International College of Football, Tongji University, Shanghai, China.
Department of Sport Rehabilitation, School of Kinesiology, Shanghai University of Sport, Shanghai, China.
Neurosci Lett. 2019 Oct 15;711:134417. doi: 10.1016/j.neulet.2019.134417. Epub 2019 Aug 6.
Myofascial trigger points (MTrPs) are defined as hyperirritable spots in a palpable taut band (TB) of skeletal muscle fibers. Knowing the formation and location of MTrPs is a great help to prevent their development and inactivate existing MTrPs. This study aimed to obtain new evidence that myofascial trigger spots (MTrSs), which are similar to human MTrPs, are found in dysfunctional motor endplates by observing the morphological characteristics of muscles and changes in biochemical substances. A total of 32 male Sprague Dawley rats were randomly divided into four groups: two control groups (i.e., C1 and C2) and two model groups (i.e., M1 and M2). C1 and M1 were used for acetylcholine (ACh) content measurement, while C2 and M2 were utilized for acetylcholinesterase (AChE) staining. In the model groups, blunt striking injury was induced and eccentric exercise was applied to the left gastrocnemius for 8 weeks. After 1 month, spontaneous electrical activity(SEA), AChE optical density (OD), muscle fiber diameter, and ACh content were measured. The results showed that extensive abnormal endplate noise (aEPN), including positive neurons, fibrillation potentials, fasciculation potential, and high amplitude (endplate spikes [EPS]), is present at MTrSs in M1. Quantitative electromyography results showed that the amplitudes of aEPN and frequency of EPS in M1 were significantly higher than those of C1. The ACh content of MTrSs in M1 was significantly higher than that in C1. The AChE OD value of M2 was significantly lower than that of C2. In addition, the diameter of the muscle fibers in the AChE-stained area was longer in M2 than in C2. In conclusion, MTrSs formed at the motor endplate with a larger diameter of muscle fibers. Excessive ACh release and decreased AChE activity at MTrSs stimulated muscle action potential and muscle contraction.
肌筋膜触发点（MTrPs）被定义为可触及的骨骼肌纤维紧张带（TB）中的高敏点。了解 MTrPs 的形成和位置对于防止其发展和使现有的 MTrPs 失活非常有帮助。本研究旨在通过观察肌肉的形态特征和生化物质的变化，获得新的证据，证明类似于人类 MTrPs 的肌筋膜触发点（MTrSs）存在于功能失调的运动终板中。总共 32 只雄性 Sprague Dawley 大鼠被随机分为四组：两组对照组（即 C1 和 C2）和两组模型组（即 M1 和 M2）。C1 和 M1 用于测量乙酰胆碱（ACh）含量，而 C2 和 M2 用于乙酰胆碱酯酶（AChE）染色。在模型组中，对左腓肠肌进行钝击伤和偏心运动，持续 8 周。1 个月后，测量自发电活动（SEA）、AChE 光密度（OD）、肌纤维直径和 ACh 含量。结果显示，M1 中的 MTrSs 存在广泛的异常终板噪声（aEPN），包括阳性神经元、纤颤电位、束颤电位和高振幅（终板棘波[EPS]）。定量肌电图结果显示，M1 中 aEPN 的振幅和 EPS 的频率明显高于 C1。M1 中 MTrSs 的 ACh 含量明显高于 C1。M2 的 AChE OD 值明显低于 C2。此外，AChE 染色区的肌纤维直径在 M2 中比在 C2 中更长。总之，MTrSs 形成于具有较大肌纤维直径的运动终板上。MTrSs 处过量的 ACh 释放和 AChE 活性降低刺激肌肉动作电位和肌肉收缩。
