Uncontrollable Stress Exposure
Objective: To examine the effects of brief exposure to uncontrollable stress on fear conditioning, fear extinction, and dendritic morphology of pyramidal neurons in the infralimbic and prelimbic regions of the medial prefrontal cortex in mice
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Equipment1
Not specified • Not specified • Not specified • Not specified
Materials1
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Protocol Steps
Swim stress exposure
Mice are exposed to episodes of swim stress as an uncontrollable stressor
Note: Three episodes of stress were administered, with the final exposure occurring 24 hours before fear conditioning
View evidence from paper
“Exposure to three episodes of stress ending 24 h before fear conditioning significantly attenuated the rate of cued fear extinction”
Timing of stress exposure relative to fear conditioning
The final swim stress episode is timed to end 24 hours before fear conditioning begins
Note: This timing is critical for the experimental design
View evidence from paper
“Exposure to three episodes of stress ending 24 h before fear conditioning significantly attenuated the rate of cued fear extinction”
Fear conditioning
Mice undergo fear conditioning after the stress exposure period
Note: Fear conditioning was not affected by prior stress exposure
View evidence from paper
“did not affect fear conditioning or cue or context recall”
Fear extinction
Repeated presentation of conditioned stimulus in the absence of unconditioned aversive stimulus
Note: Stress-exposed mice showed significantly attenuated rate of cued fear extinction compared to nonstressed controls
View evidence from paper
“Extinction of conditioned fear responses is an active learning process resulting from the repeated presentation of a conditioned stimulus in the absence of the unconditioned aversive stimulus”
Neuronal analysis
Analysis of dendritic morphology of pyramidal neurons in infralimbic and prelimbic regions using Golgi staining
Note: One or three exposures to daily swim stress caused significant retraction of terminal branches of apical dendrites in IL neurons but not basilar dendrites or PL neurons
View evidence from paper
“one or three exposures to daily swim stress caused significant retraction of terminal branches of apical, but not basilar, dendrites of IL neurons”