The Study Of Growth Factor’s Protein Expression Characteristics In Tendon During Overuse Process

It is still unclear that the pathological mechanism of tendon degeneration induced by overuse-induced. Some researchers suggest that long-term Exposure to growth factors could make tenocytes’function abnormal, and cumulative fatigue damage causes tendon degeneration. in order to study the role of growth factors in tendon degeneration overuse-induced, we established the rats tendon overused model by10°downhill running (speed22m/s), We conducted the exercise for1.5hours per day, six times per week. We harvested Achilles tendons after2,4,6, and8weeks of exercise, than detected of pathological changes and growth factor protein expression in various stages of overuse by immunohistochemistry, immunof luorescence method, the main results were as follows:1. Pathology score gradually increased with overuse time, reached the highest level at4-6weeks (P<0.01). The most significant changes were in arrangement of collagen fibers, nuclear morphology, tenocytes distribution, collagen dyeability (P<0.05).2. Tenocytes apoptosis increased significantly after2weeks (P<0.05), and reached high level at4-8weeks (P<0.01). Proliferation of tenocytes was not observed during the downhill running.3. In whole tendon, bFGF protein expression was significantly increased during the downhill running, but TGFβ1, bFGF and BMP12had no significantly change. BFGF was significantly increased at2weeks (P<0.01), decreased at4weeks, and raised again at6-8weeks (P<0.05).4. In rat biceps brachii tendon intertubercular sulcus parts, IGF1expression had no significantly change, but expression of TGF β1, bFGF, and BMP12were significantly increased. The expression of TGF β1increased gradually, reached a peak at6weeks (P<0.05), decreased rapidly at8weeks. The expression of bFGF raised slowly, reached the peak at4weeks value (P<0.01), and then decreased at8weeks. The expression of BMP12protein increased gradually, reached a peak at6weeks (P<0.05), and declined slightly at8weeks.Conclusion:1. Downhill running could cause degenerative changes in rat biceps brachii tendon intertubercular sulcus parts.2. Excessive Apoptosis and insufficient proliferation of tenocytes is an important pathological phenomenon of tendon degeneration by overused-induced, can lead to the decrease in the number of tenocytes, weakening the tendon repair ability.3. During overuse process, long-term abnormal expression of growth factors was an important pathological chang of tendon degeneration.4. The growth factors expression were different between biceps brachii tendon intertubercular sulcus parts and whole tendon. Not all growth factors’ protein expression would be changed.