Witnessing traumatic events and post-traumatic stress disorder: Insights from an animal model

Patki, Gaurav; Salvi, Ankita; Liu, Hesong; Salim, Samina

doi:10.1016/j.neulet.2015.05.060

Cited by 34 publications

(38 citation statements)

References 22 publications

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“…3), a sign of increased depression-like behavior [17, 26]. EX-TW rats spent less time, 18.21 ± 2.69 seconds, in the immobile position when compared to TW or SD groups (TW: 39.50 ± 8.08 seconds, SD: 39.25 ± 4.85 seconds).…”

Section: Resultsmentioning

confidence: 99%

“…The time spent immobile by EX-TW rats was comparable to CON and EX groups (CON: 15.50 ± 3.91 seconds, EX: 14.64 ± 2.49 seconds). Furthermore, EX-TW rats spent significantly less time immobile than SD (53.61%, p<0.05) or TW (53.90%, p<0.05) rats, a behavior suggestive of a reduced despair-like behavior [17, 26]. In the FST, assessing depression-like behavior, both SD and TW rats presented high depression-like behavior.…”

Section: Resultsmentioning

confidence: 99%

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Prior treadmill exercise promotes resilience to vicarious trauma in rats

Kochi

Liu

Zaidi

et al. 2017

Progress in Neuro-Psychopharmacology and Biological Psychiatry

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Background Post-traumatic stress disorder (PTSD) is a serious psychological condition, which can develop both from physically experiencing and also from witnessing traumatic events. There is evidence that physical exercise can have a positive impact on the symptoms of PTSD. Relevant to this, in our previous pre-clinical work, beneficial effects of treadmill exercise were reported on PTSD-like behaviors in a social defeat paradigm, a rat model of direct physical trauma. However, the role of exercise on vicariously acquired PTSD-like phenotype was not examined. Objective In this study, we utilized a rodent PTSD model, which mimics both the physical as well as the witness experience of trauma, and examined the impact of moderate treadmill exercise in mitigating vicariously acquired PTSD-like behaviors in rats. Methods Our PTSD model is a modified social defeat paradigm, which involves aggressive encounters between a large Long-Evans male rat (resident) and a smaller Sprague-Dawley male rat (intruder), resulting in intruder social defeat. The cage mate of the intruder is positioned to witness intruder defeat. Rats were grouped as control (CON), social defeat (SD), exercise (EX), trauma witness (TW), and exercise prior to trauma witness (EX-TW). After acclimatization for 7 days, the exercised groups were subjected to a daily 30-min treadmill exercise regimen for 14 days. On day 21, the SD group was exposed for 7 days of social defeat, while the TW groups witnessed social defeat. On days 28–34, behavioral and cognitive tests including short-term (STM) and long-term (LTM) memory function, anxiety- and depression-like behaviors were conducted. Results TW and SD rats demonstrated the highest levels of anxiety- and depression-like behaviors, while EX-TW rats did not exhibit anxiety- and depression-like behaviors. TW and SD rats showed no impairments in STM. However, TW and SD rats showed impairments in LTM, and exercise rescued LTM impairments in EX-TW rats. Conclusions This study demonstrates that rats subjected to direct experience or witness of social defeat exhibited PTSD-like behaviors, while moderate treadmill exercise prevented trauma witness-induced behavioral impairments. These studies have important translational value suggesting that prior treadmill exercise might provide resilience to stressful stimuli and perhaps mitigate the witnessing effects of traumatic events.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Prior treadmill exercise promotes resilience to vicarious trauma in rats

Kochi

Liu

Zaidi

et al. 2017

Progress in Neuro-Psychopharmacology and Biological Psychiatry

Self Cite

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“…More recently, witness models have emerged that consist of a male observing the resident-intruder model of social defeat stress, thereby allowing for a comparison between physical and psychological exposure to social stress [ 29 – 33 ]. Social defeat stress not only has ethological relevance, as rodents (rats, mice, and prairie voles) naturally exist in a social hierarchy, but also provides face validity to stressors capable of inducing a depressive-like state [ 14 , 34 – 38 ].…”

