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Influence of daily social stimulation on behavioral and physiological outcomes in an animal model of PTSD.

Seetharaman S, Fleshner M, Park CR, Diamond DM - Brain Behav (2016)

Bottom Line: We also found that social stimulation and psychosocial stress produced equivalent outcomes in some measures, including adrenal and heart hypertrophy, thymus atrophy, and a reduction in poststress corticosterone levels.It is notable that daily social stimulation normalized a subset, but not all, of the PTSD-like effects.We discuss our findings in the context of the literature demonstrating that social stimulation can counteract the adverse effects of traumatic stress on behavioral and physiological measures, as well as to produce its own stress-like outcomes.

View Article: PubMed Central - PubMed

Affiliation: Department of PsychologySt. Ambrose UniversityDavenportIowa52803; Center for Preclinical and Clinical Research on PTSDUniversity of South FloridaTampaFlorida33620.

ABSTRACT

Introduction: We have shown in previous work that acute episodes of predator exposure occurring in the context of chronic social instability produced PTSD-like sequelae in rats. Our animal model of PTSD contained two components: (1) acute trauma, immobilization of rats in close proximity to a cat twice in 10 days, and (2) chronic social instability, 31 days of randomized housing of cage cohorts. Here we tested the hypothesis that daily social stimulation would block the development of the PTSD-like sequelae.

Methods: Beginning 24 h after the first cat exposure, adult male rats were given our established PTSD model, alone or in conjunction with daily social stimulation, in which all rats within a group interacted in a large apparatus for 2 h each day for the final 30 days of the PTSD regimen. All behavioral, for example, anxiety, memory, startle testing, and physiological assessments, for example, body growth, organ weights, and corticosterone levels, took place following completion of the psychosocial stress period.

Results: Daily social stimulation blocked the expression of a subset of PTSD-like effects, including predator-based cued fear conditioning, enhanced startle response, heightened anxiety on the elevated plus maze and the stress-induced suppression of growth rate. We also found that social stimulation and psychosocial stress produced equivalent outcomes in some measures, including adrenal and heart hypertrophy, thymus atrophy, and a reduction in poststress corticosterone levels.

Conclusions: Daily exposure of rats to a highly social environment blocked the development of a subset of trauma-induced sequelae, particularly fear-related outcomes. It is notable that daily social stimulation normalized a subset, but not all, of the PTSD-like effects. We discuss our findings in the context of the literature demonstrating that social stimulation can counteract the adverse effects of traumatic stress on behavioral and physiological measures, as well as to produce its own stress-like outcomes.

No MeSH data available.


Related in: MedlinePlus

Activity in the elevated plus maze (EPM). Animals in the No Social–Stress group spent significant less time in the open arms of the apparatus, indicative of heightened general anxiety, which was prevented with social stimulation (top). The No Social–Stress group spent significantly less time in the near open arms of the EPM relative to the No Social–No Stress group. This effect was prevented with social stimulation (middle left). Both Social groups spent significantly more time in the far open arms of the EPM relative to both No Social groups (middle right). Both Social groups demonstrated significantly greater movement on the EPM relative to No Social controls (lower right). Social produced significantly more head dips on the EPM compared to the No Social groups (lower right). *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social. Data are presented as mean ± SEM.
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brb3458-fig-0003: Activity in the elevated plus maze (EPM). Animals in the No Social–Stress group spent significant less time in the open arms of the apparatus, indicative of heightened general anxiety, which was prevented with social stimulation (top). The No Social–Stress group spent significantly less time in the near open arms of the EPM relative to the No Social–No Stress group. This effect was prevented with social stimulation (middle left). Both Social groups spent significantly more time in the far open arms of the EPM relative to both No Social groups (middle right). Both Social groups demonstrated significantly greater movement on the EPM relative to No Social controls (lower right). Social produced significantly more head dips on the EPM compared to the No Social groups (lower right). *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social. Data are presented as mean ± SEM.

Mentions: For EPM testing, there was a significant Stress × Social interaction, F(1, 26) = 4.21, P < 0.05. Post hoc tests showed that the Stress/No Social group spent significantly less percent of time in the open arms compared to the No Stress/No Social and Stress/Social groups, indicating that daily social stimulation prevented the stress‐induced decrease in overall time spent in the open arms of the EPM. Both groups experiencing daily social stimulation showed significantly greater percent time spent in the open arms of the apparatus relative to both No Social groups (Fig. 3, top).


