The Anti-bone Loss Effects Of Pulsed Electromagnetic Fields Induced By Weightness And Its Signal Transduction Mechanism

With the development of the manned aviation industry,astronauts have become more and more concerned about the physical condition caused by weightlessness in space.One of the most serious problems is the loss of bone caused by weightlessness,such as the atrophy of muscle and skeletal system of bearing bones.Weightlessness will lead to a significant decrease in bone mass,eventually leading to the occurrence of osteoporosis,which has become a major problem for aerospace companies around the world.So it is imminent to study methods for treatment and prevention.The study found that electromagnetic field treatment of osteoporosis is a safe and reliable method.It has recently been considered as one of the potential countermeasures for prevention of bone loss due to weightlessness.To this end,our group first established a tail-suspended rat model by simulating spatial weightlessness.The rats were treated with 50 Hz 0.6 m T PEMFs daily for 90 minutes.After 4 weeks,the rats were killed.The femurs and vertebrae were detached to measure the bone mineral density.The biomechanics and bone were analyzed.Tissue morphology,serum was separated for biochemical indicators,and rat gene protein levels were studied.The main research purpose of this experiment is to study the effect of pulsed electromagnetic field on prevention of bone mass loss in tail-suspended rats and its mechanism of action,providing theoretical reference and scientific basis for prevention of bone loss caused by weightlessness.Experimental method: This experiment first constructed a model of simulated micro-gravity rat tail suspension.Three groups of rats were divided into control group,HLS group and PEMFs treatment group,and then treated with 50 Hz 0.6 m T PEMFs.The intervention was 90 min per day,4 Rats were sacrificed after the week.The effect of PEMFs on the bone mineral density and biomechanical strength of rats was measured for the first time;secondly,the concentration of OC and PINP(bone formation markers),TRACP 5b and CTX-1 absorption markers in serum were further measured by ELISA kits.Microscopic CT and VG staining were used to observe the bone histomorphometry and quantitative analysis.Changes of osteoblasts and adipocytes in the bone marrow were observed again by HE staining.Then the bone-related gene protein(RUNX-2 BMP-2 and OSX)was observed by RT-PCR and Western blot.Evaluate the effect of electromagnetic field on the bone quality of tail-suspended rats.Finally,ELISA kit was used to detect the levels of PTH and c AMP,as well as the phosphorylation level of PKA and CREB to study the specific signal pathway of electromagnetic field to improve the bone quality of tail-suspended rats and explore its mechanism of action.Experimental results: In this experiment,PEMFs(50 Hz,0.6 m T,90 min/day)selected by the laboratory based on large-scale in vitro cultured osteoblasts and animal experimental methods were the best treatment parameters to further explore the electromagnetic field pairs.The therapeutic effect of the tail suspension model.In this study,tail-suspension model rats were used to simulate microgravity on the ground.Four weeks after the hindlimb suspension of rats,the effects of the tail suspension model were evaluated by comparing the effects on bone density and biomechanics of femur and vertebrae in rats.Compared to the HLS group,pulsed electromagnetic field treatment prevented about a 50% reduction in bone mineral density and maximum load value.The experimental results showed that the content of bone formation markers(OC and PINP)increased significantly under pulsed electromagnetic field treatment,but the decrease in bone resorption markers(TRACP 5b and CTX-1)was not significant,indicating that PEMFs were more pronounced Promotes bone resorption.Through micro-CT and VG staining results,it was found that PEMFS treatment can significantly improve the bone microarchitecture of cancellous and cortical bone in rats,and prevent bone structure from being affected by tail suspension and worsening.The femoral bone marrow cavity was observed by HE staining,indicating that the pulsed electromagnetic field can significantly increase the number of osteoblasts and inhibit the increase of the number of adipocytes in the bone marrow.PEMFs can also prevent the bone level markers PTH and its downstream signaling molecules.Decrease in c AMP and maintain phosphorylation levels of PKA and CREB.The level of expression of soluble adenylyl cyclase(s AC)is also maintained.Conclusion: Treatment of PEMFs at 50 Hz and 0.6 m T can effectively increase the bone mineral density and biomechanics of tail-suspended rats,promote the concentration of bone formation markers in rat blood,and increase the content of osteoblasts to prevent the deterioration of bone microstructure.A good type of electromagnetic field treatment.PEMFs are used to promote bone formation through the SAC/c AMP/PKA/CREB pathway to prevent bone mass loss in tail-suspended rats.