Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of amaygdala, cortex and hippocampus from rats subjected to immobilization stress

ABSTRACT: Prolonged stress has adverse consequences for neurons in the hippocampus (HIPP). The amygdala (AMY) is a brain region that is similar to HIPP across many measures, suggesting that chronic stress might modulate AMY and HIPP function in similar ways. However, studies addressing this issue have produced surprising results. For example, a regimen of chronic stress shown to produce atrophy in HIPP neurons caused dendritic branching in AMY neurons. These and other data have revealed that excessive stress induces fundamentally opposing processes in the AMY and HIPP, such that AMY function is facilitated by levels of stress that produce deleterious effects in HIPP. The mechanisms that contribute to the opposing responses of these brain regions to chronic stress are unknown. Such knowledge may suggest novel directions for pharmacological interventions to protect the HIPP from stress-mediated damage.,We will determine gene expression patterns in the hippocampus and amygdala under basal and stressful conditions, with a particular interest in those genes that are differentially regulated across the two regions. ,We hypothesize that genes that are oppositely regulated in the amygdala and hippocampus after stress mediate the opposing functional consequences of chronic stress in these two brain regions. Moreover, genes which are differentially expressed in these regions under basal conditions may underlie the distinct responses of these regions to stress.,Rats will receive either 30sec of handling (Control group; n=15) or 3hr of immobilization stress (Stress group; n=15) each day for 14 consecutive days. This stress paradigm has previously been shown to produce opposing effects on dendritic morphology and region-dependent behaviors for the hippocampus versus amygdala. Twenty-four hours after the last stress or handling session, the rats will be overanaesthetized, and the brain will be removed and placed in ice-cold buffer. Tissue will be rapidly dissected from the basolateral complex of the amygdala and the CA3 region of the hippocampus of both hemispheres, flash frozen in liquid nitrogen, and stored at -80C until further processing. The tissue from each brain region will be pooled across groups, yielding four samples (Control-Hippocampus, Control-Amygdala, Stress-Hippocampus, and Stress-Amygdala). Total RNA will be extracted using standard methods, and sent to the centers. Each sample will be run in triplicate, utilizing a total of 12 Affymetrix Rat Genome U34A gene chips. A triplicate array assay of pooled samples has previously been shown to both substantially increase the sensitivity of detecting genes of interest and reduce the variability associated with individual microarrays. In addition, the large number of rats used in each group will reduce the variability in gene expression associated with individual responses to chronic stress, as well as variability due to slight anatomical differences in the tissue extracted from each rat.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Elizabeth Salomon

PROVIDER: E-GEOD-2870 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Prolonged stress has adverse consequences for neurons in the hippocampus (HIPP). The amygdala (AMY) is a brain region that is similar to HIPP across many measures, suggesting that chronic stress might modulate AMY and HIPP function in similar ways. However, studies addressing this issue have produced surprising results. For example, a regimen of chronic stress shown to produce atrophy in HIPP neurons caused dendritic branching in AMY neurons. These and other data have revealed that excessive stress induces fundamentally opposing processes in the AMY and HIPP, such that AMY function is facilitated by levels of stress that produce deleterious effects in HIPP. The mechanisms that contribute to the opposing responses of these brain regions to chronic stress are unknown. Such knowledge may suggest novel directions for pharmacological interventions to protect the HIPP from stress-mediated damage. We will determine gene expression patterns in the hippocampus and amygdala under basal and stressful conditions, with a particular interest in those genes that are differentially regulated across the two regions. We hypothesize that genes that are oppositely regulated in the amygdala and hippocampus after stress mediate the opposing functional consequences of chronic stress in these two brain regions. Moreover, genes which are differentially expressed in these regions under basal conditions may underlie the distinct responses of these regions to stress. Rats will receive either 30sec of handling (Control group; n=15) or 3hr of immobilization stress (Stress group; n=15) each day for 14 consecutive days. This stress paradigm has previously been shown to produce opposing effects on dendritic morphology and region-dependent behaviors for the hippocampus versus amygdala. Twenty-four hours after the last stress or handling session, the rats will be overanaesthetized, and the brain will be removed and placed in ice-cold buffer. Tissue will be rapidly dissected from the basolateral complex of the amygdala and the CA3 region of the hippocampus of both hemispheres, flash frozen in liquid nitrogen, and stored at -80C until further processing. The tissue from each brain region will be pooled across groups, yielding four samples (Control-Hippocampus, Control-Amygdala, Stress-Hippocampus, and Stress-Amygdala). Total RNA will be extracted using standard methods, and sent to the centers. Each sample will be run in triplicate, utilizing a total of 12 Affymetrix Rat Genome U34A gene chips. A triplicate array assay of pooled samples has previously been shown to both substantially increase the sensitivity of detecting genes of interest and reduce the variability associated with individual microarrays. In addition, the large number of rats used in each group will reduce the variability in gene expression associated with individual responses to chronic stress, as well as variability due to slight anatomical differences in the tissue extracted from each rat. Keywords: dose response