Influence of daily social stimulation on behavioral and physiological outcomes in an animal model of PTSD.

Seetharaman S, Fleshner M, Park CR, Diamond DM - Brain Behav (2016)

Activity in the elevated plus maze (EPM). Animals in the No Social–Stress group spent significant less time in the open arms of the apparatus, indicative of heightened general anxiety, which was prevented with social stimulation (top). The No Social–Stress group spent significantly less time in the near open arms of the EPM relative to the No Social–No Stress group. This effect was prevented with social stimulation (middle left). Both Social groups spent significantly more time in the far open arms of the EPM relative to both No Social groups (middle right). Both Social groups demonstrated significantly greater movement on the EPM relative to No Social controls (lower right). Social produced significantly more head dips on the EPM compared to the No Social groups (lower right). *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social. Data are presented as mean ± SEM.
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brb3458-fig-0003: Activity in the elevated plus maze (EPM). Animals in the No Social–Stress group spent significant less time in the open arms of the apparatus, indicative of heightened general anxiety, which was prevented with social stimulation (top). The No Social–Stress group spent significantly less time in the near open arms of the EPM relative to the No Social–No Stress group. This effect was prevented with social stimulation (middle left). Both Social groups spent significantly more time in the far open arms of the EPM relative to both No Social groups (middle right). Both Social groups demonstrated significantly greater movement on the EPM relative to No Social controls (lower right). Social produced significantly more head dips on the EPM compared to the No Social groups (lower right). *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social. Data are presented as mean ± SEM.
Mentions: For EPM testing, there was a significant Stress × Social interaction, F(1, 26) = 4.21, P < 0.05. Post hoc tests showed that the Stress/No Social group spent significantly less percent of time in the open arms compared to the No Stress/No Social and Stress/Social groups, indicating that daily social stimulation prevented the stress‐induced decrease in overall time spent in the open arms of the EPM. Both groups experiencing daily social stimulation showed significantly greater percent time spent in the open arms of the apparatus relative to both No Social groups (Fig. 3, top).

Bottom Line: We also found that social stimulation and psychosocial stress produced equivalent outcomes in some measures, including adrenal and heart hypertrophy, thymus atrophy, and a reduction in poststress corticosterone levels.It is notable that daily social stimulation normalized a subset, but not all, of the PTSD-like effects.We discuss our findings in the context of the literature demonstrating that social stimulation can counteract the adverse effects of traumatic stress on behavioral and physiological measures, as well as to produce its own stress-like outcomes.

View Article: PubMed Central - PubMed

Affiliation: Department of PsychologySt. Ambrose UniversityDavenportIowa52803; Center for Preclinical and Clinical Research on PTSDUniversity of South FloridaTampaFlorida33620.

ABSTRACT

Introduction: We have shown in previous work that acute episodes of predator exposure occurring in the context of chronic social instability produced PTSD-like sequelae in rats. Our animal model of PTSD contained two components: (1) acute trauma, immobilization of rats in close proximity to a cat twice in 10 days, and (2) chronic social instability, 31 days of randomized housing of cage cohorts. Here we tested the hypothesis that daily social stimulation would block the development of the PTSD-like sequelae.

Methods: Beginning 24 h after the first cat exposure, adult male rats were given our established PTSD model, alone or in conjunction with daily social stimulation, in which all rats within a group interacted in a large apparatus for 2 h each day for the final 30 days of the PTSD regimen. All behavioral, for example, anxiety, memory, startle testing, and physiological assessments, for example, body growth, organ weights, and corticosterone levels, took place following completion of the psychosocial stress period.

Results: Daily social stimulation blocked the expression of a subset of PTSD-like effects, including predator-based cued fear conditioning, enhanced startle response, heightened anxiety on the elevated plus maze and the stress-induced suppression of growth rate. We also found that social stimulation and psychosocial stress produced equivalent outcomes in some measures, including adrenal and heart hypertrophy, thymus atrophy, and a reduction in poststress corticosterone levels.

Conclusions: Daily exposure of rats to a highly social environment blocked the development of a subset of trauma-induced sequelae, particularly fear-related outcomes. It is notable that daily social stimulation normalized a subset, but not all, of the PTSD-like effects. We discuss our findings in the context of the literature demonstrating that social stimulation can counteract the adverse effects of traumatic stress on behavioral and physiological measures, as well as to produce its own stress-like outcomes.

No MeSH data available.


Related in: MedlinePlus