Prior treadmill exercise promotes resilience to vicarious trauma in rats

Abstract

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.

Chronic social defeat stress mouse model: Current view on its behavioral deficits and modifications.

“…Besides, various social defeat stress rat models have been developed in recent years, including the CSDS and psychosocial witness stress rat model (Patki, Solanki, & Salim, 2014). Existing studies have shown that behavioral and physiologic characteristics of these rat models are similar to those in mouse models (Arora et al, 2018;Finnell et al, 2018;Giacobbo et al, 2020;Kochi et al, 2017;Morais-Silva et al, 2019;Zaidi et al, 2020), which further confirms the feasibility of CSDS-induced behavioral deficits among different strains.…”

Early Life Sleep Deprivation: Role of Oxido-Inflammatory Processes

“…LD test detects anxiety indicated by avoidance of lit areas, but EPM test detects anxiety-like behavior that results from avoidance of open, lit and elevated areas. Thus, while rats at PND60 did not exhibit anxiety-like behavior in LD test, which is a mild test (Salim et al, 2010), anxiety-like phenotype was evident in a more stringent EPM test (Kochi et al, 2017). Additionally, SD did not impact the high sociability behavior in rats (Figure 5).…”

Mice Cohabiting With Familiar Conspecific in Chronic Stress Condition Exhibit Methamphetamine-Induced Locomotor Sensitization and Augmented Consolation Behavior

“…For instance, studies have reported that mice or rats observing traumatic events, in this case conspecifics subjected to repeated social defeat, elicited enhanced avoidance of open arms ( Sial et al, 2016 ; Kochi et al, 2017 ), affecting ( Patki et al, 2014 , 2015 ), or not ( Warren et al, 2013 ), the general locomotor activity in the open field. Additionally, Miao et al (2018) found decreased exploratory activity of spectator pregnant mice in the open arms after successive exposure to mate social defeat.…”