Marqués-Marí Ana-Isabel, Nacher Juan, Crespo Carlos, Gutièrrez-Mecinas María, Martínez-Guijarro Francisco-José, Blasco-Ibáñez José-Miguel
Departamento de Biología Celular, Unidad de Neurobiología, Facultad de Ciencias Biológicas, Universidad de Valencia, E-46.100 Burjasot, Spain.
Hippocampus. 2007;17(7):510-24. doi: 10.1002/hipo.20290.
The objective of this work is to check whether the input from the mossy cells to the inner molecular layer is necessary for the integration and maturation of the newly generated granule cells of the dentate gyrus (DG) in mice, and if after status epilepticus the sprouting of the mossy fibers can substitute for this projection. Newly generated cells were labeled by administration of 5-bromo-deoxyuridine either before or after pilocarpine administration. The neuronal loss in the hippocampus after administration of pilocarpine combined with scopolamine and diazepam seemed restricted to the hilar mossy cells. The maturation of the granule cells was studied using immunohistochemistry for calretinin and NeuN in combination with detection of 5-bromo-deoxyuridine. The sprouting of the mossy fibers was detected using Timm staining for zinc-rich boutons. In normal conditions, granule cells took about 2 weeks to lose the immature marker calretinin. After the loss of the mossy cells, newly generated granule cells remained expressing calretinin for more than a month, until the sprouting of the mossy fibers substituted for the projection of the mossy cells in the inner molecular layer of the DG. Therefore, a proper pattern of connectivity is necessary for the normal development and integration of newly generated granule cells in the adult brain. In a changed environment they cannot adapt transforming in other cell types; simply they are unable to mature. The sprouting of the mossy fibers, although aberrant and a probable source of epileptic activity, may be important for the correct physiology of the granule cells, restoring a likeness of normality in their connective environment. The survival of granule cells incorporated as mature neurons was increased after pilocarpine when compared with normal conditions. Thus, it is likely that the reorganization of the circuitry after the loss of the mossy cells facilitates the survival and incorporation of the newly generated granule cells.
这项工作的目的是检查苔藓细胞向分子内层的输入对于小鼠齿状回（DG）新生颗粒细胞的整合和成熟是否必要，以及癫痫持续状态后苔藓纤维的发芽是否可以替代这种投射。在毛果芸香碱给药之前或之后给予5-溴脱氧尿苷来标记新生细胞。毛果芸香碱联合东莨菪碱和地西泮给药后海马中的神经元损失似乎仅限于门区苔藓细胞。使用钙视网膜蛋白和NeuN的免疫组织化学结合5-溴脱氧尿苷的检测来研究颗粒细胞的成熟。使用富含锌的终扣的Timm染色来检测苔藓纤维的发芽。在正常情况下，颗粒细胞大约需要2周时间才能失去未成熟标记物钙视网膜蛋白。苔藓细胞缺失后，新生颗粒细胞在一个多月的时间里一直表达钙视网膜蛋白，直到苔藓纤维的发芽替代了DG分子内层中苔藓细胞的投射。因此，适当的连接模式对于成体脑中新生颗粒细胞的正常发育和整合是必要的。在变化的环境中，它们无法适应转化为其他细胞类型；简单来说，它们无法成熟。苔藓纤维的发芽虽然异常且可能是癫痫活动的来源，但可能对颗粒细胞的正确生理功能很重要，在其连接环境中恢复正常状态。与正常情况相比，毛果芸香碱给药后作为成熟神经元整合的颗粒细胞的存活率增加。因此，苔藓细胞缺失后电路的重组可能促进了新生颗粒细胞的存活和整合。
