Viola Giordano G, Rodrigues Letícia, Américo João C, Hansel Gisele, Vargas Rafael S, Biasibetti Regina, Swarowsky Alessandra, Gonçalves Carlos A, Xavier Léder L, Achaval Matilde, Souza Diogo O, Amaral Olavo B
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, 2600-Anexo, 90035-003 Porto Alegre, RS, Brazil.
Brain Res. 2009 Jun 5;1274:47-54. doi: 10.1016/j.brainres.2009.04.007. Epub 2009 Apr 15.
Environmental enrichment is known to induce plastic changes in the brain, including morphological changes in hippocampal neurons, with increases in synaptic and spine densities. In recent years, the evidence for a role of astrocytes in regulating synaptic transmission and plasticity has increased, and it is likely that morphological and functional changes in astrocytes play an important role in brain plasticity. Our study was designed to evaluate changes in astrocytes induced by environmental enrichment in the CA1 region of the hippocampus, focusing on astrocytic density and on morphological changes in astrocytic processes. After 8 weeks of environmental enrichment starting at weaning, male CF-1 mice presented no significant changes in astrocyte number or in the density of glial fibrillary acidic protein (GFAP) immunoreactivity in the stratum radiatum. However, they did present changes in astrocytic morphology in the same region, as expressed by a significant increase in the ramification of astrocytic processes measured by the Sholl concentric circles method, as well as by an increase in the number and length of primary processes extending in a parallel orientation to CA1 nerve fibers. This led astrocytes to acquire a more stellate morphology, a fact which could be related to the increase in hippocampal synaptic density observed in previous studies. These findings corroborate the idea that structural changes in astrocytic networks are an integral part of plasticity processes occurring in the brain.
已知环境富集可诱导大脑发生可塑性变化，包括海马神经元的形态变化，突触和树突棘密度增加。近年来，星形胶质细胞在调节突触传递和可塑性方面发挥作用的证据增多，星形胶质细胞的形态和功能变化可能在大脑可塑性中起重要作用。我们的研究旨在评估海马CA1区环境富集诱导的星形胶质细胞变化，重点关注星形胶质细胞密度以及星形胶质细胞突起的形态变化。从断奶开始进行8周的环境富集后，雄性CF-1小鼠放射层的星形胶质细胞数量或胶质纤维酸性蛋白（GFAP）免疫反应性密度没有显著变化。然而，它们在同一区域的星形胶质细胞形态确实发生了变化，表现为用肖尔同心圆法测量的星形胶质细胞突起分支显著增加，以及与CA1神经纤维平行延伸的初级突起的数量和长度增加。这使得星形胶质细胞获得了更呈星状的形态，这一事实可能与先前研究中观察到的海马突触密度增加有关。这些发现证实了星形胶质细胞网络的结构变化是大脑中发生的可塑性过程不可或缺的一部分这一观点。
