Nerve growth factor and glutamate increase the density and expression of substance P-containing nerve fibers in healthy human masseter muscles

• Published in: Scientific reports 2021-08, Vol.11 (1), p.15673-9, Article 15673
• Main Authors: Alhilou, Abdelrahman M., Shimada, Akiko, Svensson, Camilla I., Svensson, Peter, Ernberg, Malin, Cairns, Brian E., Christidis, Nikolaos
• Format: Article
• Language: English
• Subjects: 631/378; 631/378/1686; 631/378/2586; 631/378/3917; Adult; Female; Glutamic Acid - metabolism; Glutamic acid receptors (ionotropic); Growth factors; Humanities and Social Sciences; Humans; Injection; Male; Masseter muscle; Masseter Muscle - innervation; Masseter Muscle - metabolism; multidisciplinary; Muscles; N-Methyl-D-aspartic acid receptors; Nerve Fibers - metabolism; Nerve growth factor; Nerve Growth Factor - metabolism; Pain; Receptors, N-Methyl-D-Aspartate - metabolism; Science; Science (multidisciplinary); Sensory neurons; Substance P; Substance P - metabolism; Young Adult
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-95229-7

Nocifensive behavior induced by injection of glutamate or nerve growth factor (NGF) into rats masseter muscle is mediated, in part, through the activation of peripheral NMDA receptors. However, information is lacking about the mechanism that contributes to pain and sensitization induced by these substances in humans. Immunohistochemical analysis of microbiopsies obtained from human masseter muscle was used to investigate if injection of glutamate into the NGF-sensitized masseter muscle alters the density or expression of the NMDA receptor subtype 2B (NR2B) or NGF by putative sensory afferent (that express SP) fibers. The relationship between expression and pain characteristics was also examined. NGF and glutamate administration increased the density and expression of NR2B and NGF by muscle putative sensory afferent fibers (P