Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China.
Center for TMD & Orofacial Pain, Peking University School & Hospital of Stomatology, Beijing, China.
J Oral Rehabil. 2022 Feb;49(2):207-218. doi: 10.1111/joor.13211. Epub 2021 Jun 7.
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.
To explore the involvement of RVM astrocytes in PEOI-induced oro-facial hyperalgesia or its maintenance following REOI.
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.
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.
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.
延髓头端腹内侧区（RVM）中的星形胶质细胞有助于下行性疼痛调节，但它们在持续实验性牙咬合干扰（PEOI）引起的口面部疼痛或去除 EOI 后（REOI）的维持中的作用尚不清楚。
探讨 RVM 星形胶质细胞在 PEOI 诱导的口面部痛觉过敏或 REOI 后维持中的作用。
雄性大鼠随机分为五组：假手术 EOI、PEOI 术后第 6 天和第 14 天（PEOI 6 d 和 PEOI 14 d）、REOI 术后第 3 天（REOI 3 d）和第 8 天（REOI 8 d）。在 RVM 星形胶质细胞缝隙连接阻滞剂 carbenoxolone（CBX）微注射前后，记录头部退缩阈值（HWT）和 RVM ON-或 OFF-细胞的活性。用胶质纤维酸性蛋白（GFAP）免疫组织化学标记 RVM 星形胶质细胞，并进行半定量分析。
持续的实验性牙咬合干扰引起的口面部痛觉过敏，表现为 HWT 降低，在 EOI 放置后第 3 天的 REOI 部分得到抑制，但在第 8 天则不然。只有在 EOI 放置后第 8 天的 REOI 组中，才会出现 GFAP 染色面积增加，而在该组中，CBX 可抑制维持性痛觉过敏；CBX 对 PEOI 14 d 组的痛觉过敏无抑制作用。OFF 细胞的活动没有变化，但 ON 细胞的自发活动和反应明显增强，在 EOI 放置后第 8 天的 REOI 组中，这些反应可被 CBX 抑制。
RVM 星形胶质细胞可能不参与 PEOI 诱导的口面部痛觉过敏或早期 REOI 抑制痛觉过敏，但参与晚期 REOI 对口面部痛觉过敏的维持。
