神经元Kv7电压门控钾通道产生M电流并调节神经元兴奋性。这里,我们报道硫酸脱氢表雄酮(DHEAS)是一种内源性Kv7通道调节剂,可减弱Gq偶联受体诱导的M电流抑制.DHEAS降低了毒蕈碱激动剂诱导的Kv7电流对大鼠交感神经节神经元中Kv7.1,Kv7.2,Kv7.4或Kv7.5同源电流和内源性M电流的抑制。然而,DHEAS本身没有改变这些Kv7同源通道的电压依赖性或m1受体诱导的磷脂酶C或蛋白激酶C的激活。DHEAS处理的Kv7.2同源电流对磷脂酰肌醇4,5-二磷酸(PIP2)的消耗具有抗性由电压激活的磷酸酶,Ci-VSP或eVSP。我们的计算模型预测了Kv7亚基的细胞质结构域中DHEAS的新结合位点。预测的关键组氨酸在大鼠Kv7.2亚基中单点突变为半胱氨酸,rKv7.2(H558C),导致DHEAS对毒蕈碱Kv7电流抑制的作用丧失。此外,在福尔马林爪试验中,在两性小鼠体内施用DHEAS可减少晚期疼痛反应。然而,它对福尔马林爪试验的早期反应或热板试验的反应没有影响。联合使用选择性Kv7抑制剂,XE991和DHEAS在福尔马林爪试验中消除了DHEAS在晚期反应中的镇痛作用。总的来说,这些结果表明,DHEAS通过稳定PIP2-Kv7亚基相互作用减弱M-电流抑制,并可减轻炎性疼痛.意义StatementM-通过刺激Gq偶联受体诱导的电流抑制是Kv7电流调制的一种形式,可以可逆地增加神经元兴奋性。这项研究表明,DHEAS,一种内源性类固醇激素,是一种新型的Kv7通道调制器,可以在不影响基础Kv7通道动力学的情况下衰减M电流抑制。体内施用DHEAS减轻了啮齿动物的炎性疼痛。这些结果表明,小分子可以动态调节M电流抑制的程度。因此,这种新形式的Kv7通道调节具有作为致敏神经活动如炎性疼痛的治疗靶点的潜力.
Neuronal Kv7 voltage-gated potassium channels generate the M-current and regulate neuronal excitability. Here, we report that dehydroepiandrosterone sulfate (DHEAS) is an endogenous Kv7 channel modulator that attenuates Gq-coupled receptor-induced M-current suppression. DHEAS reduced muscarinic agonist-induced Kv7-current suppression of Kv7.1, Kv7.2, Kv7.4, or Kv7.5 homomeric currents and endogenous M-currents in rat sympathetic ganglion neurons. However, DHEAS per se did not alter the voltage dependence of these Kv7 homomeric channels or the m1 receptor-induced activation of phospholipase C or protein kinase C. DHEAS-treated Kv7.2 homomeric currents became resistant to depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) induced by voltage-activated phosphatase, Ci-VSP or eVSP. Our computational models predicted a novel binding site for DHEAS in the cytoplasmic domain of Kv7 subunits. A single-point mutation of the predicted key histidine into cysteine in the rat Kv7.2 subunit, rKv7.2(H558C), resulted in a loss of effects of DHEAS on muscarinic Kv7 current suppression. Furthermore, in vivo administration of DHEAS in mice of both sexes reduced late phase pain responses in the formalin paw test. However, it did not have effects on early phase responses in the formalin paw test or responses in the hot plate test. Coadministration of a selective Kv7 inhibitor, XE991, and DHEAS eliminated analgesic effects of DHEAS in late phase responses in the formalin paw test. Collectively, these results suggest that DHEAS attenuates M-current suppression by stabilizing PIP2-Kv7 subunit interaction and can mitigate inflammatory pain.SIGNIFICANCE STATEMENT M-current suppression induced by stimulation of Gq-coupled receptors is a form of Kv7 current modulation that can reversibly increase neuronal excitability. This study demonstrates that DHEAS, an endogenous steroid hormone, is a novel Kv7 channel modulator that can attenuate M-current suppression without affecting basal Kv7 channel kinetics. Administration of DHEAS in vivo alleviated inflammatory pain in rodents. These results suggest that the degree of M-current suppression can be dynamically regulated by small molecules. Therefore, this novel form of Kv7 channel regulation holds promising potential as a therapeutic target for sensitized nervous activities, such as inflammatory pain.