title: Bilateral increases in ERK activation at the spinomedullary junction region by acute masseter muscle injury during temporomandibular joint inflammation in the rats.
abstract: We determined the role of persistent monoarthritis of temporomandibular joint region (TMJ) on bilateral masseter muscle (MM) nociception in male rats using orofacial nocifensive behaviors, phosphorylated extracellular signal-regulated kinase and Fos induction at the trigeminal subnucleus caudalis/upper cervical spinal cord (Vc/C2) region in response to formalin injection to the MM region. TMJ inflammation was induced by local injection of CFA into the left TMJ region. Orofacial nocifensive behaviors evoked by formalin injection ipsilateral or contralateral to the TMJ inflammation appeared to be increased at 1-14 days or at 1, 10 and 14 days after induction of TMJ inflammation, respectively, while increases in behavioral duration were seen mainly in the late phase rather than the early phase. The number of pERK positive cells was investigated in superficial laminae at the Vc/C2region at 3, 10, 20, 60 and 80 min after MM stimulation with formalin at 14 days after TMJ inflammation. TMJ-inflamed rats displayed greater responses of pERK expression by the ipsilateral MM stimulation at 3-60 min, while contralateral MM stimulation increased pERK expression at 3, 10 and 20 min compared to non-CFA rats. Fos expression by MM stimulation was increased at 14 days after induction of TMJ inflammation regardless of the affected side. These findings showed that persistent TMJ inflammation for 10 and 14 days is sufficient to enhance MM nociception indicated by behaviors and neural responses in superficial laminae at the Vc/C2region.
authors.affiliation: Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori Chuo-ku, Niigata City, 951-8514, Niigata, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kurose
authors.affiliation: Department of Physiology, Wakayama Medical University, Wakayama City, Wakayama, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Imbe
authors.affiliation: Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori Chuo-ku, Niigata City, 951-8514, Niigata, Japan.|Division of Oral and Maxillofacial Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakatani
authors.affiliation: Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori Chuo-ku, Niigata City, 951-8514, Niigata, Japan.|General Dentistry Clinical Education Unit, Niigata University Medical and Dental Hospital, Niigata City, Niigata, Japan.
authors.forename: Mana
authors.initials: M
authors.lastname: Hasegawa
authors.affiliation: General Dentistry Clinical Education Unit, Niigata University Medical and Dental Hospital, Niigata City, Niigata, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Division of Oral and Maxillofacial Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata, Japan.
authors.forename: Ritsuo
authors.initials: R
authors.lastname: Takagi
authors.affiliation: Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori Chuo-ku, Niigata City, 951-8514, Niigata, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Yamamura
authors.affiliation: Department of Physical Therapy, Osaka Yukioka College of Health Science, Ibaraki City, Osaka, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Senba
authors.affiliation: Division of Oral Physiology, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-Dori Chuo-ku, Niigata City, 951-8514, Niigata, Japan. okamoto12@dent.niigata-u.ac.jp.|Department of Physiology, Wakayama Medical University, Wakayama City, Wakayama, Japan. okamoto12@dent.niigata-u.ac.jp.
authors.forename: Keiichiro
authors.identifier: 0000-0002-3519-9561
authors.initials: K
authors.lastname: Okamoto
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005557:Formaldehyde / Q000009:adverse effects; D005620:Freund's Adjuvant / Q000633:toxicity; D007839:Functional Laterality / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007249:Inflammation / Q000150:complications*; D008297:Male; D008406:Masseter Muscle / Q000473:pathology; D009135:Muscular Diseases / Q000209:etiology* / Q000473:pathology; D009434:Neural Pathways / Q000378:metabolism*; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000139:chemically induced / Q000150:complications*; D013997:Time Factors; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D005557:Formaldehyde; D005620:Freund's Adjuvant; D016761:Oncogene Proteins v-fos; D019892:eIF-2 Kinase
keywords: Bilateral hyperalgesia; Orofacial formalin test; Pain; Trigeminal subnucleus caudalis; pERK