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Unfortunately, survivors of traumatic stress exposure (TSE) frequently develop adverse posttraumatic neuropsychiatric sequelae (APNS) such as chronic pain and stress/depressive symptoms. Increasing evidence indicates that there is a 'window of opportunity' following TSE in which therapeutic interventions are most effective against APNS, yet mechanisms accounting for this observation are poorly understood. Here, we aimed to better understand such mechanisms by generating snapshots of the transcriptional landscape in the early aftermath of TSE across tissues and time. Adult rats were exposed to a TSE model, single prolonged stress (SPS). Then, eight tissues (hypothalamus, left and right hippocampus, amygdala, dorsal root ganglia, spinal cord, heart, and muscle) were isolated from these animals at 2, 24, and 72 hours after SPS and in unexposed controls (n=6 per group). mRNA expression from deep sequencing was used to identify differentially expressed genes (DEGs) and biological pathways enriched over time. In all tissues except the amygdala, the highest number of DEGs was observed 2-hours post-SPS, but DEGs were detected at all timepoints and in all tissues. Some transcripts were differentially expressed in a consistent manner across multiple tissues at a time point (e.g. Fkbp5, 2 hours post-SPS), while others had tissue- or region-specific expression patterns. Stress system pathways were most represented at 2-hours post-SPS, then stress/circadian/inflammatory pathways at 24-hours, and inflammatory pathways at 72-hours. Together these findings provide insights into post-TSE transcriptional landscape dynamics and suggest specific intervention windows of opportunity. Future validation is needed across sex, age, stressor, and cell type.

Abstract: Chronic posttraumatic pain (CPTP) is common after traumatic stress exposure (TSE) and disproportionately burdens women. We previously showed across 3 independent longitudinal cohort studies that, in women, increased peritraumatic 17β-estradiol (E2) levels were associated with substantially lower CPTP over 1 year. Here, we assessed this relationship in a fourth longitudinal cohort and also assessed the relationship between E2 and CPTP at additional time points post-TSE. Furthermore, we used a well-validated animal model of TSE to determine whether exogenous E2 administration protects against mechanical hypersensitivity. Using nested samples and data from the Advancing Understanding of RecOvery afteR traumA study (n = 543 samples, 389 participants), an emergency department-based prospective study of TSE survivors, we assessed the relationship between circulating E2 levels and CPTP in women and men using multivariate repeated-measures mixed modeling. Male and ovariectomized female Sprague Dawley rats were exposed to TSE and administered E2 either immediately after or 3 days post-TSE. Consistent with previous results, we observed an inverse relationship between peritraumatic E2 and longitudinal CPTP in women only (β = -0.137, P = 0.033). In animals, E2 protected against mechanical hypersensitivity in female ovariectomized rats only if administered immediately post-TSE. In conclusion, peritraumatic E2 levels, but not those at post-TSE time points, predict CPTP in women TSE survivors. Administration of E2 immediately post TSE protects against mechanical hypersensitivity in female rats. Together with previous findings, these data indicate that increased peritraumatic E2 levels in women have protective effects against CPTP development and suggest that immediate post-TSE E2 administration in women could be a promising therapeutic strategy for reducing risk of CPTP., (Copyright © 2024 International Association for the Study of Pain.)

Chronic post-traumatic musculoskeletal pain (CPTP) is a common outcome of traumatic stress exposure. Biological factors that influence the development of CPTP are poorly understood, though current evidence indicates that the hypothalamic-pituitary-adrenal (HPA) axis plays a critical role in its development. Little is known about molecular mechanisms underlying this association, including epigenetic mechanisms. Here, we assessed whether peritraumatic DNA methylation levels at 248 5'-C-phosphate-G-3' (CpG) sites in HPA axis genes (FKBP5, NR3C1, CRH, CRHR1, CRHR2, CRHBP, POMC) predict CPTP and whether identified CPTP-associated methylation levels influence expression of those genes. Using participant samples and data collected from trauma survivors enrolled into longitudinal cohort studies (n = 290), we used linear mixed modeling to assess the relationship between peritraumatic blood-based CpG methylation levels and CPTP. A total of 66 (27%) of the 248 CpG sites assessed in these models statistically significantly predicted CPTP, with the three most significantly associated CpG sites originating from the POMC gene region (ie, cg22900229 [β = .124, P < .001], cg16302441 [β = .443, P < .001], cg01926269 [β = .130, P < .001]). Among the genes analyzed, both POMC (z = 2.36, P = .018) and CRHBP (z = 4.89, P < .001) were enriched in CpG sites significantly associated with CPTP. Further, POMC expression was inversely correlated with methylation levels in a CPTP-dependent manner (6-months NRS<4: r = -.59, P < .001; 6-months NRS ≥ 4: r = -.18, P = .2312). Our results suggest that methylation of HPA axis genes including POMC and CRHBP predict risk for and may contribute to vulnerability to CPTP. PERSPECTIVE: Peritraumatic blood levels of CpG methylation sites in HPA axis genes, particularly CpG sites in the POMC gene, predict CPTP development. This data substantially advances our understanding of epigenetic predictors and potential mediators of CPTP, a highly common, morbid, and hard-to-treat form of chronic pain., (Copyright © 2023 United States Association for the Study of Pain, Inc. Published by Elsevier Inc. All rights reserved.)

