Hippocampal neuronal dematuration as a common effect of antidepressant treatments
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ABSTRACT: 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 “dematuration” 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.
Project description:The dentate gyrus (DG) of the hippocampus is one of major targets for antidepressant treatments. 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 time 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. We compared the activity-dependent neuronal responsiveness in the DG between a single ECS and repeated ECS.
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:Neuronal activity-dependent gene expression plays important roles in neural plasticity. We use electroconvulsive stimulation (ECS) as an in vivo model for neuronal activation to identify genes that are regulated by neuronal activity. Dentate gyri (DG) were microdissected 4 hours after sham or ECS treatment for gene expression profiling. 4 total samples were analysed (2 for each condition). Averaged expression values between sham and ECS samples were pair-wise compared.
Project description:Neuronal activity-dependent gene expression plays important roles in neural plasticity. We use electroconvulsive stimulation (ECS) as an in vivo model for neuronal activation to identify genes that are regulated by neuronal activity. Dentate gyri (DG) were microdissected 4 hours after sham or ECS treatment for gene expression profiling.
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:Neuronal activity initiates transcriptional programs that shape long-term changes in plasticity. Although neuron subtypes differ in their plasticity response, most activity-dependent transcription factors are broadly expressed across different neuron subtypes and brain regions. Thus, how regional and neuronal subtype-specific plasticity are established on the transcriptional level remains poorly understood. Here, we report that the developmental transcription factor Sox11 is induced in mature neurons upon hippocampal circuit activity and that this activity-dependent expression occurs exclusively in the dentate gyrus (DG) of the hippocampus. In addition, we show that Sox11 can modify synaptic plasticity and intrinsic excitability of DG granule cell neurons as well as the expression of plasticity-related genes. We propose that Sox11 is a DG-specific activity-dependent gene and might play a role in fine tuning regional plasticity in the hippocampal circuit.
Project description:We investigated the transcriptome of dentate gyrus (DG) granule cells in postmortem hippocampus from 79 subjects with mental illness (schizophrenia, bipolar disorder, major depression) or non-psychiatric controls.
Project description:Neural stem cells (NSCs) generate new neurons throughout life in two distinct areas of the mammalian brain: the subventricular zone (SVZ) lining the lateral ventricles and the hippocampal dentate gyrus (DG). How gene expression signatures differ among NSCs and immature neurons within and between these adult neurogenic regions is unknown. We isolated NSCs and their progeny using transgenic mice expressing GFP under the control of the Sox2 promoter (labeling NSCs) and transgenic mice expressing DsRed under the control of the doublecortin (Dcx) promoter (labeling immature neurons). Comparison of the transcriptomes of SOX2+ cells derived from both neurogenic areas revealed that NSCs are highly similar but that functionally significant differences in gene expression exist: IGF2, which is expressed only in SOX2+ cells in the DG but not in the SVZ, is required for proliferation of DG-derived but not SVZ-derived NSCs. Gene expression profiles strongly diverged in immature neurons, and we provide evidence that ephrinB3, which was up-regulated only in the DG but not in the SVZ during neuronal differentiation, regulates the survival of newborn granule cells. Thus, the data provided here show that stem cell populations in the adult DG and SVZ are similar but have unique properties that manifest themselves later during neural differentiation, resulting in distinct neuronal populations Hippocampi and SVZ from 6 week old DCX-DsRed and Sox2-GFP Reporter mice were dissected and cell sorted using FACS. cDNA were generated and analysed using Agilent Platform.
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/
Project description:Mutations in the JMJD3 (KDM6B) chromatin regulator are causally associated with autism spectrum disorder and syndromic intellectual disability, but the neurodevelopmental roles of this histone 3 lysine 27 (H3K27) demethylase are poorly understood. Neural stem cells (NSCs) in the hippocampal dentate gyrus (DG) generate new granule neurons throughout life, and deficits in DG neurogenesis are associated with cognitive and behavioral problems. Here we show that Jmjd3 is required for the establishment of adult neurogenesis in the mouse DG. Conditional deletion of Jmjd3 in embryonic DG precursors results in an adult hippocampus that is essentially devoid of NSCs. While early postnatal mice with Jmjd3-deletion have near normal numbers of DG NSCs, at later stages, Jmjd3-deleted NSCs fail to propagate normally. In addition to the loss of NSCs during postnatal development, neurogenesis from Jmjd3-deleted NSCs is impaired, corresponding to defective neurogenic gene expression. Without Jmjd3, NeuroD2 and Bcl11b(Ctip2) are not properly expressed and exhibit increased levels of H3K27me3, underscoring the role of Jmjd3 in the regulation of transcription for neuronal differentiation. Thus, these data indicate that Jmjd3 plays dual roles in postnatal DG neurogenesis, being critical for the establishment of the NSC pool as well as the differentiation of young DG granule neurons. More broadly, our results suggest a neurodevelopmental link between JMJD3 mutations and hippocampal dysfunction, providing new insights into how mutations in chromatin regulators may contribute to learning disorders.