Optimization of KCa2 Channel Activators as Neuroscience Tools and Potential Drugs

KCa2 通道激活剂作为神经科学工具和潜在药物的优化

基本信息

批准号：
8191433
负责人：
HEIKE WULFF
金额：
$ 21.96万
依托单位：
UNIVERSITY OF CALIFORNIA AT DAVIS
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-08-01 至 2013-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8191433
关键词：
Acute Adverse effects Affect Amines Amygdaloid structure Anticonvulsants Antiepileptic Agents Apamin Ataxia Bee Venoms Benzimidazoles Blood Pressure Brain Calcium California Catecholamines Central Nervous System Diseases Cognition Collaborations Communities Drug Kinetics Electroconvulsive Shock Electrophysiology (science)Epilepsy Evaluation Exhibits Frequencies Genes Grant Half-Life High Pressure Liquid Chromatography Hippocampus (Brain)Hour Human Ion Channel Kindling (Neurology)Laboratories Learning Legal patent Libraries Manuals Memory Modeling Molecular Target Mus Neurologic Neurons Neuroprotective Agents Neurosciences Pain Penetration Pentylenetetrazole Performance Pharmaceutical Chemistry Pharmaceutical Preparations Pharmacology Pilocarpine Plasma Potassium Property Quantitative Evaluations Rattus Refractory Riluzole Rodent Role Screening procedure Seizures Sequence Homology Slice Status Epilepticus Structure-Activity Relationship Test Result Testing Therapeutic Toxic effect Transgenic Mice United States National Institutes of Health Universities Vascular Endothelium base benzimidazole benzothiazole calcium-activated potassium channel small-conductance channel blockers design improved in vivo kainate memory process neuronal excitability neurotoxicity novel painful neuropathy patch clamp pharmacophore prevent programs small molecule therapeutic target tool

项目摘要

DESCRIPTION (provided by applicant): Small-conductance calcium activated potassium channels are encoded by the KCa2.1-2.3 (= SK1-3) genes and are best known for underlying the apamin-sensitive medium afterhyperpolarization current (mAHP) in neurons. Depending on the type of neuron, the function of KCa2 channels varies from determining instantaneous firing rates, over setting tonic firing frequencies, to regulating burst firing and potentially catecholamine release. Pharmacological modulation of KCa channels therefore offers the opportunity to significantly affect neuronal excitability. While KCa2 channel blockers like the bee venom apamin increase firing rates and induce seizures in rodents, KCa2 channel activators slow down neuronal firing and have therefore been proposed for the treatment of CNS disorders that are characterized by hyperexcitability such as epilepsy, ataxia, and neuropathic pain. However, this compelling therapeutic hypothesis currently remains largely untested because none of the existing KCa2 channel activators such as EBIO (EC50 300 μM) or NS309 are suitable for in vivo use. Using the neuroprotective drug riluzole as a synthetic template, our laboratory recently designed SKA-31 (EC50 2 uM), the first KCa2 channel activator, which is potent enough to be used in vivo, and demonstrated in collaboration with the NIH Anticonvulsant Screening Program (ASP) that the compound and several of its derivatives are effective anticonvulsants. Unfortunately, SKA-31 also activates KCa3.1 channels, which are expressed on vascular endothelium, and thus reduces blood pressure in mice. Using a combination of classical medicinal chemistry and automated and manual electrophysiology we intend to further explore the structure activity relationship around SKA 31 and EBIO in order to improve selectivity for KCa2 over KCa3.1 as well as potency and brain penetration. The best new KCa2 activators will then be evaluated for selectivity over a panel of cloned ion channels and characterized for activity on native KCa2 channels using hippocampal slices. Compounds selectively activating cloned and native KCa2 channels will further be evaluated for pharmacokinetic properties and brain penetration in rats using HPLC/MS. In parallel, we will submit selected compounds to the ASP, where the compounds will we tested in acute seizure models. Promising compounds will then be tested in amygdala kindled mice and rats with kainate-induced epilepsy, two models that are more representative of human refractory epilepsy. The design of brain penetrant and potentially subtype selective KCa2 channel activators would help to validate KCa2 channels as novel pharmacological targets for the treatment of epilepsy and would further provide the scientific community with tool compounds to study the role of KCa2 channels in ataxia, neuropathic pain and cognition. PUBLIC HEALTH RELEVANCE: Project Narrative KCa2 potassium channels play important roles in determining neuronal excitability. Activators of these channels have therefore been suggested as new therapeutics for the treatment of diseases that are characterized by neuronal hyperexcitability such as epilepsy and ataxia. With the help of this grant we will attempt to design a KCa2 channel activator that is potent and selective enough to be used as a scientific tool compound or even to be developed into a drug.

描述（由申请人提供）：小电导钙激活钾通道由 KCa2.1-2.3 (= SK1-3) 基因编码，最出名的是神经元中 apamin 敏感介质后超极化电流 (mAHP)。根据神经元的类型，KCa2 通道的功能各不相同，从确定瞬时放电率、设置强直放电频率到调节突发放电和潜在的儿茶酚胺释放。因此，KCa 通道的药理学调节提供了显着影响神经元兴奋性的机会。 KCa2 通道阻滞剂（如蜂毒阿帕明）会增加啮齿类动物的放电频率并诱发癫痫发作，而 KCa2 通道激活剂会减慢神经元放电，因此被提议用于治疗以过度兴奋为特征的中枢神经系统疾病，例如癫痫、共济失调和神经性疼痛。然而，这一令人信服的治疗假说目前在很大程度上仍未得到检验，因为现有的 KCa2 通道激活剂如 EBIO (EC50 300 μM) 或 NS309 都不适合体内使用。我们的实验室以神经保护药物利鲁唑为合成模板，最近设计了SKA-31（EC50 2 uM），这是第一个KCa2通道激活剂，其效力足以在体内使用，并与NIH抗惊厥筛选项目合作进行了演示（ ASP）表明该化合物及其几种衍生物是有效的抗惊厥药。不幸的是，SKA-31 还会激活表达于血管内皮的 KCa3.1 通道，从而降低小鼠血压。结合经典药物化学和自动和手动电生理学，我们打算进一步探索 SKA 31 和 EBIO 周围的结构活性关系，以提高 KCa2 相对于 KCa3.1 的选择性以及效力和脑渗透性。然后，将评估最好的新型 KCa2 激活剂对一组克隆离子通道的选择性，并使用海马切片表征其对天然 KCa2 通道的活性。将使用 HPLC/MS 进一步评估选择性激活克隆和天然 KCa2 通道的化合物的药代动力学特性和大鼠脑渗透性。与此同时，我们将向 ASP 提交选定的化合物，并在急性癫痫模型中测试这些化合物。然后将在杏仁核点燃的小鼠和红藻氨酸诱发癫痫的大鼠中测试有前景的化合物，这两种模型更能代表人类难治性癫痫。脑渗透剂和潜在亚型选择性 KCa2 通道激活剂的设计将有助于验证 KCa2 通道作为治疗癫痫的新药理学靶点，并将进一步为科学界提供工具化合物来研究 KCa2 通道在共济失调、神经性疼痛和认识。公共健康相关性：项目叙述 KCa2 钾通道在确定神经元兴奋性方面发挥着重要作用。因此，这些通道的激活剂被建议作为治疗以神经元过度兴奋为特征的疾病（例如癫痫和共济失调）的新疗法。在这笔资金的帮助下，我们将尝试设计一种 KCa2 通道激活剂，该激活剂具有足够的效力和选择性，足以用作科学工具化合物，甚至可以开发成药物。