ABSTRACT
Objective To investigate the effect of treadmill running with different intensities on type Ⅱ collagen (Col2) of knee joint articular cartilages in rats.Methods A total of 48 adult Sprague-Dawley rats were randomly divided into a control (C) group,a low-intensity exercise (L) group,a moderate-intensity exercise (M)group and a high-intensity exercise (H) group,each of 12.Rats in three exercises groups were regularly trained on treadmill at low,moderate,and high intensities respectively.Eight weeks later,all the animals were sacrificed.The right tibial plateau samples were collected to observe collagen fibers under polarizing light microscopy,and the collagen Ⅱ content were examined using immunohistochemistry.The mRNA expression of biglycan (BGN),fibromodulin (FMOD) and Col2 was tested using the quantitative real-time reverse transcription-polymerase chain reaction.Results Compared with group C,collagen fibers in group L and M exhibited almost the same organization,whereas,alteration in organization and shape of collagen fibers was found in group H.Significantly lower content of type Ⅱ collagen was found in group H than that in group C.In comparison with group C,group L had significantly higher gene expression of Col2,whereas group H had significantly higher BGN mRNA expression.Conclusion Low-or moderate-intensity treadmill running appears to have beneficial effect on articular cartilages to maintain its integrity.Highintensity exercises induce lower content and disorder of type Ⅱ collagen in articular cartilages,but the self-healing of cartilage may still exist.