Redila V A, Christie B R
Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, Canada V6T 1Z4.
Neuroscience. 2006;137(4):1299-307. doi: 10.1016/j.neuroscience.2005.10.050. Epub 2005 Dec 9.
Neurogenesis is a constitutive activity in the adult dentate gyrus whereby new cells are created in the subgranular zone, before becoming neurons in the dentate gyrus granule cell layer. New granule cells are thought to migrate from the subgranular zone outwards to the edge of the cell layer as they mature. In these experiments we examined the dendritic morphology of granule cells in the subgranular zone, and the inner and outer regions of the granule cell zone in Sprague-Dawley rats with low and high rates of neurogenesis. In animals with lower rates of neurogenesis, the number of primary dendrites, degree of dendritic complexity and total dendritic length was lowest in cells located in the subgranular zone, higher in inner granule cell zone neurons, and highest in outer granule cell zone granule cells. Subgranular zone granule cells typically extended one primary dendrite and had a simple, immature dendritic tree, while granule cells in the outer granule cell zone had an increased number of primary dendrites, greater dendritic complexity, and greater total dendritic length. Animals that engaged in voluntary exercise showed increased neurogenesis, and the proportion of cells with one or two primary dendrites was increased in all of the granule cell zones. Despite having fewer primary processes, these cells showed enhanced dendritic complexity and an overall increase in their total dendritic length. These results indicate that granule cell dendritic morphology may be indicative of the age and position of a cell in the granule cell layer, but that in animals with increased rates of neurogenesis, the proportion of cells exhibiting what is considered an immature phenotype is increased throughout the all regions of the dentate gyrus cell layer.
神经发生是成年齿状回中的一种固有活动，在此过程中，新细胞在颗粒下层产生，然后在齿状回颗粒细胞层成为神经元。新的颗粒细胞在成熟时，被认为是从颗粒下层向外迁移至细胞层边缘。在这些实验中，我们研究了神经发生速率低和高的Sprague-Dawley大鼠颗粒下层、颗粒细胞层内部和外部区域的颗粒细胞的树突形态。在神经发生速率较低的动物中，位于颗粒下层的细胞的初级树突数量、树突复杂性程度和总树突长度最低，颗粒细胞层内部神经元的这些指标较高，而颗粒细胞层外部的颗粒细胞最高。颗粒下层的颗粒细胞通常伸出一根初级树突，具有简单、不成熟的树突分支，而颗粒细胞层外部的颗粒细胞的初级树突数量增加、树突复杂性更高且总树突长度更长。进行自愿运动的动物神经发生增加，并且在所有颗粒细胞区域中，具有一根或两根初级树突的细胞比例增加。尽管这些细胞的初级分支较少，但它们的树突复杂性增强且总树突长度总体增加。这些结果表明，颗粒细胞的树突形态可能表明其在颗粒细胞层中的年龄和位置，但在神经发生速率增加的动物中，整个齿状回细胞层各区域中表现出所谓不成熟表型的细胞比例增加。
