Rat Articular Cartilage Of Knee Joint In Response To Strenuous Running Exercise Of Various Gradient

Objective To study expression of MMP-3and MMP-13in rat articular cartilage of knee joint in response to strenuous running exercise of various gradient.Method24male Wistar rats were randomly divided into the running group and no running group.The group of no runing namely freedom group(n=6) were fed in the cage.18male wistar rats which were divided to3parts started running with the speed of1000m/h and the distance of1000m on a treadmill at3kinds of gradient(-20°、0°、+20°) every day.Thereafter,the rats were trained for45days continuously.The gross pathology and the immunohistochemistry of MMP-3,MMP-13were measured.Result HE,toluidine blue stain show that the joint surface become rough and denudations appeared,tide lines were not integrated in the+20°running group.Immunohistochemisty stain show the expression of MMP-3,MMP-13increased sharply in the+20°running group. The safranin O staining of non-running group showed that the chondrocytes are arranged regularly, and the tidemark of cartilage was clear. And the running group showed that each layer structure boundary disappeared and the tidemark of cartilage was disordered.The OARSI score of the medial tibia in each running group was obviously increased the femur inside.Compare with the+20°running group,the OARSI score of the medial tibia of-20°running group or0°running group was significantly decreased(P<0.05). Compare with the+20°running group,the OARSI score of the the femur inside of-20°running group was significantly decreased(P<0.05). The scores of Mankin’s grades in the non-running group,+20°group,0°group and-20°group were0.67±0.52,9.00±1.34,7.50±0.76and4.33±0.71. There were significant differences among all the groups(P<0.05).Conclusion Strenuous running induced conspicuous decrease of collagen Ⅱ and aggrecan in the articular cartilage,especially in the+20°running group. It may indicate that strenuous running with an up-gradient was much easier to damage articular cartilage of knee joint.