三叉神经参与牙髓炎症及痛觉过敏的实验研究

Experimental Study of Trigeminal Nervous System Involved in the Pulpitis and Hyperalgesia

目的:观察牙髓炎大鼠三叉神经节初级感觉神经元及牙周组织中疼痛及炎症相关因子的表达变化,探讨三叉神经参与牙髓病理改变及炎性疼痛的信号调节作用。方法:建立完全弗氏佐剂诱发的大鼠牙髓炎痛敏模型,应用免疫荧光标记法观察牙髓炎症及炎性痛敏过程神经元细胞体中CGRP的动态表达,检测牙髓及牙周组织中TNF-α的表达与分布。结果:完全弗氏佐剂诱发大鼠急性牙髓炎症,镜下可见牙髓成牙本质细胞层排列紊乱、空泡性变,根周牙槽骨骨髓腔内出现大量弥散性炎细胞浸润灶。炎症刺激24h后,三叉神经节初级感觉神经元CGRP表达明显增强,1周后显著性减少;牙周组织中TNF-α于牙髓炎24h后表达明显增加,持续至炎症刺激1周后。结论:三叉神经系统通过调节CGRP的表达参与牙髓的炎症及痛觉过敏过程;TNF-α不仅在牙髓炎的发生发展过程中具有重要的炎症介导作用,并且在炎性疼痛的发展和维持中起关键的作用。

Objective： To investigate the changes of factors associated with pain and inflammation in primary sen sory neurons in trigeminal ganglion and periodontal tissues in rat with pulpitis, under normal and inflammatory con- ditions of pulpitis and to elucidate the potential roles of trigeminal nervous system that involved in the histopatholog- ical developments of pulpitis and inflammatory pain. Methods： A rat animal--model with acute pulpitis was induced by Freundrs adjuvant complete （CFA）. Immunofluorescence was used to indicate the expression of CGRP and TNF -α in the trigeminal ganglion neurons and periodontal tissues. Results： Acute pulpitis was induced by CFA. At 24 hour post--inflammation, irregular arrangements and vacuolar degeneration of the odontoblastic layer appeared in the grown pulp and mass of diffused inflammatory cells were found in the periodontal tissues. The expression of CGRP in the TG primary sensory neurons and their axons increased immediately and decreased significantly at 1 week post--inflammation. Meanwhile, the expression of TNF-α was obvious in the periodontal tissues at 24 hours post--inflammation and lasted to 1 week after pulpitis. Conclusion： The trigelninal nervous system may participate in the histopathological development of pulpitis and hyperalgesia by regulating the expression of CGRP. TNF-α not only positively associated with the developments and progression of pulpitis, but also played a key role in the induc- tion and maintenance of inflammatory pain.