Kemp, John

Tongue-muscle associated behaviours (swallow, speech) are impaired in the elderly. In the Fischer 344 (F344) rat model of aging, hypoglossal MNs and intrinsic tongue muscle weakness and atrophy are evident. Here we evaluated young (6-months; n=6 rats) and old (24-months-old; n=6 rats) F344 rat longitudinal muscles for neuromuscular junction (NMJ) innervation. In 140 µm free floating sections, presynaptic components were labelled with synaptophysin and neurofilament. Postsynaptic acetylcholine receptors were labelled with α-Bungarotoxin. NMJs were imaged using confocal microscopy with presynaptic invasion of the postsynaptic endplate quantified (n=200 young NMJs, n=180 old NMJs). We found marked denervation of tongue NMJs in old age,. Our findings underpin the significant role that tongue dysfunction has in the increased risk of aspiration pneumonia and obstructive sleep apnea in the elderly. This study was supported by R56 HL166204 (MJF), R01 AG086136 (MJF) and AG44615 (GCS) from the NIH. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.