Project description:Fear conditioning (FC) is a behavioral paradigm that measures an animalâs ability to learn fear related information. FC is measured by pairing a mild foot-shock with the surroundings in which the shock was received. Upon being placed back in the context, mice exhibit freezing behavior, which is a species-specific response to fear. We have used selective breeding to produce lines of mice with high or low levels of freezing behavior. We are able to identify alleles that govern the genetic variability for FC by using chromosomal markers in these lines. Using microarrays, we will identify differences in gene expression in two key brain regions: amygdala and hippocampus. Gene expression differences and data regarding chromosomal regions involved in the behavior will be compared to identify particular genes that are both differentially expressed and whose expression is governed by alleles that fall into critical chromosomal regions.,We will compare gene expression in the amygdala and hippocampus (brain regions known to be relevant to fear behavior) from the two lines of mice and use Bayesian statistics in an effort to identify gene expression that affects fear behavior.,We hypothesize that selection has acted in part by changing the frequency of alleles that cause differential expression of key genes in the amygdala and hippocampus of our selected lines. Selective breeding changes the frequency of trait relevant (FC) alleles. A relevant allele is expected to increase in one selected line and decrease in the oppositely selected line. Some trait relevant alleles are expected cause changes in the level of expression at particular genes.,Amygdala and hippocampus will be rapidly dissected out of experimentally naÃ¯ve mice from each line. NaÃ¯ve mice will be used for expression studies since the behavior of the mice in the FC test can be reliably anticipated due to their lineage. We have practiced these procedures, and can accurately and reproducibly remove these regions in less than 5 minutes. Different mice will be used to collect each brain region, since the dissection of hippocampus disrupts the removal of amygdala. We will collect enough samples from each region to accommodate a total of 6 microarrays per brain region, per line, thus we will use a total of 24 microarrays. We anticipate that a single brain region will be sufficient to for a microarray. However, we propose to utilize three samples per microarray, because this will reduce variability due to environmental factors and due to slight variability in our dissection procedures. Once this tissue is removed, we will isolate RNA for shipment to the Microarray consortium. We will also collect spleens from each subject as a source of genomic DNA, in order to permit direct comparison of genotype and expression phenotypes. Once we have the results of the microarray analysis, we use WebQTL.org to identify the chromosomal locations of alleles that are know to influence the expression of genes for which we have found differential expression. We will then superimpose this information on trait relevant chromosomal regions identified from our selected lines. This will allow us to rapidly identify genes which may account for genetic variability in FC due to differential expression. Such genes will then be subjected to further study.

Project description:Sexual selection involves mate preference behavior and is a critical determinant for natural selection and evolutionary biology. Previously an environmental compound (fungicide vinclozolin) was found to promote epigenetic transgenerational inheritance of modified mate selection characteristics in all progeny for three generations after exposure of a gestating female. The current study investigated gene networks involved in various regions of the brain that correlated with the mate preference behavior altered in F3-Vinclozolin lineage animals. Statistically significant correlations of differentially expressed gene clusters and modules were identified to associate with specific mate preference behaviors. This novel systems biology approach identified critical gene networks involved in mate preference behavior and demonstrated the ability of environmental factors to promote epigenetic transgenerational inheritance of this altered evolutionary biology determinant. Combined observations elucidate the potential molecular control of mate preference behavior and suggests environmental epigenetics can have a role in evolutionary biology. We used Affymetrix Rat Gene 1.0 ST microarrays to determine genes expressed differentially in F3 Vinclozolin lineage male or female rats' 6 brain areas - amygdala (Amy), hippocampus (Hipp), olfactory bulb (OlfB), cingulate cortex (CngCtx), entorhinal cortex (EnCtx), and preoptic area-anterior hypothalamus (POAH) - due to Vinclozolin treatments of their grand-grandmothers (F0). For each of 6 brain areas of male or female rats (female: amygdala (F-Amy), cingulate cortex (F-CngCTX), enterorhinal cortex (F-EnCTX), hippocampus (F-Hipp), olfactory bulbs (F-OlfB), and preoptic area-anterior hypothalamus (F-POAH); male: amygdala (M-Amy), cingulate cortex (M-CngCTX), enterorhinal cortex (M-EnCTX), hippocampus (M-Hipp), olfactory bulbs (M-OlfB), and preoptic area-anterior hypothalamus (M-POAH)), RNA samples from 2 treatment groups - F3 Control lineage (Con) or F3 Vinclozolin lineage (Vin) - were compared to each other. Each of treatment groups contained 4-6 biological replicas for each brain region. RNA for each replica was isolated from an individual animal in order to compare to individual animal mate preference behavior studied with the same rats before sacrifice. Totally, 132 RNA samples from 24 animals (6 male F3 Control, 6 male F3 Vinclozolin,6 female F3 Control, and 6 female F3 Vinclozolin) were isolated and studied.

