Project description:Emerging evidence has shown that noncoding RNAs, particularly microRNAs (miRNAs), contribute to the pathogenesis of mood and anxiety disorders, although the molecular mechanisms are poorly understood. Here we show altered levels of miR-17-92 in adult hippocampal neural progenitors have a significant impact in neurogenesis and anxiety- and depression-related behaviors in mice. miR-17-92 deletion in adult neural progenitors causes a decrease, while its overexpression an increase of neurogenesis in the dentate gyrus, through regulating genes in the glucocorticoid pathway, especially serum- and glucocorticoid-inducible protein kinase-1 (Sgk1). miR-17-92 knockout mice show anxiety- and depression-like behaviors, whereas miR-17-92 overexpressing mice exhibit anxiolytic and antidepression-like behaviors. Furthermore, we show that miR-17-92 expression in the adult mouse hippocampus responds to chronic stress, and miR-17-92 rescues proliferation defects, induced by corticosterone, in hippocampal neural progenitors. Our study uncovers a crucial role for miR-17-92 in adult neural progenitors to regulate neurogenesis and anxiety- and depression-like behaviors.
Project description:Background: Adolescence is a critical period of vulnerability to depression, yet most evidence for the antidepressant effects of exercise derives from adult models. This study aims to investigate the effects of aerobic exercise and identify its associated molecular changes in the adolescent depression mouse model. Methods: A chronic social defeat stress (CSDS) model was established in adolescent male C57BL/6J mice to induce depression-like behaviors. Thirty-six mice were randomly assigned to three groups: control (CG), model (MG), and model plus exercise (ME). MG and ME mice were subjected to CSDS for two weeks (days 7–20), while ME mice additionally received three weeks of aerobic treadmill training covering the whole CSDS period (days 0–20). Behavioral tests were conducted on days 21–26, followed by the collection of serum and hippocampal tissues for molecular, histological, and transcriptomic analyses. Results: CSDS induced significant depression-like behaviors in adolescent male mice, including social avoidance, anhedonia, and behavioral despair, all of which were effectively alleviated by aerobic exercise. Aerobic exercise appeared to mitigate CSDS-induced neural damage and maintain hippocampal tissue integrity. Moreover, aerobic exercise increased serum levels of serotonin. Transcriptomic analysis identified 587 differentially expressed genes (DEGs). Among these genes, 59 overlapping DEGs were regulated by both CSDS and exercise, and were enriched in carbohydrate metabolism and cholinergic signaling pathways. Conclusions: Aerobic exercise alleviates depression-like behaviors in adolescent male mice, possibly by modulating hippocampal gene expression – especially in cholinergic and carbohydrate metabolism pathways – which provides potential clues to how exercise could influence peripheral monoamine levels and hippocampal structural integrity. These putative mechanisms require further investigation.
Project description:Depression is a complex and heterogeneous disorder and a leading contributor to the global burden of of disease. Most previous research has focused on individual brain regions and individual genes that contribute to depression. However, emerging evidence in both humans and animal models suggests that dysregulated circuit function and gene expression across multiple brain regions drive depressive phenotypes. Here we use a bioinformatics approach intersecting differential expression analysis with weighted gene co-expression network analysis to identify transcriptional networks that regulate susceptibility to depressive-like symptoms in mice. We performed RNA-sequencing on multiple brain regions from control animals and those either susceptible or resilient to chronic social defeat stress (CSDS) at multiple time points after defeat. We bioinformatically identified several transcriptional networks that regulate depression susceptibility, and in vivo manipulations of these networks confirmed their functional significance at the levels of gene transcription, synaptic regulation, and behavior. Our findings reveal novel transcriptional networks that control stress susceptibility and offer fundamentally new leads for antidepressant drug discovery.
