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Studies on substances of microbial origin which protect central nervous system

保护中枢神经系统的微生物来源物质的研究

基本信息

批准号：
10660104
负责人：
SHIN-YA Kazuo
金额：
$ 2.18万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In the course of our screening program for AMPA/kainate antagonists to treat brain ischemia injury known as stroke, we isolated a potent AMPA anatagonist designated kaitocephalin from a fungi identified to Eupenicillium shearii. This compound effectively protected rat hippocampal neurons from AMPA and kainate toxicity without showing cytotoxicity. Since the stereochemistry plays a significant role in the biological activities on glutamate receptor, we established the absolute stereochemistry of kaitocephalin as 2S3S4R7R9S by analyzing the NMR spectra such as NOEs applying to the chemically modified compounds.In the receptor binding assay for glutamate agonists, kaitocephalin showed potent binding activity to the agonist binding site of NMDA receptor. It also exhibited binding affinities AMPA receptor but showed slight binding activity on kainate receptor. In this way it has a high affinity to NMDA receptor, we investigated the protective effect of kaitocephalin against NMDA toxicity in … More rat hippocampal neurons. It effectively protected rat hippocampal neurons from neuronal damage induced by NMDA. To reveal the mode of action, we next studied the inhibitory effects of kaitocephalin on CaィイD12+ィエD1 influx induced by glutamate agonists. Kaitocephalin blocked CaィイD12+ィエD1 influx induced by AMPA but not by kainate in rat hippocampal neurons. This result is coincident to affinity binding experiments, but quite different from the hypothesis of CaィイD12+ィエD1 induced neurotoxicity. So that we employed rat hippocampal organotypic culture system using rat hippocampal slices in which the selective response to the different glutamate agonists could be observed. Kaitocephalin protected CA1 and CA3 regions from NMDA, AMPA and kainate. Kaitocephalin blocked CaィイD12+ィエD1 influx in CA1 and CA3 region elicited by NMDA and AMPA, respectively. To the contrary, kaitocephalin failed to block CaィイD12+ィエD1 influx mediated through kainate receptor. These results proved that CaィイD12+ィエD1 influx induced by glutamate agonists did not always attribute neuronal cell death. It is a quite important disovery in the central nervous physiology and also imply the novel hypothesis to the mechanism of neuronal cell death. Less

在我们筛选AMPA/kainate拮抗剂治疗脑缺血损伤（即中风）的过程中，我们从一种真菌中分离出一种有效的AMPA拮抗剂，命名为kaitocephalin。该化合物能有效保护大鼠海马神经元免受AMPA和海盐酸盐的毒性，而不显示细胞毒性。由于立体化学在谷氨酸受体的生物活性中起着重要的作用，我们通过分析化学修饰后的化合物的核磁共振谱（NOEs），确定了凯头脑苷的绝对立体化学为2S3S4R7R9S。在谷氨酸受体激动剂的受体结合实验中，kaiitocephalin对NMDA受体激动剂结合位点显示出强大的结合活性。对AMPA受体也表现出亲和力，但对盐酸盐受体的结合活性较弱。通过对NMDA受体的高亲和性，研究了凯头啡对NMDA毒性的保护作用。它能有效地保护大鼠海马神经元免受NMDA诱导的神经元损伤。为了揭示作用模式，我们进一步研究了凯头啡素对谷氨酸激动剂诱导的Ca γ γ - D12+ γ - D1内流的抑制作用。kaiitocephalin阻断AMPA诱导的大鼠海马神经元Ca γ γ γ - D12+ γ - D1内流，而非kainate诱导的。这一结果与亲和结合实验结果一致，但与Ca γ γ - D12+ γ - D1诱导神经毒性的假设有较大差异。因此，我们采用大鼠海马器官型培养系统，利用大鼠海马切片，观察对不同谷氨酸激动剂的选择性反应。Kaitocephalin保护CA1和CA3区域免受NMDA、AMPA和kainate的伤害。kaiitocephalin分别阻断NMDA和AMPA诱导的CA1和CA3区Ca γ γ - D12+ γ - D1内流。相反，kaiitocephalin未能阻断通过盐酸盐受体介导的Ca γ γ γ - D12+ γ - D1内流。这些结果证明谷氨酸激动剂诱导的Ca γ γ - D12+ γ - D1内流并不总是导致神经元细胞死亡。这是中枢神经生理学的一项重要发现，也为神经元细胞死亡机制提供了新的假说。少