Xu Xiaoxiang, Cao Ye, Ding Tingting, Fu Kaiyuan, Xie Qiufei
Department of Prosthodontics, Center for Oral and Jaw Functional Diagnosis, Treatment and Research, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Center for Temporomandibular Disorders & Orofacial Pain, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2016 Mar;51(3):176-81. doi: 10.3760/cma.j.issn.1002-0098.2016.03.010.
To explore the expression of purinergic p2X4 receptor (P2X4R) in trigeminal ganglion of rats after occlusal interference. Investigation of peripheral receptor mechanism of occlusal interference-induced masticatory muscle pain will aid the development of drug intervention against this condition.
Experimental occlusal interference was established by application of 0.4 mm metal crown to the upper right first molar of male Sprague-Dawley rats. Real-time PCR assay was used to investigate P2X4R mRNA level in trigeminal ganglion in rats with occlusal interference for 3, 7, 10 and 14 days and in control rats without occlusal interference (n=5 in each). Retrograde labelling combining immunofluorescence was performed to evaluate the percentage of P2X4R-positive cells in masseter afferent neurons (n=5 in each group). Graded concentrations of P2XR antagonist TNP-ATP (0.1, 10, 125, 250, 500 μmol/L) or saline (n=5 in each group) was administrated in right masseter and the mechanical sensitivity of bilateral masseters was measured before occlusal interference application, before the injection, and 30 min as well as 60 min after the injection.
Compared with control rats (P2X4R mRNA: right side: 1.00±0.26, left side: 0.94± 0.21; percentage of P2X4R-positive masseter afferents: right side: [64.3±6.3]%, left side: [67.7±5.8]%), the level of P2X4R mRNA in bilateral trigeminal ganglia (right side: 5.98±3.56; left side: 5.06±2.88) of rats with occlusal interference for 7 days up-regulated (P<0.01) and the percentage of P2X4R-positive masseter afferent neurons(right side: [81.7±1.5]%; left side: [82.9±2.3]%) increased (P<0.05). Local administration of 10, 125, 250, 500 μmol/L TNP-ATP increased the mechanical withdrawal threshold in masseter 30 min after injection, compared with those before injection (P<0.05).
Increased expression of trigeminal P2X4R involves in the development of occlusal interference-induced masseter hyperalgesia.
探讨咬合干扰后大鼠三叉神经节中嘌呤能P2X4受体（P2X4R）的表达。研究咬合干扰诱导咀嚼肌疼痛的外周受体机制将有助于开发针对这种情况的药物干预措施。
通过在雄性Sprague-Dawley大鼠的右上第一磨牙上施加0.4mm金属冠建立实验性咬合干扰。采用实时PCR检测法，研究咬合干扰3、7、10和14天的大鼠及无咬合干扰的对照大鼠（每组n = 5）三叉神经节中P2X4R mRNA水平。进行逆行标记结合免疫荧光，以评估咬肌传入神经元中P2X4R阳性细胞的百分比（每组n = 5）。在右侧咬肌中给予不同浓度梯度的P2XR拮抗剂TNP-ATP（0.1、10、125、250、500μmol/L）或生理盐水（每组n = 5），并在施加咬合干扰前、注射前、注射后30分钟和60分钟测量双侧咬肌的机械敏感性。
与对照大鼠相比（P2X4R mRNA：右侧：1.00±0.26，左侧：0.94±0.21；P2X4R阳性咬肌传入纤维百分比：右侧：[64.3±6.3]%，左侧：[67.7±5.8]%），咬合干扰7天的大鼠双侧三叉神经节中P2X4R mRNA水平上调（右侧：5.98±3.56；左侧：5.06±2.88）（P<0.01），P2X4R阳性咬肌传入神经元的百分比增加（右侧：[81.7±1.5]%；左侧：[82.9±2.3]%）（P<0.05）。与注射前相比，局部注射10、125、250、500μmol/L TNP-ATP可在注射后30分钟提高咬肌的机械退缩阈值（P<0.05）。
三叉神经P2X4R表达增加参与了咬合干扰诱导的咬肌痛觉过敏的发生。
