title: Biochemical and morphological alterations in the Achilles tendon of mdx mice.
abstract: Dystrophin-deficient muscles have repeated cycles of necrosis and regeneration, being susceptible to injury induced by muscle contractions. Some studies have demonstrated that tendons are also affected in mdx mice, based especially on the changes in biomechanical properties arising from the respective linked muscles. However, most studies have focused only on alterations in the myotendinous junction. Thus, the purpose of this work was to study biochemical and morphological alterations in the Achilles tendons of 60-day-old mdx mice. Hydroxyproline quantification, showed higher collagen concentration in the mdx mice as compared with the control. No difference between the tendons of both groups was found in the noncollagenous proteins dosage, and in the amount of collagen type III detected in the western blotting analysis. The zymography for gelatinases detection showed higher amounts of metaloproteinase-2 (active isoform) and of metalloproteinase-9 (latent isoform) in the mdx mice. Measurements of birefringence, using polarization microscopy, showed higher molecular organization of the collagen fibers in the tendons of mdx mice in comparison to the control group, with presence of larger areas of crimp. Ponceau SS-stained tendon sections showed stronger staining of the extracellular matrix in the mdx groups. Toluidine blue-stained sections showed more intense basophilia in tendons of the control group. In morphometry, a higher number of inflammatory cells was detected in the epitendon of mdx group. In conclusion, the Achilles tendon of 60-day-old mdx mice presents higher collagen concentration and organization of the collagen fibers, enhanced metalloproteinase-2 activity, as well as prominent presence of inflammatory cells and lesser proteoglycans.
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, State University of Campinas-UNICAMP, Campinas, São Paulo, Brazil.
authors.forename: Andrea Aparecida
authors.initials: AA
authors.lastname: De Aro
authors.forename: Flávia Da Ré
authors.initials: Fda R
authors.lastname: Guerra
authors.forename: Marcelo Augusto Marretto
authors.initials: MA
authors.lastname: Esquisatto
authors.forename: Wilson Romero
authors.initials: WR
authors.lastname: Nakagaki
authors.forename: Laurecir
authors.initials: L
authors.lastname: Gomes
authors.forename: Edson Rosa
authors.initials: ER
authors.lastname: Pimentel
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D005109:Extracellular Matrix / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D051379:Mice; D018101:Mice, Inbred mdx; D009136:Muscular Dystrophies / Q000378:metabolism / Q000473:pathology
chemical_list: D020778:Matrix Metalloproteinase 2
keywords: collagen; dystrophy; extracellular matrix; metalloproteinase; organization