Age-related effect of cell death on fiber morphology and number in tongue muscle.

INTRODUCTION: Multiple pathways may exist for age-related tongue muscle degeneration. Cell death is one mechanism contributing to muscle atrophy and decreased function. We hypothesized with aging, apoptosis, and apoptotic regulators would be increased, and muscle fiber size and number would be reduced in extrinsic tongue muscles.

METHODS: Cell death indices, expression of caspase-3 and Bcl-2, and measures of muscle morphology and number were determined in extrinsic tongue muscles of young and old rats.

RESULTS: Significant increases in cell death, caspase-3, and Bcl-2 were observed in all extrinsic tongue muscles along with reductions in muscle fiber number in old rats.

DISCUSSION: We demonstrated that apoptosis indices increase with age in lingual muscles and that alterations in apoptotic regulators may be associated with age-related degeneration in muscle fiber size and number. These observed apoptotic processes may be detrimental to muscle function, and may contribute to degradation of cranial functions with age. Muscle Nerve 57: E29-E37, 2018.