The Effect of Pulsed Electromagnetic Field on Apoptosis Proteins in Articular Cartilage and Subchondral Bone of Elderly Rats
Objective:To explore the effects of pulsed electromagnetic fields on apoptosis proteins in articular cartilage and subchondral bone of elderly rats.Methods:Sixteen 24-month-old SD naturally aging male rats were randomly divided into an elderly group and a pulsed electromagnetic group using random sampling method.Eight 6-month-old SD young male rats were selected as the youth group.The pulsed electromagnetic group received pulsed electromagnetic field intervention at a frequency of 8 Hz and an intensity of 3.82 Mt,with a duration of 40 minutes per day and 5 days per week for 8 weeks.The youth and elderly groups were fixed under pulsed electromagnetic fields,and the instruments were not powered on.After 8 weeks,samples were taken and ELISA was used to detect the content of C-telopeptide of typeⅡcollagen(CTX-Ⅱ)in serum;Micro CT(Micro-CT)was used to detect the microstructure of the left tibial subchondral bone and analyze quantitative indicators of bone tissue morphology;the morphological structure of the cartilage tissue on the left tibial plateau of rats was observed using safranin O-solid green staining,and the degree of degenerative changes in the knee joint cartilage tissue of rats was evaluated using the improved Mankin's score.RT-Qpcr and Western blot were used to detect the Mrna and protein expression levels of Caspase-3,Caspase-8,ADAMTS-4 and ADAMTS-5.Results:①Compared with the young group,the CTX-Ⅱ level of cartilage collagen decomposition product in the elderly group rats increased(P<0.05);bone density,bone volume fraction,and number of trabeculae all decreased(P<0.05),while bone trabecular thickness and spacing increased(P<0.05);safranin O-solid green staining showed that the surface of rat cartilage was rough with cracks,the boundary between cartilage and subchondral bone was unclear,and there was a tidal line,low cell count,irregular cell morphology and structure,loss of proteoglycans,and pale red staining;improved Mankin's score increased(P<0.05);the Mrna and protein expression of Caspase-3,Caspase-8,ADAMTS-4,and ADAMTS-5 increased(P<0.05).② Compared with the elderly group,the CTX-Ⅱ level of cartilage collagen decomposition products in the pulsed electromagnetic group rats decreased(P<0.05);the bone density and bone volume fraction of the subchondral bone of the left tibia increased,the number of trabeculae increased(P<0.05),the distance between trabeculae decreased(P<0.05),and the thickness of trabeculae showed a decreasing trend(P>0.05);safranin O-solid green staining showed that the surface of rat cartilage was relatively flat,with clear boundaries between cartilage and subchondral bone,the cell morphology was more regular and numerous,and protein polysaccharides were abundant and evenly stained;the improved Mankin's score was relatively small(P<0.05);the Mrna and protein expression of Caspase-3,Caspase-8,ADAMTS-4,and ADAMTS-5 decreased(P<0.05).Conclusion:Pulsed electromagnetic fields may delay articular cartilage degeneration and extracellular matrix degradation in elderly rats,inhibit local osteoporosis,and exert anti osteoarthritis effects by reducing the expression of apoptosis related proteins Caspase-3 and Caspase-8,as well as the expression of metalloproteinases ADAMTS-4 and ADAMTS-5.
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