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論文
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Sugiyama, Chie ; Nakamichi, Noritaka ; Ogura, Masato ; Honda, Eriko ; Maeda, Sayaka ; Taniura, Hideo ; Yoneda, Yukio
概要:
金沢大学大学院自然科学研究科分子作用学<br />Activation of ionotropic glutamate (Glu) receptors, such as N-methyl-d-aspartate receptors, is
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shown to modulate the gene transcription mediated by the transcription factor activator protein-1 (AP1) composed of Fos and Jun family proteins in the brain, while little attention has been paid to the modulation of AP1 expression by metabotropic Glu receptors (mGluRs). In cultured rat cortical neurons, where constitutive expression was seen with all groups I, II and III mGluR subtypes, a significant and selective increase was seen in the DNA binding activity of AP1 120 min after the brief exposure to the group II mGluR agonist (2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG-IV) for 5 min. In cultured rat cortical astrocytes, by contrast, a significant increase was induced by a group I mGluR agonist, but not by either a group II or III mGluR agonist. The increase by DCG-IV was significantly prevented by a group II mGluR antagonist as well as by either an intracellular Ca2+ chelator or a voltage-sensitive Ca2+ channel blocker, but not by an intracellular Ca2+ store inhibitor. Moreover, DCG-IV significantly prevented the increase of cAMP formation by forskolin in cultured neurons. Western blot analysis revealed differential expression profiles of Fos family members in neurons briefly exposed to DCG-IV and NMDA. Prior or simultaneous exposure to DCG-IV led to significant protection against neuronal cell death by NMDA. These results suggest that activation of the group II mGluR subtype would modulate the gene expression mediated by AP1 through increased intracellular Ca2+ levels in cultured rat cortical neurons. © 2007.
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論文
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米田, 幸雄 ; Yoneda, Yukio
概要:
成熟脳においても脳室下帯や海馬歯状回においては、発達脳の場合と同様に神経系前駆細胞が存在して、ニューロン新生が行われることが明らかとなっている。したがって、成熟マウス海馬歯状回に発現する神経系前駆細胞のストレス負荷に伴う影響について、新規D
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NA合成の指標となる、5-bromo-2-deoxyuridine (BrdU)の取り込み活性により検討を行った。その目的で、成熟Std-ddY系雄性マウスを金属製のストレスケージにより拘束して、25℃の水浴中に鎖骨下まで各時間浸してストレス負荷を行った。胃粘膜に対するストレス負荷の影響は検鏡により確認した。BrdU(50mg/kg)は、ストレス3時間負荷直後と12時間後に合計2回腹腔内投与した。最初のBrdU投与から24時間後に、4%パラホルムアルデヒド液を用いて動物の灌流固定を行ったのち、厚さ50μm凍結海馬冠状切片を作成し、BrdU抗体を用いて免疫組織化学法を行った。両側の海馬におけるsubgranular layerおよびhilus内のBrdU陽性細胞数、クラスター形成細胞数、およびクラスター数をそれぞれ計測して定量化した。その結果、動物へのストレス負荷時間の長さに依存して、激しい出血性胃粘膜傷害が認められた。成熟マウス脳海馬歯状回では、顆粒細胞層および側脳室下帯においてそれぞれBrdU陽性細胞が検出されたが、海馬歯状回において観察された陽性細胞数はBrdU投与後時間経過に伴って減少した。動物にストレスを3時間負荷すると、海馬歯状回で検出されたBrdU陽性細胞数、クラスター形成細胞数、およびクラスター数は、いずれも対照群に比べて有意に減少した。以上の結果から、成熟動物へのストレス負荷は、海馬歯状回に発現する神経系前駆細胞の増殖能を抑制する可能性が示唆される。<br />The present study deals with evaluation of molecular mechanisms associated with crisis of the posttraumatic disorder often seen with subjects in severe stressful situations. Patients would recall the stressful experience they had before months and years later. This could involve long-term consolidation of transient signals through modulation of de novo synthesis of particular target proteins at the level of gene transcription in the brain. Transcription factors are nuclear proteins with high affinity for a particular core nucleotide sequence to modulate the activity of RNA polymerase II that is responsible for the formation of mRNA from genomic DNA in the nucleus. Animals were subjected to cold and immobilization stress for different periods, followed by dissection of discrete central and peripheral structures and subsequent preparation of nuclear extracts for determination of DNA binding activity of different transcription factors. A marked increase was seen in DNA binding activities of activator protein-1(AP1) and cyclic AMP responsive element binding protein (CREB) in the rat hypothalamus, pituitary and adrenal glands, but not in the cerebral neocortex, hippocampus and striatum. By contrast, cold and immobilization stress induced a significant decrease in the number of clusters formed by cells immunoreactive to 5-bromo-deoxyuridine(BrdU) in the granular layer of the dentate gyrus in mouse hippocampus. These results suggest that severe stressful situation would lead to attenuation of adult neurogenesis through modulation of gene expression by transcription factors in the brain. Search for the target genes is undoubtedly of great importance for the therapy and treatment of posttraumatic disorder in human beings.<br />研究課題/領域番号:13470487, 研究期間(年度):2001-2003<br />出典：「心的外傷後ストレス障害(トラウマ)発症の分子機構解明に関する研究」研究成果報告書 課題番号13470487 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
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