Genetic Markers for PTSD Risk and Resilience Among Survivors of the World Trade Center Attacks

Although early-life stress is a significant risk factor for developing anxiety disorders, including posttraumatic stress disorder (PTSD), the underlying mechanisms are unclear. Corticotropin releasing hormone (CRH) is disrupted in individuals with PTSD and early-life stress and hence may mediate the effects of early-life stress on PTSD risk. We hypothesized that CRH hyper-signaling in the forebrain during early development is sufficient to increase response to trauma in adulthood. To test this hypothesis, we induced transient, forebrain-specific, CRH overexpression during early-life (pre-puberty, CRHOE dev ) in double-mutant mice (Camk2a-rtta2 × tetO-Crh) and tested their behavioral and gene expression responses to the predator stress model of PTSD in adulthood. In one cohort of CRHOE dev exposed and unexposed mice, avoidance and arousal behaviors were examined 7-15 days after exposure to predator stress. In another cohort, gene expression changes in Crhr1, Crhr2, and Fkbp51 in forebrain of CRHOE dev exposed and unexposed mice were examined 7 days after predator stress. CRHOE dev induced robust increases in startle reactivity and reductions in startle inhibition independently of predator stress in both male and female mice. Avoidance behaviors after predator stress were highly dependent on sex and CRHOE dev exposure. Whereas stressed females exhibited robust avoidance responses that were not altered by CRHOE dev , males developed significant avoidance only when exposed to both CRHOE dev and stress. Quantitative real-time-PCR analysis indicated that CRHOE dev unexposed males exhibit significant changes in Crhr2 expression in the amygdala and bed nucleus stria terminalis in response to stress, whereas males exposed to CRHOE dev did not. Similar to CRHOE dev males, females exhibited no significant Crhr2 gene expression changes in response to stress. Cortical Fkbp51 expression was also significantly reduced by stress and CRHOE dev exposure in males, but not in females. These findings indicate that forebrain CRH hyper-signaling in early-life is sufficient to increase enduring effects of adult trauma and attenuate Crhr2 expression changes in response to stress in males. These data support growing evidence for significant sex differences in response to trauma, and support further study of CRHR2 as a candidate mechanism for PTSD risk.

Section: Discussionsupporting

confidence: 74%

Overexpression of Forebrain CRH During Early Life Increases Trauma Susceptibility in Adulthood

Tóth

Flandreau

Deslauriers

et al. 2015

“…These include polymorphisms or expression of BDNF (Krishnan et al, 2007), GABRA2 (Nelson et al, 2009), 5-HT1A receptors, dopamine or serotonin transporters (Segman et al, 2002;Kilpatrick et al, 2007;Stein et al, 2009;Wald et al, 2013), catechol-O-methyl transferase (COMT; Jabbi et al, 2007;Kolassa et al, 2010), glucocorticoid receptors and factors that modulate them such as FK506-binding protein (FKBP5;Binder et al, 2008;Derijk and de Kloet, 2008;McGowan et al, 2009;Sarapas et al, 2011), and methylation of corticotrophin-releasing factor (CRF) receptor DNA (Elliott et al, 2010). Several genetically distinct rodent lines are differentially resistant/vulnerable to the effects of stress (Razzoli et al, 2011;Savignac et al, 2011;Camp et al, 2012;Fuchsl et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

Hetzel

Rosenkranz

2014

Severe and repeated stress has damaging effects on health, including initiation of depression and anxiety. Stress that occurs during development has long-lasting and particularly damaging effects on emotion. The basolateral amygdala (BLA) plays a key role in many affective behaviors, and repeated stress causes different forms of BLA hyperactivity in adolescent and adult rats. However, the mechanism is not known. Furthermore, not every individual is susceptible to the negative consequences of stress. Differences in the effects of stress on the BLA might contribute to determine whether an individual will be vulnerable or resilient to the effects of stress on emotion. The purpose of this study is to test the cellular underpinnings for age dependency of BLA hyperactivity after stress, and whether protective changes occur in resilient individuals. To test this, the effects of repeated stress on membrane excitability and other membrane properties of BLA principal neurons were compared between adult and adolescent rats, and between vulnerable and resilient rats, using in vitro whole-cell recordings. Vulnerability was defined by adrenal gland weight, and verified by body weight gain after repeated restraint stress, and fecal pellet production during repeated restraint sessions. We found that repeated stress increased the excitability of BLA neurons, but in a manner that depended on age and BLA subnucleus. Furthermore, stress resilience was associated with an opposite pattern of change, with increased slow afterhyperpolarization (AHP) potential, whereas vulnerability was associated with decreased medium AHP. The opposite outcomes in these two populations were further distinguished by differences of anxiety-like behavior in the elevated plus maze that were correlated with BLA neuronal excitability and AHP. These results demonstrate a substrate for BLA hyperactivity after repeated stress, with distinct membrane properties to target, as well as age-dependent factors that contribute to resilience to the effects of stress.

“…Alterations in the transcriptional patterns of expression for genes involved in inflammatory pathways have also been associated with PTSD (Segman et al, 2005;Yehuda et al, 2009;Zieker et al, 2007). Nuclear factor-κB (NFκB), signal transducer and activator of transcription 5B, and nuclear factor I/A are all critical transcription factors with substantive roles in the activation of cytokine responses to challenge whose activity is increased in the presence of PTSD (Guardado et al, 2016;O'Donovan et al, 2011;Pace et al, 2012;Sarapas et al, 2011). Gene expression of the proinflammatory cytokine IL-18 and its receptor IL-18R1 is decreased in individuals with PTSD (Mehta et al, 2011;Segman et al, 2005;Zieker et al, 2007).…”

Section: Ptsd and Inflammationmentioning

confidence: 99%

Inflammation in Fear- and Anxiety-Based Disorders: PTSD, GAD, and Beyond

Michopoulos

Powers

Gillespie

et al. 2016

544

376

The study of inflammation in fear-and anxiety-based disorders has gained interest as growing literature indicates that proinflammatory markers can directly modulate affective behavior. Indeed, heightened concentrations of inflammatory signals, including cytokines and C-reactive protein, have been described in posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), and phobias (agoraphobia, social phobia, etc.). However, not all reports indicate a positive association between inflammation and fear-and anxiety-based symptoms, suggesting that other factors are important in future assessments of inflammation's role in the maintenance of these disorders (ie, sex, co-morbid conditions, types of trauma exposure, and behavioral sources of inflammation). The most parsimonious explanation of increased inflammation in PTSD, GAD, PD, and phobias is via the activation of the stress response and central and peripheral immune cells to release cytokines. Dysregulation of the stress axis in the face of increased sympathetic tone and decreased parasympathetic activity characteristic of anxiety disorders could further augment inflammation and contribute to increased symptoms by having direct effects on brain regions critical for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Taken together, the available data suggest that targeting inflammation may serve as a potential therapeutic target for treating these fear-and anxiety-based disorders in the future. However, the field must continue to characterize the specific role pro-inflammatory signaling in the maintenance of these unique psychiatric conditions.