Department of Physical Therapy, Graduate Institute of Rehabilitation Science, China Medical University, Taichung 406040, Taiwan.
Kao-An Physical Medicine and Rehabilitation Clinic, Taichung 406040, Taiwan.
Int J Mol Sci. 2021 Sep 14;22(18):9906. doi: 10.3390/ijms22189906.
Masticatory myofascial pain (MMP) is one of the most common causes of chronic orofacial pain in patients with temporomandibular disorders. To explore the antinociceptive effects of ultra-low frequency transcutaneous electrical nerve stimulation (ULF-TENS) on alterations of pain-related biochemicals, electrophysiology and jaw-opening movement in an animal model with MMP, a total of 40 rats were randomly and equally assigned to four groups; i.e., animals with MMP receiving either ULF-TENS or sham treatment, as well as those with sham-MMP receiving either ULF-TENS or sham treatment. MMP was induced by electrically stimulated repetitive tetanic contraction of masticatory muscle for 14 days. ULF-TENS was then performed at myofascial trigger points of masticatory muscles for seven days. Measurable outcomes included maximum jaw-opening distance, prevalence of endplate noise (EPN), and immunohistochemistry for substance P (SP) and μ-opiate receptors (MOR) in parabrachial nucleus and c-Fos in rostral ventromedial medulla. There were significant improvements in maximum jaw-opening distance and EPN prevalence after ULF-TENS in animals with MMP. ULF-TENS also significantly reduced SP overexpression, increased MOR expression in parabrachial nucleus, and increased c-Fos expression in rostral ventromedial medulla. ULF-TENS may represent a novel and applicable therapeutic approach for improvement of orofacial pain induced by MMP.
咀嚼肌筋膜疼痛（MMP）是颞下颌关节紊乱患者慢性或颌面疼痛的最常见原因之一。为了探讨超低频经皮神经电刺激（ULF-TENS）对 MMP 动物模型中与疼痛相关的生物化学、电生理学和张口运动改变的镇痛作用，将 40 只大鼠随机均分为 4 组；即接受 ULF-TENS 或假处理的 MMP 动物，以及接受假处理的 MMP 动物或假处理的 sham-MMP 动物。MMP 通过咀嚼肌电刺激重复强直收缩诱导 14 天。然后在咀嚼肌肌筋膜触发点进行 ULF-TENS 治疗 7 天。可测量的结果包括最大张口距离、终板噪声（EPN）的发生率、臂旁核中 P 物质（SP）和 μ 阿片受体（MOR）的免疫组织化学以及头端腹内侧髓质中的 c-Fos。在 MMP 动物中，ULF-TENS 可显著改善最大张口距离和 EPN 的发生率。ULF-TENS 还显著减少了 SP 的过度表达，增加了臂旁核中的 MOR 表达，并增加了头端腹内侧髓质中的 c-Fos 表达。ULF-TENS 可能代表一种新颖且适用的治疗方法，可改善 MMP 引起的颌面疼痛。
