慢性炎症痛引起DRG感觉神经元P2X3受体表达的改变

目的探讨脊髓背根神经节（dorsal root ganglia，DRG）P2X3受体参与大鼠足底慢性炎症痛相关的热痛觉过敏机制。方法 1）用行为学的研究方法，以大鼠右侧后脚掌注射松节油加石蜡（各占50％）0．1ml建立后脚掌慢性痛模型，用热测痛的方法测量后脚掌皮下注射松节油后的痛阈，每天1次，连续测15d。2）用免疫组织化学技术观察大鼠后脚掌慢性炎症后第2天和第7天，炎症侧脊髓背根神经节（L4—6）神经元中P2X，受体阳性细胞类型的分布变化；以及正常脊髓背根神经节（L4—6）神经元中P2X，受体阳性细胞类型的分布作为对照。结果1）炎症后大鼠后脚掌侧痛阈出现降低，在第2天痛阈达到最低，后逐渐恢复，14d后恢复正常痛阈值。2）正常大鼠P2X，主要表达于DRG的中小神经元上，炎症后DRG（L4—6），中小型P2X，受体阳性细胞数比对照组明显增加。细胞平均面积增大。结论后脚掌慢性炎症痛可以引起大鼠对伤害性热刺激的痛觉过敏，并导致脊髓背根神经节（L4—6）神经元qbP2X3受体阳性细胞数目增加，表明P2X3在DRG的中小神经元的改变可能对松节油引起脚掌炎症痛时热痛觉过敏的形成与维持起重要作用。

CHRONIC INFLAMMATORY PAIN INDUCES THE ALTERATION OF P2X3 RECEPTOR EXPRESSION IN DORSAL ROOT GANGLIA

Objective To investigate the role of dorsal root ganglia（DRG） P2X3 receptors in chermal hyperalgesia of rat plantar chronic inflammatory pain. Methods The model of right plantar chronic inflammation pain was established by hypodermic injection of turpentine oil（TO） and paraffin（50% each） 0. 1ml according to the method of behavior research. The pain threshold of planta was measured once a day within 15days using thermal measurement apparatus of pain. The distribution change of the P2X3 receptor positive cell types in dorsal root ganglia （L4-6） neurons on thet inflammation side was observed at the second day and the seventh day by using immunohistochemical technology and compared with that of normal rats.Results 1） The changes reached the lowest value at day 2 and recovered to the normal level at day 14 after inflammation.2）P2X3 appeaed mainly in small and medium neurons of DRG in normal rats.The average size and number of DRG small and medium P2X3 receptor positive cells grew obviously after inflammation.Conclusion The chronic inflammatory pain of the planta can cause pain hypersusceptibility to nociceptive heat stimulation, and lead to the increase of P2X3 receptor positive cells in dorsal root ganglia（L4-6）,which indicate that the change of P2X3 in DRG small and medium neurons probably plays an important role in the formation and maintenance of thermal hyperalgesia heat stimulation caused by plantar inflammatory pain through turpentine injection.