Project description:Fear conditioning (FC) is a behavioral paradigm that measures an animal's ability to learn fear related information. FC is measured by pairing a mild foot-shock with the surroundings in which the shock was recieved. Upon being placed back in the context, mice exhibit freezing behavior, which is a species-specific response to fear. We have previously used selective breeding to produce lines of mice with high or low levels of freezing behavior. This experiment is a replication of a previous experiment that produced lines of mice with high or low levels of freezing behavior. These lines derive from different progenitor mouse strains. We are able to identify alleles that govern the genetic variability for FC by using chromosomal markers in these selected lines. Using microarrays, we will identify differences in gene expression in two key brain regions: amygdala and hippocampus. Gene expression differences and data regarding chromosomal regions involved in the behavior will be compared to identify particular genes that are both differentially expressed and whose expression is governed by alleles that fall into critical chromosomal regions.,We will compare gene expresion in the amygdala and hippocampus (brain regions known to be relevant to fear behavior) from the these two lines of mice and to the those in the previous experiment. Bayesian statistics will be used in an effort to identify gene expression that affects fear behavior.,We hypothesize that selection has acted in part by changing the frequency of alleles that cause differential expression of key genes in the amygdala and hippocampus of our selected lines. Slective breeding changes the frequency of trait relevand (FC) alleles. A relevant allele is expected to increas in one selected line and decrease in the oppositely selected line. Some trait relevant alleles are expected to cause changes in the level of expression at particular genes.,Amygdala and hippocampus will be rapidly dissected out of experimentally naÃ¯ve mice from each line. NaÃ¯ve mice will be used for expression studies since the behavior of the mice in the FC test can be reliably anticipated due to their lineage. We have practiced these procedures, and can accurately and reproducibly remove these regions in less than 5 minutes. Different mice will be used to collect each brain region, since the dissection of hippocampus disrupts the removal of amygdala. We will collect enough samples from each region to accommodate a total of 6 microarrays per brain region, per line, thus we will use a total of 24 microarrays. We anticipate that a single brain region will be sufficient to for a microarray. However, we propose to utilize three samples per microarray, because this will reduce variability due to environmental factors and due to slight variability in our dissection procedures. Once this tissue is removed, we will isolate RNA for shipment to the Microarray consortium. We will also collect spleens from each subject as a source of genomic DNA, in order to permit direct comparison of genotype and expression phenotypes. Once we have the results of the microarray analysis, we use WebQTL.org to identify the chromosomal locations of alleles that are know to influence the expression of genes for which we have found differential expression. We will then superimpose this information on trait relevant chromosomal regions identified from our selected lines. This will allow us to rapidly identify genes which may account for genetic variability in FC due to differential expression. Such genes will then be subjected to further study.

