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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

Influence of psychosocial stress on growth rate and organ weights. Psychosocial stress produced a significant decrease in growth rate. This effect was prevented in the Stress/Social group. Data are shown as mean g/day (upper left). Mean thymus gland weight was significantly lower in both Social groups and Stress/No Social relative to the No Social/No Stress group (upper right). Social stimulation produced a significant increase in mean heart weight relative to home cage controls (lower left). Both Social groups and No Social/Stress groups demonstrated robust increase in mean adrenal weight relative to home cage controls (lower right). Organ weights are shown as mean mg/100 g body weight. *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social.
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brb3458-fig-0006: Influence of psychosocial stress on growth rate and organ weights. Psychosocial stress produced a significant decrease in growth rate. This effect was prevented in the Stress/Social group. Data are shown as mean g/day (upper left). Mean thymus gland weight was significantly lower in both Social groups and Stress/No Social relative to the No Social/No Stress group (upper right). Social stimulation produced a significant increase in mean heart weight relative to home cage controls (lower left). Both Social groups and No Social/Stress groups demonstrated robust increase in mean adrenal weight relative to home cage controls (lower right). Organ weights are shown as mean mg/100 g body weight. *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social.

Mentions: Growth rates were based on the increase in weight during the course of the 31‐day period of psychosocial stress. There was a significant Stress × Social stimulation interaction, F(1, 33) = 9.45, P < 0.05. Post hoc tests showed a significantly reduced growth rate of the Stress/No Social group compared to No Stress/No Social and No Stress/Social groups (Fig. 6, upper left). The thymus gland exhibited the inverse effect of the adrenal gland in that there were significant main effects of Stress, F(1, 28) = 5.96, and social stimulation, F(1, 28) = 7.54 (Ps < 0.05), and all three groups with Stress and/or Social factors produced a smaller thymus gland compared to the No Stress/No Social group (Fig. 6, upper right). There was a significant main effect of social stimulation for the heart weight, F(1, 32) = 4.79, P < 0.05, and both Social groups exhibited greater heart weights than the No Social/No Stress group (Fig. 6, lower right). Analysis of adrenal weights revealed a significant main effect of social stimulation, F(1, 31) = 5.95, P < 0.05, indicating that social stimulation produced significantly heavier adrenal glands than the no social manipulations. Post hoc tests showed that both social stimulation groups and the No Social/Stress group had significantly heavier adrenal glands compared to the No Social/No Stress group (Fig. 6, lower right). There were no significant effects of psychosocial stress or social stimulation on heart rate or blood pressure (data not shown).


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)

Influence of psychosocial stress on growth rate and organ weights. Psychosocial stress produced a significant decrease in growth rate. This effect was prevented in the Stress/Social group. Data are shown as mean g/day (upper left). Mean thymus gland weight was significantly lower in both Social groups and Stress/No Social relative to the No Social/No Stress group (upper right). Social stimulation produced a significant increase in mean heart weight relative to home cage controls (lower left). Both Social groups and No Social/Stress groups demonstrated robust increase in mean adrenal weight relative to home cage controls (lower right). Organ weights are shown as mean mg/100 g body weight. *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834360&req=5

brb3458-fig-0006: Influence of psychosocial stress on growth rate and organ weights. Psychosocial stress produced a significant decrease in growth rate. This effect was prevented in the Stress/Social group. Data are shown as mean g/day (upper left). Mean thymus gland weight was significantly lower in both Social groups and Stress/No Social relative to the No Social/No Stress group (upper right). Social stimulation produced a significant increase in mean heart weight relative to home cage controls (lower left). Both Social groups and No Social/Stress groups demonstrated robust increase in mean adrenal weight relative to home cage controls (lower right). Organ weights are shown as mean mg/100 g body weight. *P < 0.05 relative to No Social/No Stress. #P < 0.05 relative to Stress/No Social.
Mentions: Growth rates were based on the increase in weight during the course of the 31‐day period of psychosocial stress. There was a significant Stress × Social stimulation interaction, F(1, 33) = 9.45, P < 0.05. Post hoc tests showed a significantly reduced growth rate of the Stress/No Social group compared to No Stress/No Social and No Stress/Social groups (Fig. 6, upper left). The thymus gland exhibited the inverse effect of the adrenal gland in that there were significant main effects of Stress, F(1, 28) = 5.96, and social stimulation, F(1, 28) = 7.54 (Ps < 0.05), and all three groups with Stress and/or Social factors produced a smaller thymus gland compared to the No Stress/No Social group (Fig. 6, upper right). There was a significant main effect of social stimulation for the heart weight, F(1, 32) = 4.79, P < 0.05, and both Social groups exhibited greater heart weights than the No Social/No Stress group (Fig. 6, lower right). Analysis of adrenal weights revealed a significant main effect of social stimulation, F(1, 31) = 5.95, P < 0.05, indicating that social stimulation produced significantly heavier adrenal glands than the no social manipulations. Post hoc tests showed that both social stimulation groups and the No Social/Stress group had significantly heavier adrenal glands compared to the No Social/No Stress group (Fig. 6, lower right). There were no significant effects of psychosocial stress or social stimulation on heart rate or blood pressure (data not shown).

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