Girardet Clémence, Bosler Olivier
Centre de Recherche en Neurobiologie-Neurophysiologie de Marseille, France.
Biol Aujourdhui. 2011;205(3):179-97. doi: 10.1051/jbio/2011018. Epub 2011 Oct 11.
Accumulating evidence renders the dogma obsolete according to which the structural organization of the brain would remain essentially stable in adulthood, changing only in response to a need for compensatory processes during increasing age and degeneration. It has indeed become clear from investigations on various models that the adult nervous system can adapt to physiological demands by altering reversibly its synaptic circuits. This potential for structural and functional modifications results not only from the plastic properties of neurons but also from the inherent capacity of the glial cellular components to undergo remodeling as well. This is currently known for astrocytes, the major glial cells in brain which are well-recognized as dynamic partners in the mechanisms of synaptic transmission, and for the tanycytes and pituicytes which contribute to the regulation of neurosecretory processes in neurohemal regions of the hypothalamus. Studies on the neuroendocrine hypothalamus, whose role is central in homeostatic regulations, have gained good insights into the spectacular neuronal-glial rearrangements that may subserve functional plasticity in the adult brain. Following pioneering works on the morphological reorganizations taking place in the hypothalamo-neurohypophyseal system under certain physiological conditions such as dehydration and lactation, studies on the gonadotropic system that orchestrates reproductive functions have re-emphasized the dynamic interplay between neurons and glia in brain structural plasticity processes. This review summarizes the major contributions provided by these researches in the field and also addresses the question of the morphological rearrangements that occur on a 24-h basis in the central component of the circadian clock responsible for the temporal aspects of endocrine regulations. Taken together, the reviewed data highlight the close cooperation between neurons and glia in developing strategies for functional adaptation of the brain to the changing conditions of the internal and external environment.
越来越多的证据表明，大脑结构组织在成年后基本保持稳定，仅在年龄增长和退化过程中因需要补偿过程而发生变化的这一教条已过时。从对各种模型的研究中确实可以清楚地看到，成年神经系统可以通过可逆地改变其突触回路来适应生理需求。这种结构和功能修饰的潜力不仅源于神经元的可塑性，还源于神经胶质细胞成分进行重塑的内在能力。目前已知星形胶质细胞（大脑中的主要神经胶质细胞，被公认为是突触传递机制中的动态伙伴）以及参与下丘脑神经血区神经分泌过程调节的伸长细胞和垂体细胞都具有这种能力。对神经内分泌下丘脑的研究（其在稳态调节中起核心作用）使人们很好地了解了可能有助于成人大脑功能可塑性的惊人的神经元 - 神经胶质细胞重排。继在脱水和泌乳等某些生理条件下下丘脑 - 神经垂体系统发生形态重组的开创性研究之后，对协调生殖功能的促性腺系统的研究再次强调了神经元和神经胶质细胞在大脑结构可塑性过程中的动态相互作用。本综述总结了该领域这些研究的主要贡献，并探讨了负责内分泌调节时间方面的昼夜节律钟中央组件中24小时内发生的形态重排问题。综上所述，所审查的数据突出了神经元和神经胶质细胞在制定大脑功能适应内部和外部环境变化条件的策略方面的密切合作。
