Excitatory Amino Acid Release in Ischemia

缺血时的兴奋性氨基酸释放

• 批准号: 6898184
• 负责人: Harold K Kimelberg
• 金额: $ 41.25万
• 依托单位: ORDWAY RESEARCH INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6898184
• 关键词: astrocytes; brain disorder chemotherapy; calmodulin; caveolas; cerebral ischemia /hypoxia; chemoprevention; dosage; excitatory aminoacid; glutamate transporter; immunocytochemistry; ion transport; laboratory rat; membrane channels; membrane transport proteins; neuropharmacology; neuroprotectants; neurotransmitter transport; nonhuman therapy evaluation; stroke therapy; tamoxifen; tissue /cell culture

DESCRIPTION (Adapted from applicant's abstract): Our major hypothesis for the last funded period was that reversal of EAA transporters and activation of Volume-Regulated Anion Channels (YRACs) are major sources of EAAs in rat cerebral ischemia and that inhibition of these routes of release would be neuroprotective. In support of the first part of this hypothesis, we found that elevated extracellular [K+] induced EAA release due to both reversal of the EAA transporter and activation of VRACs in primary asfrocyte cultures. In vivo, microdialysis studies in a rat temporary global ischemia model established that application via a microdialysis probe of dihydrokainaxe, an inhibitor of the astrocyte-specific EAA transporter GLT-1, or DNDS an anion channel inhibitor, led to potent suppression of EAA levels during the ischemic episode. If applied together these compounds reduced EAA levels in ischemia by over 80 percent. To check whether inhibition of VRACs is neuroprotective, we chose, on the basis of its high blood-brain barrier permeability, the estrogen receptor antagonist/agonist tamoxifen (TAM) that is also an efficient inhibitor of VRACs in vitro. In the rat middle cerebral artery occlusion model (rMCAO), 5 mg/kg TAM reduced infarction volume by up to 80 percent if applied just before the 2 hour ischemic episode or 3 h after initiation of ischemia. We propose to continue these studies along two lines. One will be devoted to molecular identification of VRACs and intracellular signalling events involved in the volume-dependent release of EAAs in primary astrocyte cultures. Our hypotheses for this part of the project are that more than one VRAC is involved in volume-dependent amino acid release, one or more of these channels are incorporated in calveolae signaling complexes and calmodulin and tyrosine kinases are involved in their volume-dependent activation. The second line of the study will be to explore the molecular mechanisms of TAM neuroprotection and evaluation of its therapeutic window with different dosages and with different durations of reversible middle cerebral artery occlusion. Our hypothesis here is that TAM is highly neuroprotective in rMCAo because it has multiple protective effects. These include inhibition of VRACs, suppression of Ca24 about/calmodulin-dependent nitric oxide production, and/or antioxidant action. We also cannot exclude that some portion of the protection may also be mediated by brain estrogen receptors. This second part of the project will test all these possibilities in animal studies. Both aspects of the project will add new basic knowledge on VRACs, with the potential for understanding their functions in the brain. The second half of the project that deals with neuroprotection has direct potential clinical implications, as TAM is known to be well tolerated in humans being widely used for breast cancer treatment.

描述（改编自申请人的摘要）：我们的主要假设 上一个资助期是逆转EAA转运蛋白和激活 容量调节阴离子通道（YRAC）是大鼠EAA的主要来源 脑缺血，抑制这些释放途径将是 神经保护为了支持这一假设的第一部分，我们发现， 升高的细胞外[K+]诱导EAA释放，由于EAA的两种逆转 转运蛋白和VRAC的活化。在体内， 在大鼠暂时性全脑缺血模型中的微透析研究确定， 通过微透析探针的二氢海奈昔的应用， 星形胶质细胞特异性EAA转运蛋白GLT-1，或DNDS阴离子通道抑制剂， 导致缺血发作期间EAA水平的有效抑制。如果应用 这些化合物一起降低了缺血中超过80%的EAA水平。到 为了检查VRAC的抑制是否具有神经保护作用，我们选择，基于 其血脑屏障的高渗透性，雌激素受体 拮抗剂/激动剂他莫昔芬（TAM），也是VRAC的有效抑制剂 体外在大鼠大脑中动脉闭塞模型（rMCAO）中，5 mg/kg 如果在第2天之前应用TAM， 缺血发作后3小时或缺血开始后3小时。我们建议 继续这些研究沿着两条路线。其中一个将致力于分子 鉴定VRAC和细胞内信号传导事件参与 原代星形胶质细胞培养物中EAA的体积依赖性释放。我们的假设 项目的这一部分涉及多个VRAC 体积依赖性氨基酸释放，这些通道中的一个或多个是 整合在小窝信号复合物和钙调蛋白和酪氨酸 激酶参与其体积依赖性激活。第二行 本研究旨在探讨TAM神经保护作用的分子机制 并评估其不同剂量的治疗窗， 可逆性大脑中动脉闭塞的不同持续时间。我们 这里假设TAM在rMCAo中具有高度神经保护作用，因为它具有 多重保护作用。这些包括VRAC的抑制， Ca 24/钙调蛋白依赖性一氧化氮产生，和/或抗氧化剂 行动上我们也不能排除某些保护措施也可能 由脑雌激素受体介导。该项目的第二部分将测试 所有这些动物研究的可能性。 该项目的两个方面都将增加关于VRAC的新的基本知识， 了解它们在大脑中的功能。下半年 涉及神经保护项目具有直接的潜在临床意义 影响，因为已知TAM在人类中具有良好的耐受性， 用于乳腺癌治疗。

项目成果

Disruption of ionic and cell volume homeostasis in cerebral ischemia: The perfect storm.

• DOI: 10.1016/j.pathophys.2007.09.009
• 发表时间: 2007-12-01
• 期刊: Pathophysiology : the official journal of the International Society for Pathophysiology
• 作者: Mongin, Alexander A

Inhibition of ischemia-induced glutamate release in rat striatum by dihydrokinate and an anion channel blocker.

• DOI: 10.1161/01.str.30.2.433
• 发表时间: 1999-02
• 期刊: Stroke
• 影响因子: 8.3
• 作者: Y. Seki;P. Feustel;R. Keller;B. Tranmer;H. Kimelberg

Tamoxifen mediated estrogen receptor activation protects against early impairment of hippocampal neuron excitability in an oxygen/glucose deprivation brain slice ischemia model.

• DOI: 10.1016/j.brainres.2008.10.015
• 发表时间: 2009-01-09
• 期刊: Brain research
• 影响因子: 2.9
• 作者: Zhang H;Xie M;Schools GP;Feustel PF;Wang W;Lei T;Kimelberg HK;Zhou M
• 通讯作者: Zhou M

Volume regulated anion channel currents of rat hippocampal neurons and their contribution to oxygen-and-glucose deprivation induced neuronal death.

体积调节大鼠海马神经元的阴离子通道电流及其对氧和葡萄糖剥夺引起的神经元死亡的贡献。

• DOI: 10.1371/journal.pone.0016803
• 发表时间: 2011-02-11
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Zhang H;Cao HJ;Kimelberg HK;Zhou M
• 通讯作者: Zhou M

Tamoxifen as a powerful neuroprotectant in experimental stroke and implications for human stroke therapy.

他莫昔芬作为实验性中风的强大神经保护剂及其对人类中风治疗的影响。

• DOI: 10.2174/157488908784534603
• 发表时间: 2008
• 期刊: Recent patents on CNS drug discovery
• 作者: Kimelberg,HaroldK