title: Myelinated Afferents Are Involved in Pathology of the Spontaneous Electrical Activity and Mechanical Hyperalgesia of Myofascial Trigger Spots in Rats.
abstract: Myofascial trigger points (MTrPs) are common causes for chronic pain. Myelinated afferents were considered to be related with muscular pain, and our clinical researches indicated they might participate in the pathology of MTrPs. Here, we applied myofascial trigger spots (MTrSs, equal to MTrPs in human) of rats to further investigate role of myelinated afferents. Modified pyridine-silver staining revealed more nerve endings at MTrSs than non-MTrSs (P < 0.01), and immunohistochemistry with Neurofilament 200 indicated more myelinated afferents existed in MTrSs (P < 0.01). Spontaneous electrical activity (SEA) recordings at MTrSs showed that specific block of myelinated afferents in sciatic nerve with tetrodotoxin (TTX) led to significantly decreased SEA (P < 0.05). Behavioral assessment showed that mechanical pain thresholds (MPTs) of MTrSs were lower than those of non-MTrSs (P < 0.01). Block of myelinated afferents by intramuscular TTX injection increased MPTs of MTrSs significantly (P < 0.01), while MPTs of non-MTrSs first decreased (P < 0.05) and then increased (P > 0.05). 30 min after the injection, MPTs at MTrSs were significantly lower than those of non-MTrSs (P < 0.01). Therefore, we concluded that proliferated myelinated afferents existed at MTrSs, which were closely related to pathology of SEA and mechanical hyperalgesia of MTrSs.
authors.affiliation: Department of Physical Medicine & Rehabilitation, Qilu Hospital of Shandong University, No. 107, Wenhuaxi Road, Jinan, Shandong 250012, China.
authors.forename: Fei
authors.identifier: 0000-0002-3821-1079
authors.initials: F
authors.lastname: Meng
authors.affiliation: Laboratory for Musculoskeletal Pain and Motor Control, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7, Building D3, 9220 Aalborg, Denmark.
authors.forename: Hong-You
authors.identifier: 0000-0001-8452-225X
authors.initials: HY
authors.lastname: Ge
authors.affiliation: Department of Physical Medicine & Rehabilitation, Qilu Hospital of Shandong University, No. 107, Wenhuaxi Road, Jinan, Shandong 250012, China.
authors.forename: Yong-Hui
authors.identifier: 0000-0001-6301-7449
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Department of Physical Medicine & Rehabilitation, Qilu Hospital of Shandong University, No. 107, Wenhuaxi Road, Jinan, Shandong 250012, China.
authors.forename: Shou-Wei
authors.identifier: 0000-0002-4222-3806
authors.initials: SW
authors.lastname: Yue