A senescence accelerated mouse model to study aging in the larynx

Objective: Age-related changes in the larynx lead to significant voice impairment and reduced quality of life. There is a need for aged animal models that have practical generation times to study the fundamental changes and new therapeutics for the aging voice. The senescence accelerated prone mouse strain (SAMP) animals experience rapid aging without any experimental manipulation. The main objective of this study was to demonstrate the use of senescence accelerated mice to study aging in the larynx.

Study design: Murine model.

Setting: Department of Animal Resources, Emory University.

Subjects and methods: Larynges from five senescence accelerated prone mice, five normal aging senescence resistant mice, and five C57BL/6 mice were harvested and processed for paraffin sections. Histomorphometry was performed for assessment of collagen and hyaluronic acid distribution. In addition, frozen laryngeal tissue was harvested for transcriptional and translational assessment of collagen-1, using real-time polymerase chain reaction with specific primers and Western blots. Myofibroblast assessment was performed by immunostaining for the presence of alpha-smooth muscle actin.

Results: The deposition of collagen increased at six months of age in the SAMP vocal fold, and the level of collagen-1 mRNA increased with age. The myofibroblast protein alpha-smooth muscle actin was also found at a higher concentration in the SAMP vocal tissue. In contrast, the levels of hyaluronic acid in the vocal folds of SAMP mice decreased with age when compared to age-matched C57BL/6 mice.

Conclusion: SAMP mice show accelerated, age-related changes in the vocal fold that were evident at as early as six months of age. The use of senescence accelerated mice offers promise as a model to study age-related laryngeal changes.