Muscular Dystrophy on Oxidative State in Masticatory Muscles of MDX Mice

  • Prof Tomas Gedrange, Department of Orthodontics, Preventive and Pediatric Dentistry, Ernst-Moritz-Arndt University Greifswald, Germany, Germany
  • Dr Alexander Spassov, Department of Orthodontics, Preventive and Pediatric Dentistry, Ernst-Moritz-Arndt University Greifswald, Germany, Germany
  • Dr Tomas Gredes, Department of Orthodontics, Preventive and Pediatric Dentistry, Ernst-Moritz-Arndt University Greifswald, Germany, Germany
  • Prof András Végh, Department of Orofacial Orthopedics and Orthodontics, Heim Pál Children’s Hospital, Budapest, Hungary, Hungary
  • Dr Gabriella Borsos, Department of Orofacial Orthopedics and Orthodontics, Heim Pál Children’s Hospital, Budapest, Hungary, Hungary
  • Dr E Segatto, Department of Orofacial Orthopedics and Orthodontics, Heim Pál Children’s Hospital, Budapest, Hungary, Hungary
  • Dr Christiane Kunert-Keil, Department of Orthodontics, Preventive and Pediatric Dentistry, Ernst-Moritz-Arndt University Greifswald, Germany, Germany

Aim: Duchenne Muscular Dystrophy (DMD) and its murine model, mdx, are characterized by muscle damage and increased oxidative stress. Furthermore, DMD patients have distorted dentofacial morphology which could be a result of changed masticatory mechanics due to muscular dysfunction. To determine potential changes in masticatory mechanics we searched for morphological abnormalities including nuclei localization, fibre diameters, collagen and myosin heavy chain (MyHC)-isoforms expression in control and mdx mice. In addition we analyzed the GSH (glutathione) content.
Material and Methods: Muscle sections were stained with hemalaun/eosin and Sirius Red. The mRNA and protein levels of the MHC-isoforms were studied using quantitative RT-PCR, Western blot analyses and histochemistry in masseter (MAS), temporal (TEM), tongue (TON) and soleus (SOL) of both mouse strains.
Results: Mdx masticatory muscles contained 11-75% fibres with centralized nuclei, numerous inflammatory foci and an accumulation of collagen except TON. Furthermore, a significant increased mean fibre diameter was observed in all tested mdx muscles. In contrast to SOL the MyHC type 1 isoform was not detectable in masticatory muscle tissues of control and mdx mice. In TEM and TON of mdx the MyHC type 2b and type 2x were significantly down regulated. We found a muscle specific lower content of GSH in mdx mice compared to controls.
Conclusion: These observations suggest that mdx masticatory muscles are differentially affected by the disease process. However, the observed down regulation of the MyHC isoforms may be responsible for the functional misbalance of masticatory muscles in DMD and could be causing dentomorphological changes.