Promotive effect of neurosteroids on memory- and emotion-related neuronal communication in the hippocampus

神经类固醇对海马记忆和情绪相关神经元通讯的促进作用

• 批准号: 11480187
• 负责人: KAWATO Suguru
• 金额: $ 9.92万
• 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 (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11480187/
• 关键词: hippocampus; neurosteroid; learning and memory; cytochrome P450; estradiol; stress; LTP; calcium; 神経ステロイド; チトクロムP450c17; DHEA; チトクロムP450scc; 硫酸プレグネノロン; NMDA

Neurosteroids, produced de novo in the brain, regulate learning and memory processes by acutely modulating the ion conductivity of neurotransmitter receptors in hippocampal neurons. The pathway of neurosteroidogenesis and the regulation mode of neuronal signal transmission have not been well-elucidated. In the present study, we have discovered that a neurosteroidogenic system, composed of cytochrome P450scc, hydroxysteroid sulfotransferase, steroidogenic acute regulatory protein (StAR), 3beta-hydroxysteroid dehydrogenase, P450c17 and P450arom, localizes in pyramidal neurons and granule neurons in the rat hippocampus. This indicates that the main source of neurosteroids in the hippocampus is not glial cells, as has been believed, but neurons. Furthermore, we have found, with HPLC analysis and radioimmunoassay, that cholesterol is actively metabolized to 17beta-estradiol (E2) through precursor steroids, pregnenolone, dehydroepiandrosterone (DHEA) and androsterone. We have also found that … More the rate of neurosteroidogenesis was regulated through mitochondrial StAR processing, which was acutely induced by Ca^<2+> influx via NMDA receptors. P450c17 enzyme and its activity (DHEA synthesis) were demonstrated for the first time in the mammalian brain, by which we can now regard downstream steroids, such as E2 and teststerone, as 'true' neurosteroids.We also examined the acute effect of neurosteroids on the signal transmission of hippocampal neurons. Pregnenolone sulfate (500 nM) was observed to potentiate Ca^<2+> influx via NMDA receptors very acutely (within 1 sec), which resulted in the reduction in the strength of tetanus stimulation required to induce LTP (from 100 Hz, 1 sec to 30 Hz, 0.5 sec) in hippocampal slices prepared from 4-week-old male Wistar rats. Nitric oxide production in hippocampal neurons was also acutely promoted by the application with pregnenolone sulfate. A short time treatment with E2 (1-100 nM, 20 min) suppressed LTP formation, in dose-dependent manner, in hippocampal slices obtained from 4-week-old male Wistar rats and stimulated with tetanus stimulation (100 Hz, 1 sec). On the other hand, the same E2 treatment potentiated LTP in hippocampal slices prepared from 10-week-old male rats. These results suggest that the mode of E2 action on neuronal signal transmission varies depending on the age of animals from which hippocampal slices were obtained. Corticosterone, a most potent stress steroid, suppressed LTP induction and Ca^<2+> influx via NMDA receptors in hippocampal slices. This result might give the cell physiological basis for PTSD induced by the acute and strong stress. Less

神经甾体，在大脑中重新产生，通过急性调节海马神经元中神经递质受体的离子电导率来调节学习和记忆过程。神经甾体生成的途径和神经元信号传递的调控模式尚未完全阐明。在本研究中，我们发现了一个神经甾体生成系统，包括细胞色素P450 SCC，羟类固醇磺基转移酶，甾体生成急性调节蛋白（星星），3 β-羟类固醇脱氢酶，P450 c17和P450 arom，定位于锥体神经元和颗粒神经元在大鼠海马。这表明海马体中神经甾体的主要来源不是人们认为的神经胶质细胞，而是神经元。此外，我们发现，与HPLC分析和放射免疫测定，胆固醇是积极代谢为17 β-雌二醇（E2）通过前体类固醇，双烯醇酮，脱氢表雄酮（DHEA）和雄酮。我们还发现 ...更多信息 神经类固醇生成速率通过线粒体StAR加工来调节，线粒体StAR加工是由Ca^<2+>通过NMDA受体内流急性诱导的。P450 c17酶及其活性（脱氢表雄酮合成）在哺乳动物脑中首次得到证实，我们现在可以把下游的甾体如E2和teststerone看作“真正的”神经甾体，我们还研究了神经甾体对海马神经元信号传递的急性效应。研究发现，硫酸孕烯醇酮（500 nM）可以非常迅速地（在1秒内）增强通过NMDA受体的Ca^2+内流，这导致在4周龄雄性Wistar大鼠海马切片中诱导LTP所需的破伤风刺激强度降低（从100 Hz，1秒降低到30 Hz，0.5秒）。海马神经元中一氧化氮的产生也被硫酸双烯醇酮急性促进。E2（1-100 nM，20 min）短时间处理抑制LTP形成，在剂量依赖性的方式，在海马切片从4周龄雄性Wistar大鼠和破伤风刺激（100 Hz，1 sec）刺激。另一方面，同样的E2治疗增强了10周龄雄性大鼠海马脑片的LTP。这些结果表明，E2对神经元信号传递的作用模式根据获得海马切片的动物的年龄而变化。皮质酮是一种最有效的应激类固醇，它通过NMDA受体抑制海马脑片LTP的诱导和Ca^2+内流。这一结果可能为急性强应激诱发PTSD提供了细胞生理学依据。少

项目成果

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Ichikawa,T.：“脑星形胶质细胞中含有低密度脂蛋白的内体运输的数字荧光成像”Biochem.Biophys.Res.Commun..（出版中）。

Kawato,S.: "Localization and activities of neurosteroidogenic systems in the hippocampal neurons. in Molocular Steroidogenesis"Universal Academy Press. 4 (2000)

Kawato，S.：“海马神经元中神经类固醇生成系统的定位和活动。在分子类固醇生成中”环球学院出版社。

Mukai, H.: "Effects of neurosteroids on Ca^<2+> signaling mediated by recombinant NMDA receptor expressed in CHO cells"Neurosci.Lett.. 282. 93-96 (2000)

Mukai，H.：“神经类固醇对CHO细胞中表达的重组NMDA受体介导的Ca ^ 2 信号传导的影响”Neurosci.Lett.. 282. 93-96 (2000)

Kawato,S.: "Neurosteroids are 4th generation neuromessengers : cell biophysics analysis of steroid signal transduction."Adv.Biophys.. 37(in press). (2001)

Kawato,S.：“神经类固醇是第四代神经信使：类固醇信号转导的细胞生物物理学分析。”Adv.Biophys.. 37（印刷中）。

Kimoto T, Tsurugizawa T, Ohta Y, Makino J, Tamura H, Hojo Y, Enami, T, Kawato S.: "Cytochrome P450-dependent neurosteroid synthesis in the rat brain hippocampal neurons"Excerpta Medica International Congress Series. (in press).

Kimoto T、Tsrugizawa T、Ohta Y、Makino J、Tamura H、Hojo Y、Enami、T、Kawato S.：“大鼠脑海马神经元中细胞色素 P450 依赖性神经类固醇合成”医学摘录国际大会系列。