Effect Of Exercise And Low Frequency Pulsing Electromagnetic Fields On Nitrogen Oxide And Bone Remodeling In Ovariectomized Rats

Effect of Exercise and Low Frequency Pulsing Electromagnetic Fieldson Nitrogen Oxide and Bone Remodeling in Ovariectomized RatsOsteoporosis is one of the diseases with high morbility,death rateand cost of health care In the world at present.It Has become globalproblem of public hygiene.Morbility of osteoporosis has been high moreand more. The means of medicine treatment is limted to be used for thehigh cost and side-effect,therefore it is significant using non-medicinemeans to prevent and allieviate the loss of bone mineral and finding asecure,convenient and economic treating means.Forty 3-month-old female SD rats were divided into 5 groups randomly:imitate surgery control groups(SHAM),ovariectomized control groups(OVX1),ovariectomized plus exercise training groups(OVX2),ovariecto-mized treated groups with PEMFs (OVX3), and ovariectomized treated groupswith PEMFs and exercise training(OVX4).Both ovaries of OVX rats wereextirpated, the SHAM group underwent an imitate operation.The exercisemodel was built with moderate-load treadmill running (20m/min,1h/d,5d/w).the PEMFs treated group received a PEMFs therapy focused on lowerlimbs and lumbar(50Hz,20～40GS,1h/d,5d/w).OVX4 group treated with bothtreadmill running and PEMFs therapy. The methods of Bone Morphometry andBone Biomechanics were used to evaluate the prevention and therapy effectof treadmill running and PEMFs on OVX rats based on the study of thechanges of the NO and NOS in blood and bone.Meanwhile it's mechanism hasbeen discussed.The results showed:1.The content of the estrogen in serum and theweight of the uterus in all the OVX groups after 10 weeks were lower thanthose in the sham group.The content of the NO and the activity of the NOSin serum and bone reduced significantly in the ovariectomized controlgroup. So did the parameters of the bone morphometry such as the TBV, MTTand MCT. The value of the FS, RS and MAR increased in the OVX groups.2.Exercise group and PEMFs therapy could accelerate the value of the TBV,MTT and MCT significantly on ovariectomized rats. The combination of themcould do more than one did.The RS in exercise and PEMFs groups was lowerthan that in ovariectomized control group distinctly, the value of theFS was similar as OVX group.The combination of exercise and PEMFs therapycould reduce RS more.Both exercise and PEMFs therapy could reduce MAR andthe numbers of the OC,increasing the percentage of the fluorochromecircumference labeled by tetracycline. The number of the OC could reducedmore by the combination of them.3.Exercise and PEMFs therapy could improvethe structure and function of the material mechanics of the femur andlumbar vertebra in all the OVX rats.There had no significant differenceon improving the biomechanics of the femur and lumbar vertebra betweenthe two methods.the combination of two ways made the index of energyabsorption,maximum distortion,specific energy in three point bendexperiment and the index of maximum compression load,energy absorption,maximum compressive stress, elastic modulus in lumbar bone compressionexperiment higher than experiment separately.4.Exercise and PEMFstherapy could improve the content of the NO and NOS in serum and bone.The difference was that exercise could improve cNOS more than iNOS.Otherwise PEMFs therapy could improve iNOS more than cNOS. The combinationof the exercise and PEMFs therapy could improve the content of the NO andNOS in serum and bone more distinctively.Summarizing the main finding of this study, we conclude that:1.The three months Sprague-Dawley rats represented osteoporosis with highbone turnover rate and the remodeling of the bone became a negative balanceafter ovariectomized for 10 weeks. These changes confirmed that thepostmenopausal osteoporosis model of rats had been establishedsuccessfully.2.Exercise and PEMFs could control the pathology of the high bone turnoverrate of the ovariectomized rats effectively, prevent the more loss of thebone mass, and improve the biomechanics capability of os integumentaleand cancellated bone. Therefore, exercise and PEMFs could prevent andtreat the postmenopausal osteoporosis at a certain extent.3.Exercise and PEMFs therapy could accelerate the bone form and inhibitthe bone absorbtion of the ovariectomized rats, but the effect of theinhibition of bone absorbtion was the primary process.Thereby,the highrate of the bone turnover was controlled,and the loss of bone mass wasreduced.4.The increase of NO,NOS induced by exercise and PEMFs could inhibit theOC bone absorbtion,reduce the high turnover rate of bone remodeling.Itmay be one of the same mechanisms of the treatment on the osteoporosisby exercise and PEMFs. But exercise could improve the activity of the cNOS,and PEMFs improve the activity of iNOS in the bone.5.On controlling the high rate of the bone turnover of the ovariectomizedrats and the improvement of the biomechanics capability of bone,the effectof the therapeutics combined exercise with PEMFs was better than thatapplied exercise or PEMFs respectively.So the therapy of exercisecombined with PEMFs on prevention and treatment the postmenopausalosteoporosis will produce a better curative effect.As a none-drug methodof preventing and curing the osteoporosis it is worthy to be generalized.