蛋白激酶A和蛋白激酶C对大鼠背根神经节神经元P2X_3受体介导的内向电流的调节作用

Regulatory effect of protein kinase A and protein kinase C on P2X_3 - mediated inward current in rat dorsal root ganglion neurons

目的探讨蛋白激酶A(PKA)和蛋白激酶C(PKC)对分离培养的背根神经节(DRG)神经元ATP受体P2X3功能的调节作用。方法分离培养大鼠DRG神经元,给予外源性ATP诱导出瞬时型内向电流,通过全细胞膜片钳记录的方法观察P2X3和P2X2/3受体特异性阻断剂TNP-ATP对这一电流的影响,在此基础上观察PKA和PKC激动剂对ATP诱导的瞬时型内向电流的调节作用。结果在分离培养的DRG神经元上,ATP诱导的瞬时型电流可以被TNP-ATP抑制,其抑制效应呈剂量依赖性,半数有效剂量(IC50)为(21.7±7.6)nmol/L。PKA激动剂forskolin(1μmol/L)和PKC激动剂PMA(1μmol/L)均可以快速、可逆地抑制ATP诱导的瞬时型电流。结论在大鼠分离培养的DRG神经元,PKA和PKC可能通过磷酸化调节抑制P2X3受体的功能,从而抑制ATP诱导的瞬时型内向电流,提示蛋白激酶对P2X3受体的调节作用可能参与痛觉的形成。

Objective To investigate the regulatory effect of protein kinase A（PKA） and protein kinase C（PKC） on the function of ATP receptor P2X3 in cultured dorsal root ganglion（DRG） neurons.Methods Rat DRG neurons were collected,cultured and subjected to exogenous ATP treatment to induce transient inward current.Whole-cell patch clamp recording was employed to observe the effect of TNP-ATP（P2X3 and P2X2/3 receptor antagonist） on the induced current.Meanwhile,the regulatory effects of PKA and PKC agonist on ATP-induced transient inward current were also observed.Results TNP-ATP inhibited ATP-induced transient current in cultured DRG neurons in a dose-dependent manner,with the IC50 value being（21.7 ± 7.6） nmol/L.PKA agonist forskolin（1 μmol/L） and PKC agonist PMA（1 μmol/L） inhibited ATP-induced transient current rapidly and reversibly.Conclusion PKA and PKC can inhibit ATP-induced transient inward current in cultured DRG neurons,probably through inhibiting the function of P2X3 receptors.It indicates that P2X3 receptor regulation by protein kinases may participate in the development of pain.