Project description:Major depression is a multidimensional disorder highly prevalent in modern society. Although several classes of antidepressants (ADs) are currently available to treat depression, the effectiveness of treatment is still limited, as many patients do not show full remission; thus, there is a need to find better patients’ directed therapeutic strategies. Neuroplastic changes in several brain regions, namely in the hippocampal dentate gyrus (DG), are amongst the best correlates of depression and of ADs actions. In this study the targets and molecular mediators of chronic stress and of four ADs from different pharmacological classes (fluoxetine, imipramine, tianeptine and agomelatine) were investigated in the DG. Using the unpredictable chronic mild stress (uCMS) animal model of depression, the molecular commonalities and specificities of the ADs were determined. All ADs, except agomelatine, could reverse the behavioral deficits produced by uCMS, and the neuroplastic changes in the DG; agomelatine reversed only the anhedonic profile in the sucrose consumption test. Chronic stress induced mild but relevant molecular changes that were mostly reversed by fluoxetine, imipramine and tianeptine. Fluoxetine reduced pro-inflammatory response and increased cell metabolism pathways. Its actions were mostly dependent on molecular changes occurring in neurons. Similarities were found between imipramine and tianeptine molecular actions and targets, as both activated pathways related to cellular protection. Moreover, no particular neural cell type enrichment was found with both treatments. Agomelatine presented a very dissimilar molecular pattern impacting greatly on Rho-GTPases-related pathways in oligodendrocytes and neurons. The recognition of these molecular alterations contributes to the understanding of the processes implicated in the onset and treatment of depression and may pave the way for more effective therapeutic interventions. We compared gene expresssion in the dentate gyros of rats which were either untreated, exposed to unpredictable chronic mild stress, or exposed to the same stress and treated with either fluoxetine, imipramine, tianeptine, or agomelatine
Project description:Despite studies providing insight into the neurobiology of chronic stress, depression and anxiety, long noncoding RNA (lncRNA)-mediated mechanisms underlying the common and distinct pathophysiology of these stress-induced disorders remain nonconclusive. In a previous study, we used the chronic mild stress paradigm to separate depression-susceptible, anxiety-susceptible and insusceptible rat subpopulations. In the current study, lncRNA and messenger RNA (mRNA) expression was comparatively profiled in the hippocampus of the three stress groups using microarray technology. Groupwise comparisons identified distinct sets of lncRNAs and mRNAs associated with the three different behavioral phenotypes of the stressed rats. To investigate the regulatory roles of the dysregulated lncRNAs upon mRNA expression, correlations between the differential lncRNAs and mRNAs were first analyzed by combined use of weighted gene coexpression network analysis and ceRNA theory-based methods. Subsequent functional analysis of strongly correlated mRNAs indicated that the dysregulated lncRNAs were involved in various biological pathways and processes to specifically induce rat susceptibility or resiliency to depression or anxiety. Further intersectional analysis of phenotype-associated and drug-associated lncRNA-mRNA networks and subnetworks assisted in identifying 16 hub lncRNAs as potential targets of anti-depression/anxiety drugs. Collectively, our study established the molecular basis for understanding the similarities and differences in pathophysiological mechanisms underlying stress-induced depression or anxiety and stress resiliency, revealing several important lncRNAs that represent potentially new therapeutic drug targets for depression and anxiety disorders.
Project description:Major depression is a multidimensional disorder highly prevalent in modern society. Although several classes of antidepressants (ADs) are currently available to treat depression, the effectiveness of treatment is still limited, as many patients do not show full remission; thus, there is a need to find better patients’ directed therapeutic strategies. Neuroplastic changes in several brain regions, namely in the hippocampal dentate gyrus (DG), are amongst the best correlates of depression and of ADs actions. In this study the targets and molecular mediators of chronic stress and of four ADs from different pharmacological classes (fluoxetine, imipramine, tianeptine and agomelatine) were investigated in the DG. Using the unpredictable chronic mild stress (uCMS) animal model of depression, the molecular commonalities and specificities of the ADs were determined. All ADs, except agomelatine, could reverse the behavioral deficits produced by uCMS, and the neuroplastic changes in the DG; agomelatine reversed only the anhedonic profile in the sucrose consumption test. Chronic stress induced mild but relevant molecular changes that were mostly reversed by fluoxetine, imipramine and tianeptine. Fluoxetine reduced pro-inflammatory response and increased cell metabolism pathways. Its actions were mostly dependent on molecular changes occurring in neurons. Similarities were found between imipramine and tianeptine molecular actions and targets, as both activated pathways related to cellular protection. Moreover, no particular neural cell type enrichment was found with both treatments. Agomelatine presented a very dissimilar molecular pattern impacting greatly on Rho-GTPases-related pathways in oligodendrocytes and neurons. The recognition of these molecular alterations contributes to the understanding of the processes implicated in the onset and treatment of depression and may pave the way for more effective therapeutic interventions.
Project description:Major depressive disorder is a common mood disorder. Chronic stressful life is presumably main etiology that leads to the neuron and synapse atrophies in the limbic system. However, the intermediate molecules from stress to neural atrophy remain elusive. Mice were treated by chronic unpredictable mild stress (CUMS) until demonstrating depression-like behaviors confirmed by the tests of sucrose preference, forced swimming and Y-maze. The sequencings of microRNA and mRNA from the medial prefrontal cortices were performed in CUMS-induced depression mice versus control mice to assess the molecular profiles of major depressive disorder. In the medial prefrontal cortices of depression-like mice, the levels of mRNAs that translated the proteins for the GABAergic synapses, dopaminergic synapses, myelination, synaptic vesicle cycle and neuronal growth were downregulated. miRNAs of regulating these mRNAs are upregulated. The deterioration of GABAergic and dopaminergic synapses as well as axonal growth is associated to CUMS-induced depression.
Project description:Major depressive disorder is a common mood disorder. Chronic stressful life is presumably main etiology that leads to the neuron and synapse atrophies in the limbic system. However, the intermediate molecules from stress to neural atrophy remain elusive. Mice were treated by chronic unpredictable mild stress (CUMS) until demonstrating depression-like behaviors confirmed by the tests of sucrose preference, forced swimming and Y-maze. The sequencings of microRNA and mRNA from the medial prefrontal cortices were performed in CUMS-induced depression mice versus control mice to assess the molecular profiles of major depressive disorder. In the medial prefrontal cortices of depression-like mice, the levels of mRNAs that translated the proteins for the GABAergic synapses, dopaminergic synapses, myelination, synaptic vesicle cycle and neuronal growth were downregulated. miRNAs of regulating these mRNAs are upregulated. The deterioration of GABAergic and dopaminergic synapses as well as axonal growth is associated to CUMS-induced depression.