Moleculare Mechanisms of Synapse Elimination and Stabilization in Developing Brain

大脑发育过程中突触消除和稳定的分子机制

• 批准号: 08458264
• 负责人: KANO Masanobu
• 金额: $ 5.57万
• 依托单位: The Institute of Physical and Chemical Research (RIKEN)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08458264/
• 关键词: mouse; cerebellum; Purkinje cell; climbing fiber synapse; patch clamp; postnatal development; multiple innervation; knockout mouse

(1) Postnatal development of cerebellar climbing fiber synaptic response :Electrophysiological investugation was performed to follow the developmental change of cerebellar climbing fiber (CF) to Purkinje cell (PC) synaptic responses in mice. Percentage of PCs innervated by multiple CFs decreased markedly during the first two postnatal weeks. Climbing fiber responses during the first postnatal week had slower rise times and exhibited greaterer extent of paired-pulse depression than those of mature animals. We have demonstrated in the rat that paired-pulse depression is mainly due to decreased transmitter release from CF presynaptic terminals.(2) Analyzes of mGluR1, Galphaq and PLCbeta4 delicient mice :The type 1 metabotropic glutamate receptor (mGluR1) is considered to activate in PCs protein kinase Cgamma (PKCgamma) through Gq type heterotrimeric G protein and phospholipase C beta4 (PLCbeta4). We examined the development of CF synapses in three strains of mutant mice lacking mGluR1, the alpha subunit of Gq (Galphaq) and PLCbeta4, respectively. These three strains of mutant mice have persistent multiple CF innervation of PCs due to the defect during the third postnatal week, which is similar to the phenotype of previously reported PKCgamma mutant mice. These results suggest that signal transduction cascade that involves mGluR1, Gq, PLCbeta4 and PKCgamma is crucial for CF synapse elimination during the third postnatal week.(3) Analyzes of GluRdelta2 deficient mice :We analyzed cerebellar parallel fiber (PF) and CF synapse formation in mutant mice lacking the glutamate receptor delta2 (GluRdelta2), the PC specific ionotropic GluR.By using electron microscopic and electrophysiological methods, we demonstrated that the density of PF to PC synapses in the GluRdelta2 mutant was less than half of that of the wild type. In addition, we found that CFs formed ectopic synapses onto distal dendrites of PCs, which is presumably due to impaired PF to PC synapse formation.

(1)小脑攀爬纤维突触反应的生后发育：采用电生理学方法观察了小鼠小脑攀爬纤维（CF）对浦肯野细胞（PC）突触反应的发育变化。多个CFs支配的PC百分比在出生后的前两周显著下降。爬行纤维反应在出生后的第一周有较慢的上升时间，并表现出更大程度的双脉冲抑郁症比成熟的动物。我们已经证明，在大鼠的成对脉冲抑制主要是由于减少递质释放CF突触前末梢。(2)对mGluR1、Galphaq和PLC β 4缺失小鼠的分析：认为1型代谢型谷氨酸受体（mGluR1）通过Gq型异源三聚体G蛋白和磷脂酶C β 4（PLC β 4）在PC中激活蛋白激酶C γ（PKC γ）。我们分别研究了缺乏mGluR1、Gq α亚基（Galphaq）和PLC β 4的三种突变小鼠的CF突触发育。这三个品系的突变小鼠具有持久的多CF神经支配的PC由于缺陷在出生后第三周，这是类似于先前报道的PKC γ突变小鼠的表型。这些结果表明，涉及mGluR1，Gq，PLC β 4和PKC γ的信号转导级联是至关重要的CF突触消除在出生后第三周。(3)GluRdelta2缺陷小鼠的分析：我们分析了缺乏谷氨酸受体delta2（GluRdelta2，PC特异性离子型GluR）的突变小鼠小脑平行纤维（PF）和CF突触的形成。通过电子显微镜和电生理方法，我们证明了GluRdelta2突变小鼠PF到PC突触的密度不到野生型的一半。此外，我们发现CFs在PC的远端树突上形成异位突触，这可能是由于PF到PC突触形成受损所致。

项目成果

狩野 方伸: "脳・神経機能の解明〜ミクロからマクロまで" 真鍋俊也、片山正寛/編、羊土社, 9 (1997)

Masanobu Kano：“大脑和神经功能的阐明 - 从微观到宏观”Toshiya Manabe，Masahiro Katayama/eds.，Yodosha，9（1997）

Kano, M.: "A bridge between cerebellar long-term depression and discrete motor learning : Studies on gene knockout mice." Behavioral and Brain Sciences. 19. 488-490 (1996)

Kano, M.：“小脑长期抑郁和离散运动学习之间的桥梁：对基因敲除小鼠的研究。”

Kano, M., Aiba, A., Chen, C., Stanton, M.E., Fox, G.D.and Tonegawa, S.: "Cerebellar long-term depression and motor learning : a study on mGluR1 mutant mice." In : Brain Processes and Memory. K.Ishikawa, J.L.McGaugh & H.Sakata, (eds). Excerpta Medica Inter

Kano, M.、Aiba, A.、Chen, C.、Stanton, M.E.、Fox, G.D. 和 Tonekawa, S.：“小脑长期抑郁和运动学习：对 mGluR1 突变小鼠的研究。”

Offermanns, S., Hashimoto, K., Watanabe, M., Sun, W., Kurihara, H., Thompson, R.F., Inoue, Y., Kano, M.and Simon, M.I.: "Impaired motor coordination and persistent multiple climbing fiber innervation of cerebellar Purkinje cells in mice lacking Galphaq."

Offermanns, S.、Hashimoto, K.、Watanabe, M.、Sun, W.、Kurihara, H.、Thompson, R.F.、Inoue, Y.、Kano, M. 和 Simon, M.I.：“运动协调受损和持续性多发性硬化症

Tempia, F.: "The fractional calcium current through neuronal AMPA receptor channels with a‘low'calcium permeability." J.Neurosci.15. 456-466 (1996)

Tempia, F.：“通过具有‘低’钙渗透性的神经元 AMPA 受体通道的钙电流分数。”J.Neurosci.15 (1996)。