Project description:The dentate gyrus (DG) of the hippocampus is one of major targets for antidepressant treatments. Our recent research has revealed that selective serotonin reuptake inhibitor (SSRI) treatment causes a long-lasting change in the phenotypes of mature dentate granule neurons to immature state in adult mouse DG. However, it is unknown whether this M-bM-^@M-^\dematurationM-bM-^@M-^] of DG is a common effect of antidepressant treatments and what mechanisms underlie it. Using electroconvulsive stimulation (ECS), a model of highly effective and fast-acting antidepressant therapy, here we show that neural stimulation via ECS induces rapid and lasting dematuration of granule neurons in DG. A single or few times of stimulation transiently reduced mature marker expression and mature synaptic functions. Repetitive stimulation converted this transient dematuration into a stable form lasting more than 1 month. Dematured granule neurons showed higher excitability, and an increase in GABA-mediated inhibition by the benzodiazepine diazepam prevented the lasting maintenance phase of dematuration without affecting the initial induction phase. Our study suggests that dematuration of DG is a common cellular mechanism underlying effects of different types of antidepressant treatments, and demonstrate a novel role for excitation/inhibition balance in bidirectional regulation of the state of neuronal maturation in the adult brain. Mice were decapitated after the 11 times of ECS (or Sham) or 4 weeks treatment of fluoxetine (or vehicle) at a dose of 22 mg/kg. The brains were sliced and the frequency facilitation of mossy fiber synapse was measured in each sample. The samples which exhibited low frequency facilitation were selected to be used as dematured DG (n = 3) and the dentate gyrus was dissected from each sample. Total RNA was extracted by using an RNeasy micro kit (Qiagen) and the samples of the same groups were put together. From each group, 100 ng of total RNA was amplified with 3M-bM-^@M-^YIVT Express kit (Affymetrix, Inc., Santa Clara, CA, USA). All samples were hybridized to the GeneChip mouse genome 430A 2.0 array (Affymetrix, Inc.), and the microarray suite 5.0 of the Affymetrix gene chip operating software was used for the analysis of the GeneChip data.

Project description:We sought to find molecular signatures of the SGZ cell types, and to characterize the molecular pathways and transcription factor cascades that define the neurogenic niche. We used laser capture microdissection and DNA microarrays to profile gene expression in the inner (SGZ) and outer portions of the dentate gyrus (DG). Since the vast majority of the cells in the DG are mature granule cells, we compared the expression of the inner and outer portions to reveal molecular markers for the less numerous populations of the SGZ. This data set is part of a larger study assessing conserved molecular signatures of neurogenesis in the hippocampal subgranular zone of rodents and primates. Using a combination of selective SGZ transcriptional profiling with laser microdissection and DNA microarrays as well as in situ hybridization (ISH), we developed an extensive molecular characterization of the mouse SGZ, identifying 367 genes enriched in the SGZ compared to mature granule neurons. These genes displayed a wide range of cellular expression patterns reflecting the cellular milieu of the SGZ, including progenitor and dividing cells, immature granule cells, astrocytes, oligodendrocytes, and GABAergic interneurons. We next used a comparable microarray data set in rhesus monkey that profiled the SGZ across postnatal development to identify genes related to developmentally regulated granule cell neurogenesis. The rhesus monkey SGZ showed highly significant similarity to mouse, whereas network analysis of these data identified SGZ-enriched gene sets with different temporal profiles reflecting differential time-courses for maturation of glia and granule neurons. One neurogenesis-related gene network showed a steady decrease in expression across postnatal rhesus development from birth to adulthood. This temporal pattern is highly correlated with the number of proliferating cells in the dentate gyrus, and the neurogenic transcription factors Sox4 and Sox11 are central hub genes for this gene network. A number of the genes in this network showed a similar postnatal downregulation in mouse, suggesting a general conservation of molecular mechanisms underlying developmental and adult neurogenesis in rodents and primates. Primate data available at: http://www.blueprintnhpatlas.org/ Brains from 10- to 11-week-old C57BL/6 male mice housed in three conditions (no running, 4 days of running, 30 days of running) were sectioned and the dentate gyrus was isolated. For each brain, the inner granule cell layer (containing the subgranular zone) and outer GCL were separated using laser capture microdissection, and RNA from each region was collected and processed as described in the protocols.

Project description:We sought to find molecular signatures of the SGZ cell types, and to characterize the molecular pathways and transcription factor cascades that define the neurogenic niche. We used laser capture microdissection and DNA microarrays to profile gene expression in the inner (SGZ) and outer portions of the dentate gyrus (DG). Since the vast majority of the cells in the DG are mature granule cells, we compared the expression of the inner and outer portions to reveal molecular markers for the less numerous populations of the SGZ. This data set is part of a larger study assessing conserved molecular signatures of neurogenesis in the hippocampal subgranular zone of rodents and primates. Using a combination of selective SGZ transcriptional profiling with laser microdissection and DNA microarrays as well as in situ hybridization (ISH), we developed an extensive molecular characterization of the mouse SGZ, identifying 367 genes enriched in the SGZ compared to mature granule neurons. These genes displayed a wide range of cellular expression patterns reflecting the cellular milieu of the SGZ, including progenitor and dividing cells, immature granule cells, astrocytes, oligodendrocytes, and GABAergic interneurons. We next used a comparable microarray data set in rhesus monkey that profiled the SGZ across postnatal development to identify genes related to developmentally regulated granule cell neurogenesis. The rhesus monkey SGZ showed highly significant similarity to mouse, whereas network analysis of these data identified SGZ-enriched gene sets with different temporal profiles reflecting differential time-courses for maturation of glia and granule neurons. One neurogenesis-related gene network showed a steady decrease in expression across postnatal rhesus development from birth to adulthood. This temporal pattern is highly correlated with the number of proliferating cells in the dentate gyrus, and the neurogenic transcription factors Sox4 and Sox11 are central hub genes for this gene network. A number of the genes in this network showed a similar postnatal downregulation in mouse, suggesting a general conservation of molecular mechanisms underlying developmental and adult neurogenesis in rodents and primates. Primate data available at: http://www.blueprintnhpatlas.org/

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Hippocampal neuronal dematuration as a common effect of antidepressant treatments

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