Videofluoroscopic characterization of swallowing impairment in mouse models of amyotrophic lateral sclerosis and advanced aging

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The goal of this study was to establish a videofluoroscopic swallow study (VFSS) protocol for mice that permits identification of translational biomarkers of swallowing impairment in mouse models of human conditions. Animals tested included the SOD1-G93A mouse model of ALS and aged C57 mice, which we propose as a model of presbyphagia (age related swallowing impairment). A protocol was established using 49 mice divided into three groups: 16 aged C57 mice (18-24 months of age), 21 healthy young mice (4-8 months of age), and 12 SOD1-G93A end-stage mice. Videos were analyzed to quantify four swallow parameters: lick rate equivalent, number of licks (lick rate equivalent) per swallow, swallow rate, and interswallow interval. Results showed that aged C57 mice and SOD1-G93A mice licked significantly slower than healthy young controls. Aged C57 mice swallowed slower than both healthy young mice and SOD1 endstage mice. This study provides novel evidence that elderly C57 mice swallow and lick more slowly than healthy young mice, which validates this strain as a naturally occurring model of presbyphagia. Future research will identify additional swallow parameters that will permit better detection and characterization of dysphagia in mouse models of ALS and presbyphagia.