Document Detail

Pregnancy is associated with low fear reactions in ewes.
MedLine Citation:
PMID:  11282143     Owner:  NLM     Status:  MEDLINE    
The aims of the study were: (1) to test the influence of pregnancy on responses of ewes to several fear-eliciting situations, (2) to compare the first and latest stages of pregnancy, and (3) to investigate possible correlations between fear reactions and progesterone levels. Fear reactions of nonpregnant (NP; N=22) and pregnant (P) Ile-de-France ewes (day 40 of pregnancy: N=43; day 140 of pregnancy: N=19) were compared during three situations classically reported to induce fear in sheep: isolation, surprise, and the presence of a human. P ewes displayed significantly lower fear reactions than NP ewes when isolated and when confronted with a surprise effect combined with the appearance of a novel object. This reduction in fearfulness may be mediated principally through reduced fear of isolation. However, fear of a human remained constant despite pregnancy. Fear reactions of ewes tested during isolation on gestation day 40 or 140 did not differ, suggesting that decreased fear is not restricted to the latest stage of pregnancy. A negative correlation was found between plasma progesterone levels and fear during isolation and surprise tests of ewes with low levels of progesterone. The decrease in fearfulness during pregnancy may have some adaptative value for the survival of the young.
M Viérin; M F Bouissou
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Physiology & behavior     Volume:  72     ISSN:  0031-9384     ISO Abbreviation:  Physiol. Behav.     Publication Date:  2001 Mar 
Date Detail:
Created Date:  2001-04-03     Completed Date:  2001-05-24     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0151504     Medline TA:  Physiol Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  579-87     Citation Subset:  IM    
I.N.R.A., Physiologie de la Reproduction, 37380 Nouzilly, France.
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MeSH Terms
Fear / psychology*
Pregnancy, Animal / psychology*
Progesterone / blood
Social Isolation
Reg. No./Substance:

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