Chronic psychosocial stress impairs learning and memory and increases sensitivity to yohimbine in adult rats.
BACKGROUND
It is well known that intense and prolonged stress can produce cognitive impairments and hippocampal damage and increase noradrenergic activity in humans. This study investigated the hypothesis that chronic psychosocial stress would affect behavior, drug sensitivity, and hippocampal-dependent learning and memory in rats. The work provides a novel connection between animal and human studies by evaluating the effects of stress on a rat's response to yohimbine, an alpha(2) adrenergic receptor antagonist.


METHODS
Rats were exposed to a cat for 5 weeks and randomly housed with a different group of cohorts each day (psychosocial stress). The effects of the stress manipulations were then assessed on open field behavior, spatial learning and memory in the radial arm water maze and the behavioral response to a low dose of yohimbine (1.5 mg/kg).


RESULTS
Stressed rats displayed impaired habituation to a novel environment, heightened anxiety, and increased sensitivity to yohimbine. In addition, the stressed rats exhibited impaired learning and memory.


CONCLUSIONS
There are commonalities between the current findings on stressed rats and from studies on traumatized people. Thus, psychosocial stress manipulations in rats may yield insight into the basis of cognitive and neuroendocrine disturbances that commonly occur in people with anxiety disorders.
Park
C R
CR
Department of Psychology, University of South Florida, 4202 E. Fowler Ave., Tampa, FL 33620, USA.
Campbell
A M
AM
Diamond
D M
DM
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001008:Anxiety Disorders; D001522:Behavior, Animal / Q000187:drug effects; D002908:Chronic Disease; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000187:drug effects; D006185:Habituation, Psychophysiologic / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological; D015016:Yohimbine / Q000008:administration & dosage / Q000494:pharmacology*
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D015016:Yohimbine