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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

Serum levels of CORT under baseline, stress, and poststress conditions. There were no significant between‐group differences in CORT measures at baseline or after a 20‐min restraint stress period. At the 60‐min postrestraint time point, the No Social/Stress group exhibited significantly lower CORT levels than all three other groups. Data are shown as mean CORT (μg/dL) ± SEM. *P < 0.05 relative to No Social/No PTSD.
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brb3458-fig-0005: Serum levels of CORT under baseline, stress, and poststress conditions. There were no significant between‐group differences in CORT measures at baseline or after a 20‐min restraint stress period. At the 60‐min postrestraint time point, the No Social/Stress group exhibited significantly lower CORT levels than all three other groups. Data are shown as mean CORT (μg/dL) ± SEM. *P < 0.05 relative to No Social/No PTSD.

Mentions: Analysis of serum CORT levels revealed no significant main effects or interactions at any of the time points. Planned comparisons based on prior findings of enhanced negative feedback of animals housed under enriched environments (Mohammed et al. 1993) and in PTSD patients (Yehuda et al. 1995a), revealed that the control (No Stress/No Social) group exhibited significantly greater CORT levels at the 80 min time point relative to all three groups with Stress and/or Social stimulation manipulations (Fig. 5), t(14) = 2.70, social stimulation–no psychosocial stress, t(14) = 2.75, and social stimulation–psychosocial stress, t(13) = 2.65, P values < 0.05.


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)

Serum levels of CORT under baseline, stress, and poststress conditions. There were no significant between‐group differences in CORT measures at baseline or after a 20‐min restraint stress period. At the 60‐min postrestraint time point, the No Social/Stress group exhibited significantly lower CORT levels than all three other groups. Data are shown as mean CORT (μg/dL) ± SEM. *P < 0.05 relative to No Social/No PTSD.
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getmorefigures.php?uid=PMC4834360&req=5

brb3458-fig-0005: Serum levels of CORT under baseline, stress, and poststress conditions. There were no significant between‐group differences in CORT measures at baseline or after a 20‐min restraint stress period. At the 60‐min postrestraint time point, the No Social/Stress group exhibited significantly lower CORT levels than all three other groups. Data are shown as mean CORT (μg/dL) ± SEM. *P < 0.05 relative to No Social/No PTSD.
Mentions: Analysis of serum CORT levels revealed no significant main effects or interactions at any of the time points. Planned comparisons based on prior findings of enhanced negative feedback of animals housed under enriched environments (Mohammed et al. 1993) and in PTSD patients (Yehuda et al. 1995a), revealed that the control (No Stress/No Social) group exhibited significantly greater CORT levels at the 80 min time point relative to all three groups with Stress and/or Social stimulation manipulations (Fig. 5), t(14) = 2.70, social stimulation–no psychosocial stress, t(14) = 2.75, and social stimulation–psychosocial stress, t(13) = 2.65, P values < 0.05.

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