Department of Neurosurgery, University of Iowa, USA.
Department of Surgery, University of Wisconsin-Madison, Madison, WI, USA; Department of Communication Sciences and Disorders, University of Wisconsin, Madison, USA.
Arch Oral Biol. 2023 Nov;155:105779. doi: 10.1016/j.archoralbio.2023.105779. Epub 2023 Aug 1.
To investigate potential effects of sex on voluntary tongue strength, evoked twitch and tetanic tension, speed of contraction, and muscle fiber cross-sectional area in the muscles of the rat tongue. Additionally, we aimed to determine whether estrous cycle stage impacts any of the dependent variables as a pilot investigation into the use of female rats in a model of tongue exercise and aging.
Fischer 344-Brown Norway male and female rats in two age groups (16 middle-aged, 16 young-adult) were trained to use a tongue force operandum. Tongue muscle contraction, myosin heavy chain (MyHC) composition, and cross section area of the genioglossus and styloglossus muscles were examined. Vaginal lavage determined estrous cycle stage of the female rats daily.
The female group had significantly lower evoked twitch and tetanic tension, longer contraction times, and a smaller proportion of MyHC type IIa and MyHC type IIx in the styloglossus muscle. There was no significant sex effect in maximal voluntary tongue force (MVTF) despite a significant weight difference between the male and female groups. There were no significant age or sex effects in the genioglossus. Estrous cycle stage did not have a significant effect on any of the dependent variables.
Sex and age both have a significant effect on tongue muscle structure and physiology. While the female group showed reduced contraction speed and maximal twitch and tetanic tension relative to the male group, differences in muscle morphology appeared to vary by muscle.
研究性别的潜在影响对大鼠舌肌的自愿舌力、诱发的抽搐和强直性张力、收缩速度以及肌肉纤维横截面积的影响。此外，我们旨在确定发情周期阶段是否会影响任何因变量，这是对雌性大鼠在舌运动和衰老模型中应用的初步研究。
16 只中年和 16 只青年的 Fischer 344-棕色挪威雄性和雌性大鼠被训练使用舌力操作器。检查了舌肌收缩、肌球蛋白重链（MyHC）组成以及颏舌肌和茎突舌骨肌的横截面积。阴道冲洗每天确定雌性大鼠的发情周期阶段。
尽管雄性和雌性组之间的体重存在显著差异，但女性组的诱发抽搐和强直性张力明显较低，收缩时间更长，且颏舌肌中的 MyHC 类型 IIa 和 MyHC 类型 IIx 比例较小。最大自愿舌力（MVTF）没有显著的性别效应。在颏舌肌中没有明显的年龄或性别效应。发情周期阶段对任何因变量均无显著影响。
性别和年龄对舌肌结构和生理学均有显著影响。尽管女性组相对于雄性组表现出收缩速度降低以及最大抽搐和强直性张力降低，但肌肉形态的差异似乎因肌肉而异。
