Effect of Aging on Tongue Protrusion Forces in Rats

Abstract

The purpose of this study was to ascertain the effect of aging on muscle contractile properties associated with tongue protrusion in a rat model. Fischer 344/Brown Norway hybrid rats, ten young (9 months old) and ten old (32 months old), were used to measure protrusive contractile properties. Results showed a significant reduction in tetanic forces in the old animals. The following measures of muscle contraction were not different between age groups: mean twitch contraction force, twitch contraction time, twitch contraction half-decay time, and a calculated measure of fatigability. In conclusion, aging influenced protrusive tongue muscle contractions in a rat model such that tetanic forces were reduced. The reduction of tetanus force may parallel findings in human subjects relative to isometric tongue force generation and may be associated with age-related disorders of swallowing.

Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

“…The transducer was oriented inferiorly to the rat to maximize the force vector during evoked protrusive tongue actions. Following a 45-min stabilization period, the medial branch of the hypoglossal nerve was supramaximally stimulated at 1.5 times the maximum twitch response (1 Hz rectangular-wave pulses, pulse width 0.1 ms), and protrusive muscle contractile properties were measured as described previously (10,45). Stimuli were delivered at 1 Hz to elicit a twitch contraction.…”

“…Two-way ANOVA was used to examine age effects, treatment effects, and interactions for muscle contractile property variables and the MHC isoform composition of the GG. Body weight was used as a covariate for analysis of maximum twitch tension and tetanic tension because body weight was found to correlate highly with these variables in prior studies (11,45). Pairwise comparisons were made between groups using Fisher's protected least significant difference tests.…”

“…Age-related changes in GG muscle structure and physiology have been noted in humans and in animal models (11,15,28,45,50,56,67,68,71,75). Exercise may serve as an effective remediation because recent studies have identified increased GG muscle contraction amplitudes with exercise, as measured with electromyography (EMG) (73,83,88).…”

Differential effects of amphetamine and GBR-12909 on orolingual motor function in young vs aged F344/BN rats

“…We and others have reported tongue motility (but not force) deficits in aged F344 (Stanford et al, 2003; Zhang et al, 2008) and F344/BN (Nagai et al, 2008; Zhang and Stanford, 2008; Zhang et al, 2008) rats. In these studies, aged rats that are trained to lick water from a force-sensing surface exhibited slower licking speed (licks/second) than their younger counterparts.…”

Comparison of the Craniofacial Muscles: A Unifying Hypothesis

“…In facial muscles, while the skin undergoes signi fi cant loss of elastin, the facial muscles themselves are normal (Lee et al 2011 ) . Aging changes in tongue muscles are quite interesting; aging retrusive tongue muscles do not show a decrement in overall contractile speed or force production, but signi fi cant changes in forces is seen in aging protrusive tongue muscles (Nagai et al 2008 ;Connor et al 2009 ) . The basis for this difference in unclear.…”