Quantitative Analysis of Myosin Heavy Chain Expression Change in Laryngeal Muscle after Irradiation in Rats

Abstract

PurposeRadiotherapy for head and neck cancer does not impair the voice quality as much as laser treatment or surgery, but it can induce muscle wasting and fibrosis and symptoms of dry mouth. We investigated the effect of irradiation on the myosin heavy chain (MyHC) expression in laryngeal muscles.Materials and MethodsRats were irradiated with one dose of 10, 15, 20, 25, 30, or 35 Gy and other rats were irradiated with 20 Gy. The thyroarytenoid (TA), posterior cricoarytenoid (PCA), and cricothyroid (CT) muscles were subjected to reverse transcription-polymerase chain reaction (RT-PCR).ResultsTwo weeks after irradiation with 10, 15, or 20 Gy, all the MyHC type expressions had decreased in a dose-dependent manner in the TA, PCA, and CT muscles, and especially the expression of MyHC IIa decreased much more than the expressions of the other MyHC isoforms in all muscles. In the 20 Gy-irradiated rats, almost all the MyHC isoform expressions declined over 12 weeks in the TA, PCA, and CT muscles, except for the MyHC I expression in the PCA and CT muscle. The MyHC IIa expression was markedly decreased in all the muscles.ConclusionThe laryngeal muscles responded differently to radiation, but they showed a time-dependent and long-lasting decrease in the expressions of all the MyHC isoforms in the TA, PCA, and CT muscles. In particular, the expression of the MyHC IIa isoform in all the muscles may be more sensitive to irradiation than the expressions of the other MyHC isoforms.

The effects of concurrent chemoradiation therapy to the base of tongue in a preclinical model

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Impact of Irradiation on laryngeal hydration and lubrication in rat larynx

“…Animals were locally irradiated in the laryngeal region with the rest of the body shielded from the radiation field. The dose required for radiation‐induced laryngeal damage without compromising general health was calculated as previously described …”

“…The dose required for radiation-induced laryngeal damage without compromising general health was calculated as previously described. 16 Micromorphological Changes in the Laryngeal Mucosa After Irradiation Histopathological Examination. Five larynges were harvested for histological analysis after euthanasia at 3 months postirradiation from irradiated and unirradiated controls.…”