Ontogenesis of central excitatory synaptic receptors

中枢兴奋性突触受体的个体发生

• 批准号: 04044092
• 负责人: TAKAHASHI Tomoyuki
• 金额: $ 9.28万
• 依托单位: University of Tokyo (1993)Kyoto University (1992)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04044092/
• 关键词: Slice; Cerebellar Granule Cells; Patch Clamp; NMDA Receptors; EPSC; Ontogenesis; Mg^<2+>; 小脳; 顆粒細胞

We studied ontogenic changes of NMDA receptors (NMDAR) in cerebellar granule cells by using patch clamp techniques applied to thin slices of brain tissues. By applying NMDA from outside to granule cells in whole-cell recording mode, we found that external granule cells before migration already express NMDA receptors. The NMDA responses of external granule cells showed typical voltage-dependent Mg blockade reported for NMDARs. Single channel recordings of NMDAR currents in outside-out patches excised from external granule cells showed 50 pS main conductance and 40 pS subconductance states as commonly described for NMDARs. These NMDARs may contribute to cell migration by providing cells with pathways for Ca entry. It has been reported that NMDA antagonist can suppress granule cell migration. Functional NMDAR density judged from the amplitude of NMDA-induced whole-cell current was low in external granule cells compared with that in internal granule cells. The density of migrating granule cell was intermediate, indicating that the density of NMDAR increase as the cells migrate (Farrant et al., Nature 1994, in press).We also found that the NMDARs in internal granule cells undergo developmental changes. At the early postnatal period (< 2 weeks), NMDAR-induced single channel currents were predominantly 50/40 ps in conductances. As animals grow older, chances of observing the NMDAR channel currents of 30/20 pS increased. From molecular studies it has reported that the mRNAs encoding the NMDAR in cerebellar granule cells switches from II_B to II_C at around 3 weeks postnatally. The II_B/I NMDARs expressed in Xenopus oocytes from cRNAs had 50/40 pS, whereas the II_C/I NMDARs expressed similarly had 30/20 pS. We conclude that II_B/II_C switching occurs in native tissue, thereby changing the channel properties (Farrant et al., Nature 1994, in press).

应用脑片膜片钳技术研究了小脑颗粒细胞NMDAR的个体发育变化。在全细胞记录模式下，通过将NMDA从外部作用于颗粒细胞，我们发现迁移前的外部颗粒细胞已经表达了NMDA受体。NMDARs外颗粒细胞的NMDA反应表现为典型的电压依赖性镁拮抗反应。NMDAR电流的单通道记录显示，NMDAR的主电导为50ps，次电导为40ps，这是NMDAR通常所描述的。这些NMDAR可能通过为细胞提供钙进入途径而促进细胞迁移。有报道称，NMDA拮抗剂可以抑制颗粒细胞的迁移。从NMDA诱导的全细胞电流的幅度来看，外颗粒细胞的功能性NMDAR密度低于内颗粒细胞。迁移颗粒细胞的密度居中，表明NMDAR的密度随着细胞的迁移而增加(Farant等人，自然，1994年出版)。我们还发现，内部颗粒细胞中的NMDAR经历了发育变化。在出生后早期(2周)，NMDAR诱发的单通道电流主要在电导中为50/40ps。随着动物年龄的增长，观察到30/20pS的NMDAR通道电流的机会增加。分子研究表明，小脑颗粒细胞中编码NMDAR的mRNAs在出生后3周左右由II_B转变为II_C。表达于非洲爪哇卵母细胞中的II_B/I NMDAR为50/40 pS，而表达的II_C/I NMDAR为30/20 pS。我们得出结论，II_B/II_C转换发生在天然组织中，从而改变了通道特性(Farant等人，自然，1994年出版)。

项目成果

Hayashi Y: "Role of a metabotropic glutamate receptor in synaptic modulation in the accessory olfactory bulb." Nature. 366. 687-690 (1993)

Hayashi Y：“代谢型谷氨酸受体在副嗅球突触调节中的作用。”

Kobayashi,S: "Whole-cell properties of temperature-sensitive neurons in rat hypothalamic slices." Proc.R.Soc.Lond B.251. 89-94 (1993)

Kobayashi，S：“大鼠下丘脑切片中温度敏感神经元的全细胞特性。”

Feldmeyer,D.,Farrant,M.,TAKAHASHI,T.&Cull-Candy,S.G.: "NMDA receptors of rat orebellar grchnule cells deering postnatal developnant." XXXIInd International Congress of Physiologiol Scienes Glasgow,Abstrat. (1993)

费尔德迈耶，D.，法兰特，M.，高桥，T.

Farrant M: "NMDA receptor channels of developing granule cells in rat thin cerebellar slices." Journal of Physiology. 467. 272P (1993)

Farrant M：“大鼠小脑切片中发育中的颗粒细胞的 NMDA 受体通道。”

Feldmeyer,D.,Farrant,M.,TAKAHASHI,T.&S.G.Cull-Candy: "NMDA receptor channels in rat cerebellar goonrle cells duning ealy postnatal declopment" J.Physiol.(London). (1993)

费尔德迈耶，D.，法兰特，M.，高桥，T.