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Repeated exposure to conditioned fear stress increases anxiety and delays sleep recovery following exposure to an acute traumatic stressor.

Greenwood BN, Thompson RS, Opp MR, Fleshner M - Front Psychiatry (2014)

Bottom Line: The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress.This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior.These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Colorado Denver , Denver, CO , USA.

ABSTRACT
Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by human beings, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to no, mild (10), or severe (100) acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced rapid eye movement (REM) and non-REM (NREM) sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

No MeSH data available.


Related in: MedlinePlus

Time lines depicting the series of events used. in Experiment 1 (A), Experiment 2 (B), and Experiment 3 (C).
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Figure 1: Time lines depicting the series of events used. in Experiment 1 (A), Experiment 2 (B), and Experiment 3 (C).

Mentions: Experiment 1 was designed to test the hypothesis that prior repeated fear stress sensitizes anxiety responses to novel acute stressor exposure. Rats were randomly assigned to the following groups: no repeated fear (home cage)/0 tail shocks (n = 7); home cage/10 tail shocks (n = 8); home cage/100 tail shocks (n = 8); repeated fear/0 tail shocks (n = 8); repeated fear/10 tail shocks (n = 8); repeated fear/100 tail shocks (n = 7). All rats were tested for anxiety-like behavior using social exploration and shock-elicited freezing 24 h following tail shock exposure. Figure 1A shows the sequence of events followed during Experiment 1.


Repeated exposure to conditioned fear stress increases anxiety and delays sleep recovery following exposure to an acute traumatic stressor.

Greenwood BN, Thompson RS, Opp MR, Fleshner M - Front Psychiatry (2014)

Time lines depicting the series of events used. in Experiment 1 (A), Experiment 2 (B), and Experiment 3 (C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4202708&req=5

Figure 1: Time lines depicting the series of events used. in Experiment 1 (A), Experiment 2 (B), and Experiment 3 (C).
Mentions: Experiment 1 was designed to test the hypothesis that prior repeated fear stress sensitizes anxiety responses to novel acute stressor exposure. Rats were randomly assigned to the following groups: no repeated fear (home cage)/0 tail shocks (n = 7); home cage/10 tail shocks (n = 8); home cage/100 tail shocks (n = 8); repeated fear/0 tail shocks (n = 8); repeated fear/10 tail shocks (n = 8); repeated fear/100 tail shocks (n = 7). All rats were tested for anxiety-like behavior using social exploration and shock-elicited freezing 24 h following tail shock exposure. Figure 1A shows the sequence of events followed during Experiment 1.

Bottom Line: The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress.This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior.These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Colorado Denver , Denver, CO , USA.

ABSTRACT
Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by human beings, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to no, mild (10), or severe (100) acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced rapid eye movement (REM) and non-REM (NREM) sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep/wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep/wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

No MeSH data available.


Related in: MedlinePlus