Chronic Stress and Abdominal Pain: Novel Mechanisms


Principal Investigator: John W Wiley
Abstract: DESCRIPTION (provided by applicant): Chronic Stress and Abdominal Pain: Novel Mechanisms Chronic stress activates the Hypothalamic-Pituitary-Adrenal (HPA) axis and is a known inducer of abdominal pain. Recent reports indicate that chronic psychological stress causes changes in epigenetic regulation of gene function in CNS regions associated with memory and mood. Epigenetics refers to stable and/or heritable changes in gene function without changes in the DNA sequence via DNA methylation, histone modification and chromatin remodeling. The field of epigenetics has emerged rapidly in the past decade based on seminal studies demonstrating genome-wide distribution of methylation and acetylation sites in primary cells and human cell lines. It is unknown whether chronic stress regulates peripheral pain pathways via epigenetic mechanisms. The endovanilloid transient receptor potential (TRP) pathway plays a pivotal role in pain transmission and the TRPV1 receptor is known to be regulated by endocannabinoids (CB) acting on CB1 receptors which inhibit TRPV1 function. Chronic stress down-regulates the function of the CB pathway resulting in up-regulation of TRPV1 receptor function and abdominal pain. We will examine the hypothesis that chronic stress induces visceral pain via epigenetic regulation of CB1 and TRPV1 receptors in a region- and cel- specific manner in dorsal root ganglion (DRG) neurons innervating pelvic organs but not the somatosensory distribution to the lower extremities. Specifically, our preliminary data support two highly novel hypotheses: 1. Chronic intermittent stress promotes DNMT1-mediated methylation of glucocorticoid receptor (GR) promoter sites resulting in decreased GR expression that is linked to reduced levels and function of the anti-nociceptive endocannabinoid CB1 receptor, and enhances histone acetylation linked to increased expression and function of the pro-nociceptive endovanilloid TRPV1 receptor in dorsal root ganglion (DRG) neurons;and 2. Chronic stress-induced, corticosterone (CORT)-mediated epigenetic changes are region- and cell-specific, and "hardwired" to nociceptive DRGs innervating the GI tract (colon) vs. somatosensory (sciatic nerve) distribution. The hardwired expression pattern predisposes nociceptive neurons innervating the GI tract to hyperalgesia in response to colorectal distension in the setting of chronic intermittent stress. These studies will include the application of cuttin-edge methods to identify putative regulatory CpG methylation sites at the promoters of stress response genes and chromatin immunoprecipitation (ChIP) analysis of relevant histone modification targets. The subpopulation of nociceptive neurons will be identified using both immunohistochemical markers with retrograde labeling and laser capture microscopy to harvest distinct populations of DRG neurons in conjunction with quantitative single-cell PCR of relevant targets. Confirmation of the role of specific receptors and signal transduction pathways to the changes observed in CB and TRP pathways will be confirmed using targeted delivery of gene silencing (si-RNA) reagents in situ and correlation of these interventions with behavior, e.g. visceral motor response to colorectal distension. We will also examine whether the formation of CB1-TRPV1 receptor complexes plays a role in stress-associated visceral hyperalgesia in DRG neurons and transfected cells using FRET/TIRF microscopy and electrophysiological recordings. Clarifying the mechanisms underlying epigenetic regulation of chronic stress-induced visceral pain will have a significant impact on our understanding of how pain pathways are regulated and, likely, the management of functional pain disorders affecting the GI tract.
Funding Period: 2013-04-01 - 2018-02-28
more information: NIH RePORT

Detail Information

Research Grants30

  1. Understanding Pain of Gastrointestinal Origin in Women that Serve in OEF/OIF
    Beverley Greenwood-Van Meerveld; Fiscal Year: 2013
    ..Moreover, we will examine whether rats exposed to ELS show altered behavioral responses to chronic stress in adulthood compared to age-matched controls ..
  2. Endogenous Cannabinoids and Brain Function
    Aron H Lichtman; Fiscal Year: 2013
    ..Ultimately, the knowledge gained from this basic research will yield novel therapeutic targets that can be exploited with the pharmacological agents developed here. PROGRAM CHARACTERISTICS ..
  3. MicroRNAs in the Progression and Metastisis of Prostate Cancer
    Rajvir Dahiya; Fiscal Year: 2013
    ..In the future, these results may provide better strategies for the management of prostate cancer. ..
  4. Functional Analysis of the Embryonic Epigenome in a Non-rodent Model
    Mark E Westhusin; Fiscal Year: 2013
  5. DNA Methyltrasferase Gene Expression in Colon Cancer
    Stephen B Baylin; Fiscal Year: 2013
    ..Reactivation of these genes holds promise for constructing prevention and treatment strategies for this disease. ..
  6. Regulation of Airway Mucin Gene Expression by Epigenetic Mechanism
    Reen Wu; Fiscal Year: 2013
  7. Regional, Synpatic, Cellular Modulation of Abeta Metabolism
    David M Holtzman; Fiscal Year: 2013
    ..abstract_text> ..
    Robert S Sandler; Fiscal Year: 2013
    ..Through all of its activities, the Center improves communication, promotes collaboration, develops careers and generally enriches the intellectual climate for digestive disease research. ..