Wickenden A D, Krajewski J L, London B, Wagoner P K, Wilson W A, Clark S, Roeloffs R, McNaughton-Smith G, Rigdon G C
Icagen, Inc., 4222 Emperor Blvd., Durham, NC 27703, USA.
Mol Pharmacol. 2008 Mar;73(3):977-86. doi: 10.1124/mol.107.043216. Epub 2007 Dec 18.
KCNQ2 (Kv7.2) and KCNQ3 (Kv7.3) are voltage-gated K(+) channel subunits that underlie the neuronal M current. In humans, mutations in these genes lead to a rare form of neonatal epilepsy (Biervert et al., 1998; Singh et al., 1998), suggesting that KCNQ2/Q3 channels may be attractive targets for novel antiepileptic drugs. In the present study, we have identified the compound N-(6-chloro-pyridin-3-yl)-3,4-difluoro-benzamide (ICA-27243) as a selective activator of the neuronal M current and KCNQ2/Q3 channels. In SH-SY5Y human neuroblastoma cells, ICA-27243 produced membrane potential hyperpolarization that could be prevented by coadministration with the M-current inhibitors 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE-991) and linopirdine. ICA-27243 enhanced both (86)Rb(+) efflux (EC(50) = 0.2 microM) and whole-cell currents in Chinese hamster ovary cells stably expressing heteromultimeric KCNQ2/Q3 channels (EC(50) = 0.4 microM). Activation of KCNQ2/Q3 channels was associated with a hyperpolarizing shift of the voltage dependence of channel activation (V((1/2)) shift of -19 mV at 10 microM). In contrast, ICA-27243 was less effective at activating KCNQ4 and KCNQ3/Q5 and was selective over a wide range of neurotransmitter receptors and ion channels such as voltage-dependent sodium channels and GABA-gated chloride channels. ICA-27243 (1-10 microM) was found to reversibly suppress seizure-like activity in an ex vivo hippocampal slice model of epilepsy and demonstrated in vivo anticonvulsant activity (ED(50) = 8.4 mg/kg) in the mouse maximal electroshock epilepsy model. In conclusion, ICA-27243 represents the first member of a novel chemical class of selective KCNQ2/Q3 activators with anticonvulsant-like activity in experimental models of epilepsy.
KCNQ2（Kv7.2）和KCNQ3（Kv7.3）是构成神经元M电流基础的电压门控钾离子通道亚基。在人类中，这些基因的突变会导致一种罕见的新生儿癫痫（Biervert等人，1998年；Singh等人，1998年），这表明KCNQ2/Q3通道可能是新型抗癫痫药物的有吸引力的靶点。在本研究中，我们已确定化合物N-（6-氯吡啶-3-基）-3,4-二氟苯甲酰胺（ICA-27243）为神经元M电流和KCNQ2/Q3通道的选择性激活剂。在SH-SY5Y人神经母细胞瘤细胞中，ICA-27243可使膜电位超极化，与M电流抑制剂10,10-双（4-吡啶基甲基）-9（10H）-蒽酮二盐酸盐（XE-991）和利诺吡啶共同给药可阻止这种超极化。ICA-27243可增强稳定表达异源多聚体KCNQ2/Q3通道的中国仓鼠卵巢细胞中的（86）Rb（+）外流（EC50 = 0.2微摩尔）和全细胞电流（EC50 = 0.4微摩尔）。KCNQ2/Q3通道的激活与通道激活电压依赖性的超极化移位相关（在10微摩尔时V（1/2）移位为-19毫伏）。相比之下，ICA-27243在激活KCNQ4和KCNQ3/Q5方面效果较差，并且在多种神经递质受体和离子通道（如电压依赖性钠通道和GABA门控氯通道）中具有选择性。发现ICA-27243（1-10微摩尔）可在癫痫的离体海马切片模型中可逆地抑制癫痫样活动，并在小鼠最大电休克癫痫模型中表现出体内抗惊厥活性（ED50 = 8.4毫克/千克）。总之，ICA-27243代表了一类新型化学选择性KCNQ2/Q3激活剂中的首个成员，在癫痫实验模型中具有类似抗惊厥的活性。
