Exercise increases tendon collagen synthesis and cross-link formation. Exercise also increases the expression of TGF-β1. TGF-β1 may contribute to the upregulation of tendon collagen synthesis during exercise, but this relationship has not been established in vivo. The purpose of this study was to evaluate the effects of TGF-β1 receptor inhibition on tendon collagen. Male Wistar rats were divided into sedentary (SED, n = 9) or exercised (RUN, n=15) groups. Exercised animals completed four days of treadmill exercise (60 minutes/days). The peritendinous space of one Achilles tendon was injected with LY-364947 (ALK5 inhibitor; INHIB) while the opposite leg was injected with a vehicle (SHAM). Injections were given daily after each exercise bout. ERK and Smad 2/3 phosphorylation was evaluated by Western blotting. Collagen I and III gene expression were evaluated via qRT-PCR. Tendon hydroxyproline and hydroxylyslpyridinoline (HP) cross-linking were assayed via HPLC. A longitudinal section of tendon was stained with H&E for evaluation of cell numbers and fibril organization.Introduction
Materials and Methods
