 · 研究领域：Spaceflight effects on biology、Electromagnetic Fields and Biological Effects、Genetics, Aging, and Longevity in Model Organisms

Microgravity is one of the main threats to the health of astronauts. Pulsed electromagnetic fields (PEMFs) have been considered as one of the potential countermeasures for bone loss induced by space flight. However, the optimal therapeutic parameters of PEMFs have not been obtained and the action mechanism is still largely unknown. In this study, a set of optimal therapeutic parameters for PEMFs (50 Hz, 0.6 mT 50% duty cycle and 90 min/day) selected based on high-throughput screening with cultured osteoblasts was used to prevent bone loss in rats induced by hindlimb suspension, a commonly accepted animal model to simulate the space environment. It was found that hindlimb suspension for 4 weeks led to significant decreases in femoral and vertebral bone mineral density (BMD) and their maximal loads, severe deterioration in bone micro-structure, and decreases in levels of bone formation markers and increases in bone resorption markers. PEMF treatment prevented about 50% of the decreased BMD and maximal loads, preserved the microstructure of cancellous bone and thickness of cortical bone, and inhibited decreases in bone formation markers. Histological analyses revealed that PEMFs significantly alleviated the reduction in osteoblast number and inhibited the increase in adipocyte number in the bone marrow. PEMFs also blocked decreases in serum levels of parathyroid hormone and its downstream signal molecule cAMP, and maintained the phosphorylation levels of protein kinase A (PKA) a...