title: Evidence for the existence of nociceptors in rat thoracolumbar fascia.
abstract: Recently, the existence of nociceptive fibers in fascia tissue has attracted much interest. Fascia can be a source of pain in several disorders such as fasciitis and non-specific low back pain. However, little is known about the properties of fascia nociceptors and possible changes of the fascia innervation by nociceptors under pathological circumstances. In this histologic study, the density of presumably nociceptive fibers and free nerve endings was determined in the three layers of the rat TLF: inner layer (IL, covering the multifidus muscle), middle layer (ML) and outer layer (OL). As markers for nociceptive fibers, antibodies to the neuropeptides CGRP and SP as well as to the transient receptor potential vanilloid 1 (TRPV1) were used. As a pathological state, inflammation of the TLF was induced with injection of complete Freund's adjuvant. The density of CGRP- and SP-positive fibers was significantly increased in the inner and outer layer of the inflamed fascia. In the thick middle layer, no inflammation-induced change occurred. In additional experiments, a neurogenic inflammation was induced in the fascia by electrical stimulation of dorsal roots. In these experiments, plasma extravasation was visible in the TLF, which is clear functional evidence for the existence of fascia nociceptors. The presence of nociceptors in the TLF and the increased density of presumably nociceptive fibers under chronic painful circumstances may explain the pain from a pathologically altered fascia. The fascia nociceptors probably contribute also to the pain in non-specific low back pain.
authors.affiliation: Department of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim, Ruprecht-Karls-University Heidelberg, D 68167, Mannheim, Germany. Electronic address: siegfried.mense@medma.uni-heidelberg.de.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Mense
authors.affiliation: Department of Neurophysiology, Center for Biomedicine and Medical Technology Mannheim, Ruprecht-Karls-University Heidelberg, D 68167, Mannheim, Germany. Electronic address: ulrich.hoheisel@medma.uni-heidelberg.de.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hoheisel
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000276:immunology; D004195:Disease Models, Animal; D005205:Fascia / Q000276:immunology / Q000294:innervation* / Q000503:physiopathology*; D005208:Fasciitis; D007249:Inflammation / Q000503:physiopathology*; D008297:Male; D009619:Nociceptors / Q000276:immunology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013373:Substance P / Q000276:immunology; D050916:TRPV Cation Channels / Q000378:metabolism
chemical_list: D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D013373:Substance P; D015740:Calcitonin Gene-Related Peptide
keywords: Fascia nociceptors; Fasciitis; Inflammation; Neurogenic inflammation; Non-specific low back pain