Document Detail

Chronic stress, cyclic 17β-estradiol, and daily handling influences on fear conditioning in the female rat.
MedLine Citation:
PMID:  20807583     Owner:  NLM     Status:  MEDLINE    
Chronic stress and estrogens alter many forebrain regions in female rats that affect cognition. In order to investigate how chronic stress and estrogens influence fear learning and memory, we ovariectomized (OVX) female Sprague-Dawley rats and repeatedly injected them (s.c.) with 17β-estradiol (E, 10 μg/250 g or sesame oil vehicle, VEH). Concurrently, rats were restrained for 6 h/d/21 d (STR) or left undisturbed (CON). Rats were then fear conditioned with 4 tone-footshock pairings and then after 1 h and 24 h delays, given 15 tone extinction trials. Regardless of E treatment, chronic stress (VEH, E) facilitated freezing to tone during acquisition and extinction following a 1h delay, but not during extinction after a 24 h delay. E did not influence freezing to tone during any phase of fear conditioning for either the control or chronically stressed rats, but did influence contextual conditioning that may have been carried predominately by the STR group. In the second experiment, we investigated "handling" influences on fear conditioning acquisition, given the disparate findings from the current study and previous work (Baran, Armstrong, Niren, & Conrad, 2010; Baran, Armstrong, Niren, Hanna, & Conrad, 2009). Female rats remained gonadally-intact since E did not influence tone fear conditioning. Indeed, brief daily handling (1-3 m/d/21 d) facilitated acquisition of fear conditioning in chronically stressed female rats, and either had no effect or slightly attenuated fear conditioning in controls. Thus, chronic stress impacts amygdala-mediated fear learning in both OVX- and gonadally-intact females as found previously in males, with handling significantly influencing these outcomes.
Ann N Hoffman; Charles E Armstrong; Jeffery J Hanna; Cheryl D Conrad
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-08-31
Journal Detail:
Title:  Neurobiology of learning and memory     Volume:  94     ISSN:  1095-9564     ISO Abbreviation:  Neurobiol Learn Mem     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-04     Completed Date:  2011-01-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9508166     Medline TA:  Neurobiol Learn Mem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  422-33     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier Inc. All rights reserved.
Department of Psychology, Arizona State University, Box 1104, Tempe, AZ 85287-1104, USA.
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MeSH Terms
Analysis of Variance
Association Learning / drug effects,  physiology*
Conditioning, Classical / drug effects,  physiology*
Estradiol / administration & dosage*
Extinction, Psychological / drug effects,  physiology
Fear / drug effects,  physiology*
Freezing Reaction, Cataleptic / drug effects,  physiology*
Rats, Sprague-Dawley
Restraint, Physical
Stress, Physiological / physiology*
Reg. No./Substance:

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