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Diaphragm muscle sarcopenia and neuromuscular junction morphology (863.6)
Author(s) -
Greising Sarah,
Stowe Jessica,
Mantilla Carlos,
Sieck Gary
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.863.6
Subject(s) - sarcopenia , denervation , neuromuscular junction , diaphragm (acoustics) , muscle fibre , fragmentation (computing) , medicine , anatomy , biology , skeletal muscle , neuroscience , ecology , physics , acoustics , loudspeaker
We recently determined the presence of sarcopenia in the diaphragm muscle (DIAm), specifically an age‐related reduction in force and muscle fiber cross‐sectional area, the latter being more pronounced at type IIx and/or IIb DIAm fibers. In limb muscles, age‐related changes at neuromuscular junctions (NMJs) include retraction of presynaptic terminals, disaggregation and fragmentation of the motor end‐plate. However, it is presently not clear whether aging impacts the morphology of DIAm NMJs. Adult male mice (n=14) at 6 and 24 months of age, representing survival rates of 100 and 75%, respectively, were used to examine DIAm NMJ structure, pre‐ and post‐synaptic morphology and overlap as measured in 3D by confocal microscopy (643 NMJs). No age related differences were evident in 2D planar area (mean: 328 µm 2 ) or complexity (i.e., fragmentation) of motor end‐plates. Pre‐ and post‐synaptic volumes were also similar across age groups. Evidence of partial or full denervation was present in ~6% of NMJs in both age groups. Thus, these results indicate that by 24 months of age, DIAm sarcopenia is not associated with evidence of ongoing denervation. Examination of earlier age groups will be necessary to rule out the contribution of NMJ denervation to DIAm sarcopenia given the loss of type IIx and/or IIb fibers by 24 months of age. Grant Funding Source : Supported by R01‐AG044615, T32‐HL105355, and the Mayo Clinic.