Correlation of the Expression of IGF-1, TGF-β1 and BMP12 with Tendon Degeneration Caused by Overused Tendon of the Long Head of Biceps Brachii

Abstract

Objective: To assess the association of the expression of insulin-like growth factor-1 (IGF-1), transforming growth factor beta-1 (TGF-β1) and bone morphogenetic protein-12 (BMP-12) with tendon degeneration in rats caused by overuse of biceps brachii long head tendon. Methods: Sixteen Sprague-Dawley (SD) rats were randomly divided into normal group (n = 8) and overuse group (n = 8). Rats were fed routinely in normal group and were treated by small animal treadmills for continuous 6 weeks of exercise at 1 h/day in overuse group followed by analysis of histological morphology of the tendon of the long head of biceps brachii by Hematoxylin-eosin (HE) staining, the expression levels of IGF-1, TGF-β1 and BMP-12 by Western blotting. Correlation analysis was used to analyze the correlation of the protein expression with the pathological score. Results: HE staining showed normal morphology of biceps brachii long head tendon in normal group (with dense structure, uniform arrangement and no fiber damage) and abnormal morphology in overuse group (with disordered structure, uneven arrangement and some of breakage fibers). The pathological score in overuse group was significantly higher than that in normal group (p < 0.05). Compared with those in normal group, the protein levels of IGF-1, TGF-β1 and BMP-12 were significantly elevated in overuse group (p < 0.05). Conclusion: The expression of IGF-1, TGF-β1 and BMP-12 in overused tendon of the long head of the biceps brachii are elevated, and positively correlated with tendon degeneration.