Background: The hypothalamus plays a key role in the stress response. While early life stress (ELS) increases susceptibility to psychiatric disorders including major depressive disorder (MDD), acute stress during adulthood can also precipitate MDD after ELS., Aim: Here, we tested the expression of miRNAs following ELS and susceptibility to depression-like behavior and whether sex or acute stress exacerbates this response. We also tested whether environmental enrichment (Enr) promotes early life and adult behavioral stress resilience and its effect on hypothalamic miRNA and gene expression. Following rat maternal separation (MS) as an ELS model, Enr from weaning through adulthood, and restraint (RS) as acute adult stress, we tested both animal behavior and miRNA expression in the hypothalamus. Target genes and their enrichment and ontology were analyzed using bioinformatic tools. Target gene expression changes were tested using qPCR, and miRNA promoter methylation was studied using methylated-DNA immunoprecipitation qPCR., Results: MS, Enr, RS, and sex altered hypothalamic miRNAs, including several previously reported in MS literature: miRs-29, - 124, - 132, - 144, - 504. Sex had a significant effect on the greatest number of miRNAs. Also, Enr reversed downregulation of miR-29b-1-5p and -301b-3p in MS. qPCR showed that MAPK6 and MMP19, targets of miR-301b-3p, were upregulated in MS and reversed by Enr. Additionally, miR-219a was hypermethylated in MS coinciding with decreased miR-219a expression., Conclusions: This study found that sex plays a critical role in the hypothalamic miRNA response to both ELS and acute stress, with males expressing greater changes following postnatal stress. Moreover, enrichment significantly altered behavior as well as hypothalamic miRNA expression and their gene targets. Because of its role as the initiator of the autonomic stress response and connection to hedonic and motivational behavior, the hypothalamic miRNA landscape may significantly alter both the short and long-term behavioral response to stress., (© 2021. The Author(s).)

Aims: The aim of this study was to assess regional- and sex-dependent changes in miRNA expression resulting from early-life stress (ELS). Materials and methods: Small RNA sequencing was used to determine sex-dependent changes in miRNAs after maternal separation, a rodent model of ELS, across the prefrontal cortex, amygdala and hippocampus. Results: Maternal separation induced anhedonia and altered miRNA expression in a sex-dependent manner, particularly in the prefrontal cortex and hippocampus. Gene ontology revealed that these miRNAs target genes with brain-specific biological functions. Conclusion: Using a network approach to explore miRNA signaling across the brain after ELS, regional differences were highlighted as key to studying the brain's stress response, which indicates that sex is critical for understanding miRNA-mediated ELS-induced behavior.

Background: The underlying neurobiology of early-life stress (ELS)-induced major depressive disorder is not clearly understood., Methods: In this study, we used maternal separation (MS) as a rodent model of ELS and tested whether microRNAs (miRNAs) target serotonin genes to regulate ELS-induced depression-like behavior and whether this effect is sex dependent. We also examined whether environmental enrichment prevents susceptibility to depression- and anxiety-like behavior following MS and whether enrichment effects are mediated through serotonin genes and their corresponding miRNAs., Results: MS decreased sucrose preference, which was reversed by enrichment. Males also exhibited greater changes in forced swim climbing and escape latency tests only following enrichment. S lc6a4 and H tr1a were upregulated in the frontal cortex following MS. In male MS rats, enrichment slightly reversed H tr1a expression to levels similar to control rats. miR-200a-3p and miR-322-5p, which target SLC6A4 , were decreased by MS, but not significantly. An HTR1A -targeting miRNA, miR-320-5p, was also downregulated by MS and showed slight reversal by enrichment in male animals. miR-320-5p targeting of H tr1a was validated in vitro using SHSY neuroblastoma cell lines., Conclusions: Altogether, this study implicates miRNA interaction with the serotonin pathway in ELS-induced susceptibility to depression-related reward deficits. Furthermore, because of its recovery by enrichment in males, miR-320 may represent a viable sex-specific target for reward-related deficits in major depressive disorder., (© 2021 The Authors.)