TY - JOUR
T1 - Chronic stress, cyclic 17β-estradiol, and daily handling influences on fear conditioning in the female rat
AU - Hoffman, A. N.
AU - Armstrong, Charles E.
AU - Hanna, Jeffery J.
AU - Conrad, Cheryl
N1 - Funding Information:
Supported by funds from the Arizona Biomedical Research Commission (Conrad), the ASU School of Life Sciences and the Howard Hughes Medical Institute through the Undergraduate Science Education Program (Armstrong and Hanna). We gratefully acknowledge the following individuals: Dr. Federico Sanabria, Dr. Heather Bimonte-Nelson, Renée Dille, Thu Huynh, Anthony Tran, Collin Nelson, Natalie Conboy, Bryce Ortiz, Agnieszka Mika and Mariam El-Ashmawy.
Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2010/10
Y1 - 2010/10
N2 - 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 1. h 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.
AB - 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 1. h 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.
KW - Amygdala
KW - Chronic stress
KW - Estrogen
KW - Extinction
KW - Fear conditioning
KW - Handling
KW - Ovariectomy
KW - Restraint
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U2 - 10.1016/j.nlm.2010.08.010
DO - 10.1016/j.nlm.2010.08.010
M3 - Article
C2 - 20807583
AN - SCOPUS:77957233577
SN - 1074-7427
VL - 94
SP - 422
EP - 433
JO - Neurobiology of Learning and Memory
JF - Neurobiology of Learning and Memory
IS - 3
ER -