Gozlan Henri, Ben-Ari Yehezkel
INMED-INSERM U29, 163 route de Luminy, BP 13, 13273 Marseille cedex 9, France.
Cereb Cortex. 2003 Jun;13(6):684-92. doi: 10.1093/cercor/13.6.684.
In hippocampal CA1 pyramidal neurons, GABAergic synapses are established before glutamatergic synapses. GABAergic interneurons should therefore develop and acquire synapses at an earlier stage to provide the source for GABAergic synapses. We now report that this is indeed the case. At birth and in utero, when nearly all pyramidal neurons are not yet functional, most interneurons have already either GABAergic only or GABAergic and glutamatergic postsynaptic currents. At birth, the morphological maturation of interneurons parallels their individual functional responses. In addition, the formation of functional interneurons types appears to be a sequential process. Interneurons that innervate other interneurons acquire GABA(A) synapses before peridendritic interneurons, but also before perisomatic interneurons that are not yet functional at birth. Therefore, interneurons are the source and the targets of the first synapses formed in the developing circuit. Since GABA was shown to be excitatory in utero, interneurons provide all the excitatory drive at a time when the principal cells are silent. They could therefore play a central role in the formation of the cortical circuit at early developmental stages.
在海马体CA1锥体神经元中，GABA能突触在谷氨酸能突触之前建立。因此，GABA能中间神经元应在更早阶段发育并形成突触，以提供GABA能突触的来源。我们现在报告情况确实如此。在出生时和子宫内，当几乎所有锥体神经元尚未发挥功能时，大多数中间神经元已经具有仅GABA能或GABA能和谷氨酸能的突触后电流。出生时，中间神经元的形态成熟与其各自的功能反应平行。此外，功能性中间神经元类型的形成似乎是一个连续的过程。支配其他中间神经元的中间神经元在树突周中间神经元之前获得GABA(A)突触，但也在出生时尚未发挥功能的胞体周围中间神经元之前获得。因此，中间神经元是发育中回路中形成的第一批突触的来源和靶点。由于GABA在子宫内被证明是兴奋性的，在主要细胞沉默时，中间神经元提供了所有的兴奋性驱动。因此，它们可能在早期发育阶段的皮质回路形成中发挥核心作用。
