INTRODUCTION: Muscle fiber denervation increases with age and yet studies at the tissue level are sparse, due to the challenging nature of establishing the relative role of regeneration and denervation.

METHODS: Muscle biopsies were obtained from the vastus lateralis of 70 healthy male participants (72±6 yrs, range: 65-94 yrs). mRNA levels of acetylcholine receptors (AchR) were measured and sections were stained for embryonic (MHCe ) and neonatal (MHCn ) myosins, and Neural Cell Adhesion Molecule (NCAM).

RESULTS: MHCe + fibers were rare, while MHCn + and NCAM+ fibers were observed in all samples. Age (range 65-94 yr) was negatively associated with AchRγ mRNA.

DISCUSSION: Muscle from healthy older individuals expresses developmental myosins to varying degrees, but more than previous reports for young individuals. Along with the AchR correlations, we propose that these findings support the presence of neuromuscular junction destabilization, denervation and re-innervation in aging human skeletal muscle. This article is protected by copyright. All rights reserved.