Neuroscience Program, Wellesley College, Wellesley, MA 02481, USA.
Dev Neurobiol. 2011 May;71(5):351-61. doi: 10.1002/dneu.20864.
New neurons are incorporated throughout life into the brains of many vertebrate and non-vertebrate species. This process of adult neurogenesis is regulated by a variety of external and endogenous factors, including environmental enrichment, which increases the production of neurons in juvenile mice and crayfish. The primary goal of the present study was to exploit the spatial separation of the neuronal precursor cell lineage in crayfish to determine which generation(s) of precursors is altered by environmental conditions. Further, in crayfish, an intimate relationship between the 1 generation neuronal precursors (stem cells) and cells circulating in the hemolymph has been proposed (Zhang et al., 2009). Therefore, a second goal was to assess whether environmental enrichment alters the numbers or types of cells circulating in the hemolymph. We find that neurogenesis in the brains of sexually differentiated procambarid crayfish is enhanced by environmental enrichment as previously demonstrated by Sandeman and Sandeman (2000) in young, sexually undifferentiated . We also show that environmental enrichment increases the cell cycle rate of neuronal stem cells. While there was no effect of environment on the overall numbers of cells circulating in the hemolymph, enrichment resulted in increased expression of glutamine synthetase, a marker of the neuronal stem cells, in a small percentage of circulating cells; there was little or no expression of this enzyme in hemolymph cells extracted from deprived animals. Thus, environmental enrichment influences the rate of neuronal stem cell division in adult crayfish, as well as the composition of cells circulating in the hemolymph.
新的神经元在许多脊椎动物和无脊椎动物物种的大脑中终身被整合。这种成年神经发生过程受到各种外部和内在因素的调节，包括环境丰富，它增加了幼年老鼠和小龙虾中神经元的产生。本研究的主要目的是利用小龙虾神经元前体细胞谱系的空间分离来确定哪些代的前体细胞受环境条件的改变。此外，在小龙虾中，1 代神经元前体细胞（干细胞）与循环在血淋巴中的细胞之间存在密切关系（Zhang 等人，2009）。因此，第二个目标是评估环境丰富是否改变了循环在血淋巴中的细胞的数量或类型。我们发现，性分化 procambarid 小龙虾大脑中的神经发生被环境丰富所增强，正如 Sandeman 和 Sandeman（2000）在年轻、未分化的小龙虾中所证明的那样。我们还表明，环境丰富增加了神经元干细胞的细胞周期率。虽然环境对循环在血淋巴中的细胞总数没有影响，但丰富导致循环细胞中的谷氨酸合成酶表达增加，谷氨酸合成酶是神经元干细胞的标志物，在一小部分循环细胞中；在剥夺动物提取的血淋巴细胞中，这种酶几乎没有表达。因此，环境丰富影响成年小龙虾神经元干细胞分裂的速度，以及循环在血淋巴中的细胞的组成。
