The Laryngoscope · 2018
Social isolation alters ultrasonic vocalizations but not thyroarytenoid neuromuscular junctions in old rats.
СтатьяПоддержка NIH: внешняя программаНазвание и аннотация: Перевод в очереди
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Johnson Aaron M
Аннотация
OBJECTIVE: Age-related muscle atrophy of the laryngeal muscles contributes to presbyphonia. Remodeling of the neuromuscular junction is one aspect underlying age-related muscle atrophy. Although muscle disuse has been shown to exacerbate age-related neuromuscular changes in the limb muscles, it is unknown if reduced vocal use has a similar effect in the laryngeal muscles. The objective of this study was to examine the use of social isolation as a novel method to reduce vocal use in old rats-and the impact of that reduced vocal use on ultrasonic vocalization acoustics and neuromuscular junction morphology in the thyroarytenoid muscle.
STUDY DESIGN: Animal group comparison.
METHODS: Old F344/BN rats (31 months of age) were socially isolated (n = 8) or communally housed (n = 8) for 8 weeks. Effect of housing condition on ultrasonic vocalization acoustics was assessed by calculating the changes in vocalization fundamental frequency and amplitude from baseline to 8 weeks. Neuromuscular junction morphology was measured in the lateral and medial portions of the thyroarytenoid muscle at the conclusion of the experiment.
RESULTS: Vocalization amplitude decreased by a mean of -4.4 dB (standard deviation [SD], 4.49) after social isolation, whereas amplitude increased by a mean of 5.7 dB (SD, 5.07) in the communally housed rats (P = 0.002). There was no significant difference in the change in fundamental frequency between groups. Furthermore, there were no group differences in any measure of neuromuscular junction morphology.
CONCLUSION: These results suggest that neuromuscular junctions in the thyroarytenoid muscle of old rats are unaffected by 8 weeks of social isolation, despite functional changes in vocalizations.
LEVEL OF EVIDENCE: NA Laryngoscope, 129:E9-E14, 2019.
STUDY DESIGN: Animal group comparison.
METHODS: Old F344/BN rats (31 months of age) were socially isolated (n = 8) or communally housed (n = 8) for 8 weeks. Effect of housing condition on ultrasonic vocalization acoustics was assessed by calculating the changes in vocalization fundamental frequency and amplitude from baseline to 8 weeks. Neuromuscular junction morphology was measured in the lateral and medial portions of the thyroarytenoid muscle at the conclusion of the experiment.
RESULTS: Vocalization amplitude decreased by a mean of -4.4 dB (standard deviation [SD], 4.49) after social isolation, whereas amplitude increased by a mean of 5.7 dB (SD, 5.07) in the communally housed rats (P = 0.002). There was no significant difference in the change in fundamental frequency between groups. Furthermore, there were no group differences in any measure of neuromuscular junction morphology.
CONCLUSION: These results suggest that neuromuscular junctions in the thyroarytenoid muscle of old rats are unaffected by 8 weeks of social isolation, despite functional changes in vocalizations.
LEVEL OF EVIDENCE: NA Laryngoscope, 129:E9-E14, 2019.