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Browsing by Author "Jackson, Nateka L."

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    Differential stress induced c-Fos expression and identification of region-specific miRNA-mRNA networks in the dorsal raphe and amygdala of high-responder/low-responder rats
    Cohen, Joshua L.; Ata, Anoosha E.; Jackson, Nateka L.; Rahn, Elizabeth J.; Ramaker, Ryne C.; Cooper, Sara; Kerman, Ilan A.; Clinton, Sarah M. (2017-02)
    Chronic stress triggers a variety of physical and mental health problems, and how individuals 2 cope with stress influences risk for emotional disorders. To investigate molecular mechanisms 3 underlying distinct stress coping styles, we utilized rats that were selectively-bred for differences 4 in emotionality and stress reactivity. We show that high novelty responding (HR) rats readily 5 bury a shock probe in the defensive burying test, a measure of proactive stress coping behavior, 6 while low novelty responding (LR) rats exhibit enhanced immobility, a measure of reactive 7 coping. Shock exposure in the defensive burying test elicited greater activation of HR rats’ 8 caudal dorsal raphe serotonergic cells compared to LRs, but lead to more pronounced 9 activation throughout LRs’ amygdala (lateral, basolateral, central, and basomedial nuclei) 10 compared to HRs. RNA-sequencing revealed 271 mRNA transcripts and 33 microRNA species 11 that were differentially expressed in HR/LR raphe and amygdala. We mapped potential 12 microRNA-mRNA networks by correlating and clustering mRNA and microRNA expression and 13 identified networks that differed in either the HR/LR dorsal raphe or amygdala. A dorsal raphe 14 network linked three microRNAs which were down-regulated in LRs (miR-206-3p, miR-3559-5p, 15 and miR-378a-3p) to repression of genes related to microglia and immune response (Cd74, 16 Cyth4, Nckap1l, and Rac2), the genes themselves were up-regulated in LR dorsal raphe. In the 17 amygdala, another network linked miR-124-5p, miR-146a-5p, miR-3068-3p, miR-380-5p, miR-18 539-3p, and miR-7a-1-3p with repression of chromatin remodeling-related genes (Cenpk, 19 Cenpq, Itgb3bp, and Mis18a). Overall this work highlights potential drivers of gene-networks 20 and downstream molecular pathways within the raphe and amygdala that contribute to 21 individual differences in stress coping styles and stress vulnerabilities.
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    Genetic predisposition to high anxiety- and depression-like behavior coincides with diminished DNA methylation in the adult rat amygdala.
    McCoy, Chelsea R.; Jackson, Nateka L.; Day, Jeremy; Clinton, Sarah M. (2017-03-01)
    Understanding biological mechanisms that shape vulnerability to emotional dysfunction is critical for elucidating the neurobiology of psychiatric illnesses like anxiety and depression. To elucidate molecular and epigenetic alterations in the brain that contribute to individual differences in emotionality, our laboratory utilized a rodent model of temperamental differences. Rats bred for low response to novelty (Low Responders, LRs) are inhibited in novel situations and display high anxiety, helplessness, and diminished sociability compared to High Novelty Responder (HR) rats. Our current transcriptome profiling experiment identified widespread gene expression differences in the amygdala of adult HR/LR rats; we hypothesize that HR/LR gene expression and downstream behavioral differences stem from distinct epigenetic (specifically DNA methylation) patterning in the HR/LR brain. Although we found similar levels of DNA methyltransferase proteins in the adult HR/LR amygdala, next-generation sequencing analysis of the methylome revealed 793 differentially methylated genomic sites between the groups. Most of the differentially methylated sites were hypermethylated in HR versus LR, so we next tested the hypothesis that enhancing DNA methylation in LRs would improve their anxiety/depression-like phenotype. We found that increasing DNA methylation in LRs (via increased dietary methyl donor content) improved their anxiety-like behavior and decreased their typically high levels of Forced Swim Test (FST) immobility; however, dietary methyl donor depletion exacerbated LRs' high FST immobility. These data are generally consistent with findings in depressed patients showing that treatment with DNA methylation-promoting agents improves depressive symptoms, and highlight epigenetic mechanisms that may contribute to individual differences in risk for emotional dysfunction.
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    A paternal methyl donor depleted diet leads to increased anxiety- and depression-like behavior in adult rat offspring
    McCoy, Chelsea R.; Jackson, Nateka L.; Brewer, Rachel L.; Moughnyeh, Mohamad M.; Smith, Daniel L.; Clinton, Sarah M. (Portland Press, 2018-08-31)
    Epigenetic mechanisms such as DNA methylation elicit lasting changes in gene expression and likely mediate gene–environment interactions that shape brain development, behavior, and emotional health. Myriad environmental factors influence DNA methylation, including methyl donor content in the paternal diet, could influence methylation in offspring via changes in the paternal germ line. The present study examines the effects of paternal methyl donor dietary deficiency on offspring’s emotional behaviors, including anxiety, social interaction, and depression-like behavior. We previously found that rats bred to display high levels of anxiety- and depression-like behavior exhibit diminished DNA methylation in the amygdala. We also observed that depleting dietary methyl donor content exacerbated the rats’ already high levels of anxiety- and depression-like behavior. Here we sought to determine whether paternal dietary methyl donor depletion elicits intergenerational effects on first generation (F1) offspring’s behavior (potentially triggering a similar increase in anxiety- and/or depression-like behavior). Thus, adult male rats prone to high anxiety/depression-like behavior, were fed either a methyl donor depleted (DEP) or control (CON) diet for 5 weeks prior to mating. They were paired with females and resultant F1 male offspring were subjected to a behavioral test battery in adulthood. F1-DEP offspring showed a similar behavioral profile to the F0 males, including greater depression-like behavior in the forced swim test (FST) and increased anxiety-like behavior in the open field test (OFT). Future work will interrogate molecular changes in the brains of F1 offspring that mediate these intergenerational effects of paternal methyl donor dietary content on offspring emotional behavior.