Establishment of trigeminal neuralgia model and role of ATP receptor for neuropathic pain

ATP受体在神经性疼痛的发生过程中起着重要作用。此外，研究发现一种主要的抑制性神经递质γ-氨基丁酸（GABA）通过ATP受体的激活而作为兴奋性神经递质发挥作用。正常神经元胞内Cl^-浓度小于10 mM，脑外Cl^-浓度约为120-130mM。在这些条件下，GABA引起Cl^-通过GABA型通道向内流动。而在神经发育和周围神经损伤阶段，当细胞内Cl^-浓度升高时，GABA引起Cl^-向外流动。因此，GABA的释放导致神经元兴奋。这种GABA功能的改变在神经性疼痛模型中也存在。因此，在这一时期，利用电生理方法和酵母双杂交系统对氯离子转运体的功能进行了研究。酵母双杂交系统显示神经元特异性K^+- cl ^-共转运蛋白KCC2与脑型肌酸激酶相互作用。此外，利用稳定表达KCC2的HEK293细胞，脑型肌酸激酶激活KCC2，导致细胞内Cl^-升高。

ATP receptors play an important role of establishment of neuropathic pain. Moreove, it has been found that a major inhibitory neurotransmitter, γ-aminobutyric acid (GABA) functions as an excitatory neurotransmitter through ATP receptor activation. Intracellular Cl^- concentration of normal neurons is less than 10 mM, and external Cl concentration in the brain is around 120-130mM. Under these conditions, GABA causes inward flux of Cl^- through GABA typeA channels. In contrast, when intracellular Cl^- concentration increases during development stage of neuros and peripheral nerve injury, GABA cause outward flux of Cl^-. Consequently, GABA relase resulted in neuronal excitation. This change of GABA function is also found in neuropathic pain model. Thus, functions of cloride transporters were investigated, using electorphysilogical approach and yeast two-hybrid system in this period.The yeast two-hybrid system revealed that neuron-specific K^+-Cl^- cotransporter, KCC2, interacted with brain-type creatine kinase. In addition, using HEK293 cells stablly expressed KCC2, brain-type creatine kinase activated KCC2,resulting in an increase of intracellular Cl^-.