Department of Otorhinolaryngology, Institute of Health Science, College of Medicine, Gyeongsang National University, 90 Chilam-dong, Jinju 660-702, Korea.
Yonsei Med J. 2011 Jan;52(1):158-64. doi: 10.3349/ymj.2011.52.1.158.
Radiotherapy 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.
Rats 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).
Two 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.
The 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.
头颈部癌症的放射治疗对嗓音质量的损害不如激光治疗或手术大，但会引起肌肉萎缩和纤维化以及口干症状。我们研究了放射治疗对喉肌肌球蛋白重链（MyHC）表达的影响。
大鼠接受单次 10、15、20、25、30 或 35Gy 照射，另一些大鼠接受 20Gy 照射。对甲杓肌（TA）、环杓后肌（PCA）和环甲肌（CT）进行反转录-聚合酶链反应（RT-PCR）。
在接受 10、15 或 20Gy 照射后 2 周，TA、PCA 和 CT 肌肉中的所有 MyHC 型表达均呈剂量依赖性下降，尤其是 IIa 型 MyHC 的表达下降幅度大于所有肌肉中的其他 MyHC 同工型。在接受 20Gy 照射的大鼠中，12 周内，TA、PCA 和 CT 肌肉中的几乎所有 MyHC 同工型表达均下降，除了 PCA 和 CT 肌肉中的 MyHC I 表达。所有肌肉中的 MyHC IIa 表达明显减少。
喉肌对辐射的反应不同，但在 TA、PCA 和 CT 肌肉中，所有 MyHC 同工型的表达均呈时间依赖性和长期下降。特别是，所有肌肉中 IIa 型 MyHC 同工型的表达可能比其他 MyHC 同工型的表达对辐射更为敏感。
