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

• 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
• 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

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）：小传导钙活化的钾通道由KCA2.1-2.3（= SK1-3）基因编码，并以神经元中的丙氨酸敏感培养基（MAHP）为基础而闻名。根据神经元的类型，KCA2通道的功能因确定瞬时射击速率而异，而在设置强调射击频率上，到调节爆发发射和潜在的儿茶酚胺释放。因此，KCA通道的药理调节提供了显着影响神经元兴奋性的机会。尽管KCA2通道阻滞剂（如蜜蜂毒Apamin）增加了啮齿动物的发射速率并诱导癫痫发作，但KCA2通道激活剂会减慢神经元的射击，因此已提出用于治疗中枢神经系统疾病的特征，这些疾病的特征是癫痫，共济失调，共济失调和神经病力疼痛。但是，目前，这种引人注目的治疗假设仍然未经测试，因为现有的KCA2通道激活剂（例如EBIO（EC50300μM）或NS309）都不适合体内使用。 我们的实验室使用神经保护药物riluzole作为合成模板，最近设计了SKA-31（EC50 2 UM），这是第一个KCA2通道激活剂，该激活剂足够有效，可以在体内使用，并与NIH抗惊厥药筛查程序（ASP）合作证明，其化合物和几个化合物和几种衍生物有效。不幸的是，SKA-31还激活了在血管内皮上表达的KCA3.1通道，从而降低了小鼠的血压。使用经典药物化学和自动化和手动电生理学的结合，我们打算进一步探索SKA 31和EBIO周围的结构活动关系，以提高KCA2对KCA3.1的选择性，以及效力和大脑渗透。然后，将评估最佳新的KCA2激活剂对克隆离子通道的选择性，并使用海马切片对天然KCA2通道的活性进行特征。选择性激活克隆和天然KCA2通道的化合物将进一步评估使用HPLC/MS的大鼠的药代动力学特性和脑穿透。同时，我们将向ASP提交选定的化合物，在该ASP中，我们将在急性癫痫发作模型中测试这些化合物。然后，有前景的化合物将在杏仁核点燃的小鼠和大鼠具有海藻酸盐诱导的癫痫病的大鼠中进行测试，这是两个模型，这些模型更具代表人类难治性癫痫。大脑渗透剂和潜在的亚型选择性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型药理学靶标，并将进一步为科学界提供工具化合物，以研究KCA2通道在共济失调，神经性疼痛和认知中的作用。 公共卫生相关性：项目叙事KCA2钾通道在确定神经元兴奋性方面起着重要作用。因此，这些通道的激活因素被认为是用于治疗具有神经元过度兴奋的疾病（例如癫痫和共济失调）的新疗法。在这笔赠款的帮助下，我们将尝试设计一个具有足够有效和选择性的KCA2通道激活剂，以用作科学工具化合物，甚至可以将其开发为药物。