title: Synovial TRPV1 is upregulated by 17-β-estradiol and involved in allodynia of inflamed temporomandibular joints in female rats.
abstract: Women with reproductive capability are more likely to suffer from temporomandibular disorders (TMD), with orofacial pain as the most common complaint. In the past, we focused on the role of estradiol in TMD pain through the nervous system. In this study, we explored estradiol's influence on synoviocyte gene expressions involved in the allodynia of the inflamed TMJ. The influence of 17-β-estradiol on NGF and TRPV1 expression in TMJ synovium was determined in vivo and in vitro and analyzed by Western blot and real-time PCR. Complete Freund's adjuvant (CFA) injection into the TMJ was used to induce TMJ arthritis. Capsazepine served as a TRPV1 antagonist. Head withdrawal threshold was examined using a von Frey Anesthesiometer. We observed that estradiol upregulated the expressions of TRPV1 and NGF in a dose-dependent manner. In the primary cultured synoviocytes, TRPV1 was upregulated by lipopolysaccharide (LPS), estradiol, and NGF, while NGF antibodies fully blocked LPS and estradiol-induced upregulation of TRPV1. Activation of TRPV1 in the primary synoviocytes with capsaicin, a TRPV1 agonist, dose-dependently enhanced COX-2 transcription. Moreover, intra-TMJ injection of TRPV1 antagonist, capsazepine, significantly attenuated allodynia of the inflamed TMJ induced by intra-TMJ injection of CFA in female rats. This article presents a possible local mechanism for estradiol that may be involved in TMJ inflammation or pain in the synovial membrane through the pain-related gene TRPV1. This finding could potentially help clinicians understand the sexual dimorphism of TMD pain.
authors.affiliation: Laboratory of Molecular Biology and Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, China. Electronic address: kqwuyuwei@126.com.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Wu
authors.affiliation: Laboratory of Molecular Biology and Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Hao
authors.affiliation: Laboratory of Molecular Biology and Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, China.
authors.forename: Xiao-Xing
authors.initials: XX
authors.lastname: Kou
authors.affiliation: Laboratory of Molecular Biology and Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, China. Electronic address: kqyehuagan@bjmu.edu.cn.
authors.forename: Ye-Hua
authors.initials: YH
authors.lastname: Gan
authors.affiliation: Center for TMD & Orofacial Pain, Peking University School and Hospital of Stomatology, China. Electronic address: kqxcma@bjmu.edu.cn.
authors.forename: Xu-Chen
authors.initials: XC
authors.lastname: Ma
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005620:Freund's Adjuvant; D006930:Hyperalgesia / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D050916:TRPV Cation Channels / Q000378:metabolism*; D013704:Temporomandibular Joint / Q000378:metabolism*; D013705:Temporomandibular Joint Disorders / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D004958:Estradiol; D005620:Freund's Adjuvant; D020932:Nerve Growth Factor; D051546:Cyclooxygenase 2; C071423:capsazepine; D002211:Capsaicin
keywords: COX-2; Estradiol; NGF; Synoviocytes ;TRPV1