The effects of age on atrophy and recovery in denervated fiber types of the rat nasolabialis muscle.
The effects of age on atrophy and recovery in denervated fiber types of the rat nasolabialis muscle.
复制标题
年龄对大鼠鼻唇肌去神经纤维类型萎缩和恢复的影响。
DOI：
10.1002/ar.1092290202
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Vaughan,DW
中科院分区：
文献类型：
--
作者：
White,KK;Vaughan,DW
本研究探讨年龄增长对鼻唇肌纤维对去神经和再神经支配的反应的影响。鼻唇肌受面神经支配，负责动物大触须的拂动运动。在年轻成年（3个月）和中年（15个月）大鼠中，通过挤压面神经使头部一侧的肌肉失神经支配。在挤压后的特定日期，处死动物并孵育肌肉厚切片以证明细胞色素氧化酶活性，细胞色素氧化酶是一种线粒体酶，可区分红色、白色和中间纤维类型。使用光学显微镜形态测量方法评估萎缩和恢复的速率和程度，测量横纤维面积并与对侧对照侧的纤维进行比较。功能恢复时间存在年龄相关延迟，因为老年动物比年轻动物晚6天恢复正常搅拌行为。在两个年龄组中，白色和中间纤维萎缩程度最大，红色纤维萎缩程度最小。尽管不同类型的纤维对去神经支配的反应不同，但在每种纤维类型内，纤维萎缩的最大程度没有年龄差异。年龄差异确实存在于去神经反应的速率中，因为中年纤维始终显示出比年轻成人纤维更快速的显著萎缩。在恢复过程中，较老的纤维可能在其达到控制侧的纤维尺寸的能力方面受到限制。结果表明，通过中年，年龄增长的过程中增加鼻唇肌去神经支配的敏感性，但不改变最大程度的萎缩。失神经支配后至少2个月恢复到正常纤维大小的能力也与年龄有关。
This study investigates the effects of advancing age on responses of nasolabialis muscle fibers to denervation and reinnervation. The nasolabialis is innervated by the facial nerve and is responsible for the whisking movement of the animal's large vibrissae. In young adult (3‐month) and middle‐aged (15‐month) rats the muscle on one side of the head was denervated by crushing the facial nerve. At specific days postcrush, animals were sacrificed and thick sections of muscle were incubated to demonstrate cytochrome oxidase activity, a mitochondrial enzyme, which differentiated between red, white, and intermediate fiber types. The rate and extent of atrophy and recovery were evaluated using light microscope morphometric methods for which transverse fiber areas were measured and compared to fibers on the contralateral control side. There was an age‐related delay in the time of functional return since older animals resumed normal whisking behavior 6 days later than the younger animals. In both age groups, white and intermediate fibers atrophied to the greatest extent and red fibers showed least atrophy. Despite the different responses of the fiber types to denervation, there was no age difference in the maximum degree of fiber atrophy within each fiber type. Age differences did occur in the rate of the denervation response since the middle‐aged fibers consistantly showed a more rapid significant atrophy than the young adult fibers. During recovery, older fibers may be limited in their ability to attain the size of fibers on the control side. The results indicate that through middle age, the process of advancing age increases the susceptibility of the nasolabialis muscle to denervation but does not alter the maximum extent of atrophy. The ability to recover to normal fiber size, at least 2 months after denervation, is also age‐related.