Validation of the FVB/N-Tg(HSA* LR)20bCath mice of myotonic dystrophy using swallowing function assessment, histology, and immunofluorescence analysis

Myotonic dystrophy is associated with dysphagia, which can lead to severe complications such as aspiration pneumonia and choking. However, few histopathological studies on dysphagia in myotonic dystrophy have been conducted. In this study, we aimed to validate the FVB/N-Tg(HSA*LR)20bCath mice for studying dysphagia associated with myotonic dystrophy, using videofluoroscopic swallowing study, histological analysis, and immunofluorescence analysis. Videofluoroscopic swallowing study, revealed significant abnormalities during the pharyngeal swallowing phase of swallowing in HSA LR20b mice, including increased pharyngeal residue area and prolonged pharyngeal transit time, suggesting that this mouse model was a valuable tool for studying dysphagia in myotonic dystrophy. These findings might represent a characteristic swallowing pattern in myotonic dystrophy. Histological analysis demonstrated marked variability in muscle fiber size and a high frequency of central nuclei. Additionally, decreased expression of chloride channel 1 was observed in the masseter muscle, suggesting the presence of myotonia. Collectively, these findings provide a foundation for further research into the complex mechanisms underlying myotonic dystrophy associated dysphagia and may inform the development of future treatment strategies.