Caractérisation fonctionnelle et moléculaire du circuit dopaminergique dans un modèle de la dépression

Authors: Quessy, Francis
Advisor: Lévesque, Martin; Labonté, Benoit
Abstract: Background: Our ability to develop the cognitive strategies required to deal with daily-life stress is regulated by region-specific neuronal networks. Experimental evidences suggest that prolonged stress in mice induces depressive-like behaviors via morpho-functional and molecular changes of the mesolimbic and mesocortical dopaminergic pathways. Yet, the transcriptional programs underlying these changes are still poorly understood and whether they affect males and females similarly is unknown. Methods: We used chronic social defeat stress (CSDS) to induce depressive-like behaviors in male and female mice. Density of the mesolimbic and cortical projections was assessed via IHC combined with Scholl analysis along with the staining of the activity-dependent marker pERK in the ventral tegmental area (VTA), nucleus accumbens (NAc) and medial prefrontal cortex (mPFC). DAT-IRES-CRE-RiboTag transgenic mice were used to isolate from mRNA dopaminergic axons and somas and analyze gene expression through RNAseq. Transcriptional profiles were analyzed through differential expression combined with gene network analyses. Results: Social stress decreased the density of dopaminergic axonal projections to the mPFC but not the NAc of susceptible mice. This was accompanied by decreased pERK expression in the VTA of susceptible but not resilient mice. Our differential expression and gene network analyses revealed soma- and axon-specific transcriptional signatures associated with stress susceptibility and resilience in males and females. We identified soma and axon specific key regulators of sex-specific gene networks underlying the expression of susceptibility and resilience in males and females. Conclusion: Our results indicate that social defeat stress impacts the mesolimbic and mesocortical pathways differently in males and females by altering the transcriptional programs regulating somatic and axonal plasticity differently. These sex-specific changes are likely to underlie the morpho-functional changes induced by CSDS and contribute to the expression of susceptibility or resilience to social stress in both sexes.
Document Type: Mémoire de maîtrise
Issue Date: 2021
Open Access Date: 15 February 2021
Permalink: http://hdl.handle.net/20.500.11794/68165
Grantor: Université Laval
Collection:Thèses et mémoires

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