Prosem Lecture: Bioenergetic Changes in Rat Tongue Muscles with Aging and Tongue Exercise

Julia Mordarski, M.S.
Ph.D. Student
Department of Surgery-Otolaryngology, UW-Madison
Department of Communication Sciences and Disorders, UW-Madison

Topic: Bioenergetic Changes in Rat Tongue Muscles with Aging and Tongue Exercise

Tongue muscle fatigue (reduction in force output after continued activation) may be associated with age-related dysphagia and decreased nutritional intake. However, the bioenergetic mechanisms underlying tongue muscle fatigue are unknown. Further, it is not known if tongue exercise promotes resistance to fatigue in tongue muscles. The purpose of this study was to examine changes in muscle fiber composition in the intrinsic tongue and measure energy storage and availability in an aging rat model of tongue exercise. We randomized 30 young adult (6 months) and 30 old (29 months) Fischer 344/Brown Norway rats into progressive-resistance tongue exercise or sham exercise groups. We examined the effects of age and tongue exercise on intrinsic tongue muscle myosin heavy chain (MyHC) isoform composition and MyHC IIb (Myh4) gene expression, glycogen content, glyceraldehyde-3-phosphate dehydrogenase (Gapdh) and citrate synthase (Cs) gene expression. We found a significant increase in the proportion of MyHC IIa and a decrease in MyHC IIb with age (p < 0.05), but no changes with exercise. Preliminary findings show no changes in bioenergetic properties with age or exercise. Our findings suggest that muscle fiber composition changes with age, but not bioenergetic properties and that these measures are not altered by tongue exercise.

Funding: T32 DC009401; R01 DC018071

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