Inserm U862, Neurocentre Magendie, 146 rue Léo Saignat, 33077 Bordeaux, France.
Eur J Neurosci. 2010 Dec;32(12):1989-94. doi: 10.1111/j.1460-9568.2010.07514.x.
The supraoptic nuclei of the hypothalamus display a remarkable anatomical plasticity during lactation, parturition and chronic dehydration, conditions associated with massive neurohypophysial hormone secretion. This structural remodeling is characterized by a pronounced reduction of the astrocytic coverage of oxytocin neurons, resulting in an increase in the number and extent of directly juxtaposed neuronal surfaces. Although the exact role played by such an anatomical remodeling in the physiology of the hypothalamo-neurohypophysial system is still unknown, several findings obtained over the last decade indicate that synaptic and extrasynaptic transmissions are impacted by these structural changes. We review these data and try to extrapolate how such changes at the cellular level might affect the overall activity of the system. One repercussion of the retraction of glial processes is the accumulation of glutamate in the extracellular space. This build-up of glutamate causes an increased activation of pre-synaptic metabotropic glutamate receptors, which are negatively coupled to neurotransmitter release, and a switch in the mode of action of pre-synaptic kainate receptors that control GABA release. Finally, the range of action of substances released from astrocytes and acting on adjacent magnocellular neurons is also affected during the anatomical remodeling. It thus appears that the structural plasticity of the hypothalamic magnocellular nuclei strongly affects neuron-glial interactions and, as a consequence, induces significant changes in synaptic and extrasynaptic transmission.
下丘脑的视上核在哺乳期、分娩期和慢性脱水期间表现出显著的解剖可塑性，这些条件与大量神经垂体激素分泌有关。这种结构重塑的特征是星形胶质细胞对催产素神经元的覆盖明显减少，导致直接毗邻的神经元表面数量和范围增加。尽管这种解剖重塑在下丘脑-神经垂体系统生理学中的确切作用仍不清楚，但过去十年的几项发现表明，突触和 extrasynaptic 传递受到这些结构变化的影响。我们回顾了这些数据，并试图推断这种细胞水平的变化如何影响系统的整体活动。神经胶质过程回缩的一个后果是谷氨酸在细胞外空间的积累。谷氨酸的积累导致突触前代谢型谷氨酸受体的过度激活，而这些受体与神经递质释放呈负偶联，以及控制 GABA 释放的突触前 kainate 受体作用模式的转变。最后，在解剖重塑过程中，从星形胶质细胞释放并作用于相邻大细胞神经元的物质的作用范围也受到影响。因此，似乎下丘脑大细胞核的结构可塑性强烈影响神经元-神经胶质相互作用，并因此导致突触和 extrasynaptic 传递的显著变化。
