Document Detail

Differential effects of ovarian steroids on anxiety versus fear as measured by open field test and fear-potentiated startle.
MedLine Citation:
PMID:  16154649     Owner:  NLM     Status:  MEDLINE    
The ovarian steroids, estrogen (E) and progesterone (P), have been shown to affect anxiety and fear in humans and animals, although with inconsistent results. These ambiguous findings may be due to differential actions of ovarian steroids on anxiety versus fear. To investigate such a role, we used the open field test (OFT) and fear-potentiated startle (FPS). We examined these behaviors between cycling female rats in proestrus (high E and rising P) or diestrus (low E and P), as well as between ovariectomized rats treated for 2 weeks with placebo, E, or E plus P (OVX, OVX/E, OVX/EP, respectively). We found no differences in anxiety-like or fear behaviors in OFT or FPS between proestrus and diestrus rats, perhaps due to the opposing effects of E and P. In contrast, we found that the OVX/E rats spent more time in the center of the OFT compared to the OVX and OVX/EP rats with no difference in overall activity level, suggesting that E reduced anxiety and this was opposed by P. With FPS, the OVX/E rats showed increased startle in the first third of the testing session, followed by a rapid decline in startle magnitude in subsequent trials. The addition of P to E treatment counteracted this effect. In conclusion, E may have differential effects on specific components of anxiety and fear; E may decrease anxiety in a naturalistic environment, but intensify both fear learning and extinction processes. P antagonizes these E effects on anxiety and fear.
Ryoko Hiroi; John F Neumaier
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2005-09-09
Journal Detail:
Title:  Behavioural brain research     Volume:  166     ISSN:  0166-4328     ISO Abbreviation:  Behav. Brain Res.     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2005-11-28     Completed Date:  2006-03-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8004872     Medline TA:  Behav Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  93-100     Citation Subset:  IM    
Department of Psychology, University of Washington, Seattle, WA 98195, USA.
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MeSH Terms
Analysis of Variance
Anxiety / drug therapy*
Behavior, Animal
Conditioning (Psychology) / drug effects
Drug Delivery Systems / methods
Estrogens / administration & dosage*,  blood
Estrous Cycle
Exploratory Behavior / drug effects
Fear / drug effects*
Ovariectomy / methods
Pain Measurement / methods
Progesterone / administration & dosage*,  blood
Radioimmunoassay / methods
Rats, Sprague-Dawley
Startle Reaction / drug effects*
Vaginal Smears / methods
Reg. No./Substance:
0/Estrogens; 57-83-0/Progesterone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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