Project description:Background: Examining transcriptional regulation by existing antidepressants in key neural circuits implicated in depression, and understanding the relationship to transcriptional mechanisms of susceptibility and natural resilience, may help in the search for new therapeutics. Further, given the heterogeneity of treatment response in human populations, examining both treatment response and non-response is critical. Methods: We compared the effects of a conventional monoamine-based tricyclic antidepressant, imipramine (14 daily injections), and a rapidly acting, experimental, non-monoamine-based antidepressant, ketamine (single injection), in mice subjected to chronic social defeat stress, a validated model of depression, and used RNA-sequencing to analyze transcriptional profiles associated with susceptibility, resilience and antidepressant response and non-response in prefrontal cortex (PFC), nucleus accumbens, hippocampus, and amygdala. Results: We identified approximately equal numbers of responder and non-responder mice following ketamine or imipramine treatment. Ketamine induced more expression changes in hippocampus than other brain regions; imipramine induced more expression changes in nucleus accumbens and amygdala. Transcriptional profiles in ketamine and imipramine responders were most similar in PFC, where the least transcriptional regulation occurred for each drug. Non-response reflected both the lack of response-associated gene expression changes and unique gene regulation. In responders, both drugs reversed susceptible associated transcriptional changes as well as induced resilient associated transcription in PFC, with effects varying by drug and brain region studied. Conclusions: We generated a uniquely large resource of gene expression data in four inter-connected limbic brain regions implicated in depression and its treatment with imipramine or ketamine. Our analyses highlight the PFC as a key site of common transcriptional regulation by both antidepressant drugs and in both reversing susceptibility and inducing resilience associated molecular adaptations. In addition, we found region-specific effects of each drug suggesting both common and unique effects of imipramine versus ketamine. mRNA profiles of susceptibility to chronic social defeat stress as well as treatment response were generated across 4 separate brain regions, with a sample size of 3-5 per group.

Project description:A cardinal symptom of Major Depressive Disorder (MDD) is the disruption of circadian patterns. Yet, to date, there is no direct evidence of circadian clock dysregulation in the brains of MDD patients. Circadian rhythmicity of gene expression has been observed in animals and peripheral human tissues, but its presence and variability in the human brain was difficult to characterize. Here we applied time-of-death analysis to gene expression data from high-quality postmortem brains, examining 24-hour cyclic patterns in six cortical and limbic regions of 55 subjects with no history of psychiatric or neurological illnesses ('Controls') and 34 MDD patients. Our dataset covered ~12,000 transcripts in the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (AnCg), hippocampus (HC), amygdala (AMY), nucleus accumbens (NAcc) and cerebellum (CB). Several hundred transcripts in each region showed 24-hour cyclic patterns in Controls, and >100 transcripts exhibited consistent rhythmicity and phase-synchrony across regions. Among the top ranked rhythmic genes were the canonical clock genes BMAL1(ARNTL), PER1-2-3, NR1D1(REV-ERB), DBP, BHLHE40(DEC1), and BHLHE41(DEC2). The phasing of known circadian genes was consistent with data derived from other diurnal mammals. Cyclic patterns were much weaker in MDD brains, due to shifted peak timing and potentially disrupted phase relationships between individual circadian genes. This is the first transcriptome-wide analysis of cyclic patterns in the human brain and demonstrates a rhythmic rise and fall of gene expression in regions outside of the suprachiasmatic nucleus in control subjects. The description of its breakdown in MDD suggest novel molecular targets for treatment of mood disorders. Sample collection, including human subject recruitment and characterization, tissue dissection, and RNA extraction, was described previously (see Evans 2003 Neurobiol Dis 14:240-250, Li 2004 Biol Psychiatry 55:346-352). RNA samples for different regions came from the same set of brains from 86 control subjects. Sample size varied by region: AnCg (n=70 controls), DLPFC (n=83), CB (n=51), AMY (n=32), HC (n=63) and NAcc (n=66). Many of the samples were run on two or more chips, resulting in the following chip counts for each region: AnCg = 124, DLPFC = 161, CB = 79, AMY = 62, HC = 108 and NaCC = 136. We ran each sample on at least two microarrays using the Affymetrix U133-A or U133Plus-v2 GeneChips, however, we only used the U133A part of the U133Plus-v2 GeneChip in our analysis. We applied RMA (Robust Multi-array Analysis) (see Irizarry 2003 Biostatistics 4:249-264, Irizarry 2003 Nucleic Acids Res 31:e15) to summarize probe set expression levels, using a custom Chip Definition File, resulting in expression data for 11,911 ENTREZ transcripts. Microarray data for each region were analyzed separately. All downstream analyses were performed in R. Details of the data processing, including data cleaning and normalization, are located in the Supplementary Materials (section 1). After data filtering, 1,424 microarrays remained, corresponding to 776 unique RNA samples in six regions.

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Transcription profiling of amaygdala, cortex and hippocampus from rats subjected to immobilization stress

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