School of Dentistry, Universidad Científica del Sur, Lima, Peru.
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Sci Rep. 2023 Apr 17;13(1):6245. doi: 10.1038/s41598-023-32921-w.
The aim of the study was to address the genioglossus muscle physiological and histological changes after unilateral nasal obstruction in growing rats. Fifty-four 6-day-old male Wistar albino rats were randomly divided into control (n = 27) and experimental (n = 27) groups. Unilateral nasal obstruction was performed at 8 days old. Contractile properties of the genioglossus whole muscle were measured at 5-, 7- and 9-week-old, including the twitch and tetanic forces, contraction time, half-decay time, and fatigue index. The histological characteristics of the genioglossus were also evaluated at 5-, 7- and 9-week-old, analyzing the myosin heavy chain composition of the slow, fast, IIa and IIb muscle fiber type, by measuring the number, rate, diameter and cross-sectional area. The maximal twitch force, and tetanic force at 60 Hz and 80 Hz force was significantly increased at all ages after nasal obstruction. The fatigue index was decreased at 5 weeks-old after nasal obstruction. The diameter and cross-sectional area of the fast, IIa and IIb muscle fiber types were increased at 7 and 9 weeks after nasal obstruction, while only the diameter of IIa type and cross-sectional area of IIb type were increased at 5 weeks-old after nasal obstruction. Nasal obstruction during growth affects the whole genioglossus muscle contractile properties and histological characteristics, increasing its force, the diameter and area of its muscle fibers. These changes in the genioglossus muscle may affect the normal growth, development and function of the craniofacial complex.
本研究旨在探讨单侧鼻腔阻塞对生长期大鼠颏舌肌的生理和组织学变化。将 54 只 6 日龄雄性 Wistar 白化大鼠随机分为对照组（n = 27）和实验组（n = 27）。在 8 日龄时进行单侧鼻腔阻塞。在 5、7 和 9 周龄时测量颏舌肌整体肌肉的收缩性能，包括收缩力、强直力、收缩时间、半衰减时间和疲劳指数。在 5、7 和 9 周龄时还评估了颏舌肌的组织学特征，通过测量慢肌、快肌、IIa 和 IIb 肌纤维类型的肌球蛋白重链组成，分析了慢肌、快肌、IIa 和 IIb 肌纤维类型的数量、比例、直径和横截面积。在鼻腔阻塞后所有年龄，最大收缩力和强直力在 60 Hz 和 80 Hz 时均显著增加。在鼻腔阻塞后 5 周时疲劳指数降低。在鼻腔阻塞后 7 和 9 周时，快肌、IIa 和 IIb 肌纤维类型的直径和横截面积增加，而在鼻腔阻塞后 5 周时仅 IIa 型的直径和 IIb 型的横截面积增加。生长过程中的鼻腔阻塞会影响颏舌肌的整体收缩性能和组织学特征，增加其力、纤维的直径和面积。颏舌肌的这些变化可能会影响颅面复合体的正常生长、发育和功能。
