Characteristics of Early Internal Laryngeal Muscle Atrophy After Recurrent Laryngeal Nerve Injuries in Rats
Editor's Note: This Manuscript was accepted for publication on October 15, 2020.
This work was funded by a Beijing Natural Science Foundation (Grants No. 7172051).
This work was done in the Key Laboratory of Otolaryngology–Head and Neck Surgery, Ministry of Education of China, Beijing, China.
The authors have no funding, financial relationships, or conflicts of interest to disclose.
Abstract
Objectives/Hypothesis
The present study investigated the characteristics of early internal laryngeal muscle atrophy in recurrent laryngeal nerve injury (RLNI) rats.
Study Design
To observe the characteristics of early internal laryngeal muscle atrophy post RLNI.
Methods
Rats were divided into three groups: sham-operated control group (n = 20), recurrent laryngeal nerve transverse injury group (RLNTI, n = 50), and recurrent laryngeal nerve blunt contusion group (RLNBC, n = 50). Five weeks after RLNI, certain rats were sacrificed weekly, and their laryngeal tissues were harvested. The atrophic features of internal laryngeal muscles were detected using hematoxylin and eosin. NF-κB and MuRF-1 levels were tested using IHC.
Results
The atrophic degree and fibrosis of thyroarytenoid, posterior cricoarytenoid, and lateral cricoarytenoid muscles were related to the type of RLNI. The average myofiber cross-sectional areas increased before an obvious decrease in the RLNTI and RLNBC groups. Muscle recovery occurred in the RLNBC group starting 4 weeks after RLNI, but only a weak trend was observed in the RLNTI group in the 5th week. During the muscle atrophy process, MuRF-1 and NF-κB were upregulated early and were maintained at a high level, which showed a trend similar to muscle atrophy. However, NF-κB expression was opposite to MuRF-1 expression and muscle atrophy when the muscles recovered.
Conclusion
The atrophy degree of internal laryngeal muscles was associated with the type of RLNI. The NF-κB/MuRF-1 signaling pathway was involved in internal laryngeal muscle atrophy after RLNI, which is different from skeletal muscle after denervation.
Level of Evidence
NA Laryngoscope, 131:E1256–E1264, 2021
