Astrocytes in the rostral ventromedial medulla contribute to the maintenance of oro‐facial hyperalgesia induced by late removal of dental occlusal interference. (7th June 2021)

• Record Type: Journal Article
• Authors: Mo, Si‐Yi; Bai, Shan‐Shan; Xu, Xiao‐Xiang; Liu, Yun; Fu, Kai‐Yuan; Sessle, Barry J.; Cao, Ye; Xie, Qiu‐Fei
• Other Names: Fu Kai‐Yuan guestEditor.; Wang Kelun guestEditor.; Wang Mei‐Qing guestEditor.; Cao Ye guestEditor.
• Is Part Of: Journal of oral rehabilitation. Volume 49:Number 2(2022)
• Page Start: 207
• Page End: 218
• Publication Date: 2021-06-07
• Subjects: astrocyte -- carbenoxolone -- dental occlusal interference -- oro‐facial pain -- pain modulation -- rostral ventromedial medulla; Dentistry -- Periodicals; Prosthodontics -- Periodicals; 617
• DOI: 10.1111/joor.13211
• Languages: English
• ISSNs: 0305-182X

Abstract

Abstract: Background: Astrocytes in the rostral ventromedial medulla (RVM) contribute to descending pain modulation, but their role in oro‐facial pain induced by persistent experimental dental occlusal interference (PEOI) or following EOI removal (REOI) is unknown. Objective: To explore the involvement of RVM astrocytes in PEOI‐induced oro‐facial hyperalgesia or its maintenance following REOI. Methods: Male rats were randomly assigned into five groups: sham‐EOI, postoperative day 6 and 14 of PEOI (PEOI 6 d and PEOI 14 d), postoperative day 6 following REOI on day 3 (REOI 3 d) and postoperative day 14 following REOI on day 8 (REOI 8 d). The nociceptive head withdrawal threshold (HWT) and activities of RVM ON‐ or OFF‐cells were recorded before and after intra‐RVM astrocyte gap junction blocker carbenoxolone (CBX) microinjection. RVM astrocytes were labelled immunohistochemically with glial fibrillary acidic protein (GFAP) and analysed semi‐quantitatively. Results: Persistent experimental dental occlusal interference‐induced oro‐facial hyperalgesia, as reflected in decreased HWTs, was partially inhibited by REOI at day 3 but not at day 8 after EOI placement. Increased GFAP‐staining area occurred only in REOI 8 d group in which CBX could inhibit the maintained hyperalgesia; CBX was ineffective in inhibiting hyperalgesia in PEOI 14 d group. OFF‐cell activities showed no change, but the spontaneous activity and responses of ON‐cells were significantly enhanced that could be suppressed by CBX in REOI 8 d group. Conclusion: Rostral ventromedial medulla astrocytes may not participate in PEOI‐induced oro‐facial hyperalgesia or hyperalgesia inhibition by early REOI but are involved in the maintenance of oro‐facial hyperalgesia by late REOI.