Piet Richard, Poulain Dominique A, Oliet Stéphane H R
INSERM U.378 and Université Victor Segalen, 1, rue Camille Saint Saëns, 33077 Bordeaux cedex, France.
J Physiol Paris. 2002 Apr-Jun;96(3-4):231-6. doi: 10.1016/s0928-4257(02)00010-4.
One of the functions of astroglial cells in the central nervous system is to clear synaptically-released glutamate from the extracellular space. This is performed thanks to specific transporters of the excitatory amino acid expressed on their surface. The way by which astrocytic glutamate uptake contributes to synaptic transmission has been investigated via numerous experimental approaches but has never been addressed under conditions where neuroglial interactions are physiologically modified. Recently, we took advantage of the neuroglial plastic properties of the hypothalamo-neurohypophysial system to examine the consequences of a physiological reduction in the astrocytic coverage of neurons on glutamatergic synaptic transmission. This experimental model has brought some insights on the physiological interactions between glial cells and neurons at the level of the synapse. In particular, it has revealed that the degree of glial coverage of neurons influences glutamate concentration at the vicinity of excitatory synapses and, as a consequence, affects the level of activation of presynaptic glutamate receptors. Astrocytes, therefore, appear to contribute to the regulation of neuronal excitability by modulating synaptic efficacy at glutamatergic nerve terminals.
中枢神经系统中星形胶质细胞的功能之一是清除细胞外空间中通过突触释放的谷氨酸。这一过程借助其表面表达的兴奋性氨基酸特异性转运体得以实现。尽管通过众多实验方法对星形胶质细胞摄取谷氨酸促进突触传递的方式进行了研究，但从未在神经胶质相互作用发生生理性改变的条件下进行探讨。最近，我们利用下丘脑 - 神经垂体系统的神经胶质可塑性特性，研究神经元星形胶质细胞覆盖范围生理性减少对谷氨酸能突触传递的影响。该实验模型为突触水平上胶质细胞与神经元之间的生理相互作用提供了一些见解。特别是，它揭示了神经元的胶质细胞覆盖程度会影响兴奋性突触附近的谷氨酸浓度，进而影响突触前谷氨酸受体的激活水平。因此，星形胶质细胞似乎通过调节谷氨酸能神经末梢的突触效能来参与神经元兴奋性的调节。