Section: Introductionmentioning

confidence: 99%

Physical versus psychological social stress in male rats reveals distinct cardiovascular, inflammatory and behavioral consequences

et al. 2017

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Repeated exposure to social stress can precipitate the development of psychosocial disorders including depression and comorbid cardiovascular disease. While a major component of social stress often encompasses physical interactions, purely psychological stressors (i.e. witnessing a traumatic event) also fall under the scope of social stress. The current study determined whether the acute stress response and susceptibility to stress-related consequences differed based on whether the stressor consisted of physical versus purely psychological social stress. Using a modified resident-intruder paradigm, male rats were either directly exposed to repeated social defeat stress (intruder) or witnessed a male rat being defeated. Cardiovascular parameters, behavioral anhedonia, and inflammatory cytokines in plasma and the stress-sensitive locus coeruleus were compared between intruder, witness, and control rats. Surprisingly intruders and witnesses exhibited nearly identical increases in mean arterial pressure and heart rate during acute and repeated stress exposures, yet only intruders exhibited stress-induced arrhythmias. Furthermore, re-exposure to the stress environment in the absence of the resident produced robust pressor and tachycardic responses in both stress conditions indicating the robust and enduring nature of social stress. In contrast, the long-term consequences of these stressors were distinct. Intruders were characterized by enhanced inflammatory sensitivity in plasma, while witnesses were characterized by the emergence of depressive-like anhedonia, transient increases in systolic blood pressure and plasma levels of tissue inhibitor of metalloproteinase. The current study highlights that while the acute cardiovascular responses to stress were identical between intruders and witnesses, these stressors produced distinct differences in the enduring consequences to stress, suggesting that witness stress may be more likely to produce long-term cardiovascular dysfunction and comorbid behavioral anhedonia while exposure to physical stressors may bias the system towards sensitivity to inflammatory disorders.

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“…Social stress is a widespread environmental factor that can affect health and research has shown that experiencing or witnessing traumatic events can increase the risk of anxiety, depression and PTSD (Patki et al, 2015). In the traditional rodent models of physical social stress, the subordination of one male by a larger and more aggressive male simulates a socially-induced psychological stressor and leads to depression and anxiety-like behaviors (Golden et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Voiding Behavior and Efferent Bladder Function Altered in Mice Following Social Defeat but Not Witness Trauma

et al. 2020

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Psychological stress is associated with bladder dysfunction, however, the local bladder mechanisms affected are not well understood. This study aimed to determine how psychological stress, caused by social defeat or witness trauma, affects voiding behavior and bladder function. Pairs of male C57Bl/6J mice were placed in a custom-made plexiglass chamber with an aggressor ARC(S) mouse for 1 h/day for 10 days. The social defeat mouse was in physical contact with the aggressor, while the witness was physically separated but could observe interactions between its cage-mate and the aggressor. Age matched control pairs were used for comparison. Voiding analysis was conducted periodically over the 10 days. An ex vivo whole bladder preparation was used to assess functional changes after the period of stress. Plasma corticosterone levels were significantly increased by both social defeat and witness trauma stress when compared to unstressed controls. Voiding analysis revealed a significant decrease in voiding frequency in the social defeat group compared to control animals, indicating an altered voiding phenotype. Witness trauma did not alter voiding behavior. Bladder contractile responses to cholinergic stimulation were not significantly altered in either stress group, nor was relaxation to the beta-adrenoceptor agonist isoprenaline. However, nerve evoked contractile responses were significantly increased at all frequencies in bladders from social defeat but not witness trauma mice. Purinergic contractile responses were also significantly enhanced in this group. Social defeat also resulted in increased urothelial acetylcholine release during bladder distension, with no change in ATP release. In conclusion, functional bladder changes are dependent upon stressor type. Enhanced urothelial acetylcholine may desensitize bladder sensory nerves, which, coupled with more efficient voiding contractions due to enhanced nervemediated and purinergic detrusor responses, may account for the altered voiding phenotype observed. This study reports a male model of social defeat stress with reduced urinary frequency, with no voiding changes observed in the witness.

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Witnessing traumatic events and post-traumatic stress disorder: Insights from an animal model

Cited by 34 publications

References 22 publications

Prior treadmill exercise promotes resilience to vicarious trauma in rats

Prior treadmill exercise promotes resilience to vicarious trauma in rats

Physical versus psychological social stress in male rats reveals distinct cardiovascular, inflammatory and behavioral consequences

Voiding Behavior and Efferent Bladder Function Altered in Mice Following Social Defeat but Not Witness Trauma

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