Effect of Dystrophin Deficiency on Selected Intrinsic Laryngeal Muscles of themdxMouse

Abstract

The SCA and the CT appear spared in dystrophin-deficient mouse models. These laryngeal muscles possess specializations that separate them from typical skeletal muscle. Considered in light of previous research, the CT and IA may represent transitional form of muscle, evidencing properties of typical and specialized skeletal muscle.

Laryngeal Muscle Response to Neuromuscular Diseases and Specific Pathologies

“…A similar pattern of slightly increased central nucleation in the absence of marked myo fi ber degeneration has been previously described in other craniofacial muscles known to be marginally affected by dystrophin de fi ciency (Muller et al 2001 ;Andrade et al 2000 ) . Fry et al ( 2010 ) also demonstrated that utrophin was not up-regulated or relocalized in the laryngeal muscles, indicating that utrophin regulation alone cannot explain muscle sparing. These fi ndings point to the continued need to search for a mechanism of laryngeal muscle sparing in dystrophin de fi ciency.…”

“…Findings by Fry et al ( 2010 ) also suggested that the CT and superior cricoarytenoid (SCA), the murine analog to the human interarytenoids (IA), are spared from the pathological consequences of dystrophin de fi ciency in the mdx mouse. These results parallel to those of earlier studies using the mdx mouse that showed sparing of the TA, PCA, and LCA muscles (Marques et al 2007 ;Thomas et al 2008 ) (Fig.…”

“…Yet, the results of other studies showing the CT's phenotype (e.g., metabolic pro fi le, general morphology, response to disease) as falling between that of specialized laryngeal muscle and that of prototypical limb muscle, point away from this conclusion. Considering the full body of research on the CT, Fry et al ( 2010 ) supported the depiction of the CT as a "blended" or phenotypically variant form of skeletal muscle and suggest that additional work is necessary to further characterize this critical laryngeal muscle. Given the collective results to date, it is suggested that phenotypical variation of ILMs may exist on a continuum, with some muscles (such as the TA and PCA) expressing a highly distinct nature that is clearly different from typical limb muscle and other related muscles (such as the IA and CT) demonstrating a more transitional form.…”

“…The results of the Fry et al ( 2010 ) study demonstrate that the IA, like the TA, PCA, and LCA possess unique cellular features that appear to imbue a resistance to the effects of dystrophin de fi ciency. When such fi ndings are considered in light of previous work by Tellis et al ( 2004 ) showing the IA to be phenotypically similar to limb muscle, it is possible that the IA may represent a phenotypic variant or "blended" muscle type, sharing properties of specialized craniofacial muscles and properties of typical limb muscle.…”