Coutinho Victoria, Knöpfel Thomas
Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, RIKEN, Saitama, Japan.
Neuroscientist. 2002 Dec;8(6):551-61. doi: 10.1177/1073858402238514.
Over the last two decades, glutamate has been established as the main excitatory neurotransmitter in the mammalian brain. Glutamate released from synapses activates ion channel-forming receptors at postsynaptic cells and consequently mediates fast postsynaptic potentials. These receptors are termed ionotropic glutamate receptors (iGluRs). The subsequent discovery of metabotropic glutamate receptors (mGluRs) revealed that glutamate can also mediate slow synaptic potentials, modulate ion channels, and directly couple to GTP binding proteins. In contrast to the iGluRs, the mGluRs possess seven transmembrane domains and a large intracellular C-terminus that involves interactions with a variety of other intracellular signaling systems. Eight functionally distinct mGluR subtypes are known to be localized to specific neuron types at presynaptic and/or postsynaptic membranes. Their physiological functions involve the generation of slow excitatory and inhibitory synaptic potentials, modulation of synaptic transmission, synaptic integration, and plasticity. The classical role of glutamate as a fast excitatory synaptic transmitter was largely extended by mGluRs acting as a neuromodulator and even as an activator of inhibitory mechanisms at certain synapses.
在过去二十年中，谷氨酸已被确立为哺乳动物大脑中的主要兴奋性神经递质。从突触释放的谷氨酸激活突触后细胞上形成离子通道的受体，从而介导快速的突触后电位。这些受体被称为离子型谷氨酸受体（iGluRs）。代谢型谷氨酸受体（mGluRs）的后续发现表明，谷氨酸还可以介导缓慢的突触电位、调节离子通道，并直接与GTP结合蛋白偶联。与离子型谷氨酸受体不同，代谢型谷氨酸受体具有七个跨膜结构域和一个大的细胞内C末端，该末端涉及与多种其他细胞内信号系统的相互作用。已知有八种功能不同的代谢型谷氨酸受体亚型定位于突触前和/或突触后膜的特定神经元类型。它们的生理功能包括产生缓慢的兴奋性和抑制性突触电位、调节突触传递、突触整合和可塑性。谷氨酸作为快速兴奋性突触递质的经典作用在很大程度上被代谢型谷氨酸受体扩展，后者在某些突触中作为神经调节剂，甚至作为抑制机制的激活剂。
