RESUMO
OBJECTIVE: To advance the understanding of how alterations in exercise speed and grade (flat vs 17° incline or decline) affect the quality of tendon healing, and to determine if a biomarker relationship exists between serum levels of a ColX breakdown product (CXM) and animals exposed to treadmill running protocols. ANIMALS: 35 male mice (C57BL/6J), 8 weeks of age. PROCEDURES: Mice were preconditioned on a treadmill for 14 days. Tendinopathy was then induced by 2 intra-tendinous TGFß1 injections followed by randomization into 7 exercise groups. Exercise capacity and objective gait analysis were measured weekly. Mice were euthanized and histopathologic analysis and evaluation of serum CXM levels were performed. Statistics were conducted using a 2-way ANOVA (exercise capacity), Mixed Effects Model (gait analysis, effect of preconditioning), and 1-way ANOVA (gait analysis, the effect of injury, and rehabilitation normalized to baseline; CXM serum analysis), all with Tukey post hoc tests and significance set to P < .05. RESULTS: Exercise at a fast-flat speed demonstrated inferior tendinopathic healing at the cellular level and impaired stance braking abilities, which were compensated for by increased propulsion. Mice exposed to exercise (at any speed or grade) demonstrated higher systemic levels of CXM than those that were cage rested. However, no ColX immunostaining was observed in the Achilles tendon or calcaneal insertion. CLINICAL RELEVANCE: Exercise at a fast speed and in absence of eccentric loading components (incline or decline) demonstrated inferior tendinopathic healing at the cellular level and impaired braking abilities that were compensated for by increased propulsion.
Assuntos
Tendão do Calcâneo , Doenças Musculoesqueléticas , Tendinopatia , Masculino , Camundongos , Animais , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Tendinopatia/terapia , Tendinopatia/veterinária , Doenças Musculoesqueléticas/patologia , Doenças Musculoesqueléticas/veterinária , Tendão do Calcâneo/metabolismo , Tendão do Calcâneo/patologiaRESUMO
Axolotl salamanders (Ambystoma mexicanum) remain aquatic in their natural state, during which biomechanical forces on their diarthrodial limb joints are likely reduced relative to salamanders living on land. However, even as sexually mature adults, these amphibians can be induced to metamorphose into a weight-bearing terrestrial stage by environmental stress or the exogenous administration of thyroxine hormone. In some respects, this aquatic to terrestrial transition of axolotl salamanders through metamorphosis may model developmental and changing biomechanical skeletal forces in mammals during the prenatal to postnatal transition at birth and in the early postnatal period. To assess differences in the appendicular skeleton as a function of metamorphosis, anatomical and gene expression parameters were compared in skeletal tissues between aquatic and terrestrial axolotls that were the same age and genetically full siblings. The length of long bones and area of cuboidal bones in the appendicular skeleton, as well as the cellularity of cartilaginous and interzone tissues of femorotibial joints were generally higher in aquatic axolotls compared with their metamorphosed terrestrial siblings. A comparison of steady-state mRNA transcripts encoding aggrecan core protein (ACAN), type II collagen (COL2A1), and growth and differentiation factor 5 (GDF5) in femorotibial cartilaginous and interzone tissues did not reveal any significant differences between aquatic and terrestrial axolotls.