Department of Communication Sciences and Disorders, Goodnight Hall, 1975 Willow Drive, Madison, WI, 53706, United States; Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, K4/7 Clinical Sciences Center, 600 Highland Avenue, Madison, WI 53792, United States.
Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, K4/7 Clinical Sciences Center, 600 Highland Avenue, Madison, WI 53792, United States.
Arch Oral Biol. 2018 May;89:37-43. doi: 10.1016/j.archoralbio.2018.02.002. Epub 2018 Feb 8.
This study sought to examin effects of age and tongue exercise on the posterior digastric (opener) and the temporalis (closer). We hypothesized 1) age would result in differing morphological (cross sectional area) and biochemical (myosin heavy chain isoform) components of these muscles; 2) tongue exercise would result in coactivation of these muscles inducing a decrease in age-related differences between age groups.
Young adult (9 months) and old (32 months) Fischer 344 Brown Norway rats were randomized into a tongue exercise or control group. Post-training, posterior digastric and temporalis muscles were harvested and analyzed using: 1) Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) to assess percent myosin heavy chain (MyHC) content; 2) Immunohistochemical staining to determine cross sectional area (CSA).
A larger proportion of slowly contracting MyHC isoforms in the posterior digastric and temporalis muscles were found in old. No significant main effects for age or exercise in fiber size were found in posterior digastric muscle. An interaction between age and exercise for temporalis cross sectional area indicated the old exercise group had smaller average cross sectional area than all other groups. CONCLUSIONS FINDINGS: suggest that: 1) Increasing age induces biochemical changes in muscles of the jaw, specifically showing an increase the proportion of slower contracting MyHC isoforms; 2) Increasing age and tongue exercise induce a reduction in muscle fiber cross sectional area in the temporalis muscle only. However, continued study of these cranial muscle systems is warranted to better understand these changes that occur with age and exercise.
本研究旨在探讨年龄和舌肌运动对二腹肌（开口肌）和颞肌（闭口肌）的影响。我们假设 1）年龄会导致这些肌肉的形态（横截面积）和生化（肌球蛋白重链同工型）成分发生变化；2）舌肌运动可导致这些肌肉的共同激活，从而减少各年龄段之间的与年龄相关的差异。
将年轻成年（9 个月）和老年（32 个月）Fischer 344 褐家鼠随机分为舌肌运动组或对照组。训练后，采集二腹肌和颞肌并进行以下分析：1）十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）评估肌球蛋白重链（MyHC）含量百分比；2）免疫组织化学染色测定横截面积（CSA）。
老年组二腹肌和颞肌中收缩较慢的 MyHC 同工型比例较大。二腹肌纤维大小无明显年龄或运动主效应。颞肌横截面积的年龄与运动的交互作用表明，老年运动组的平均横截面积小于其他所有组。结论：这些发现表明：1）年龄的增长会引起咀嚼肌的生化变化，特别是收缩较慢的 MyHC 同工型比例增加；2）年龄的增长和舌肌运动仅会导致颞肌纤维横截面积减少。然而，需要进一步研究这些颅面肌肉系统，以更好地了解与年龄和运动相关的这些变化。
