Document Detail

Enhancement and suppression of ultradian and circadian rhythms across the female hamster reproductive cycle.
MedLine Citation:
PMID:  22653893     Owner:  NLM     Status:  MEDLINE    
The impact of ovarian hormones on hamster ultradian rhythms (URs) is unknown. We concurrently monitored URs and circadian rhythms (CRs) of home cage locomotor activity during the estrous cycle, pregnancy, and lactation of Syrian hamsters. URs with a mean period of 4-5 h were evident during the dark phase in more than 90% of females on days 1 and 2 of the estrous cycle but were significantly less prevalent on cycle days 3 and 4. The period of the UR did not vary as a function of estrous cycle stage, but at all stages, the UR period was longer in the dark than the light phase. The UR acrophase occurred significantly earlier on cycle day 4 than on days 1 and 2, and UR robustness and amplitude were reduced on days 3 and 4. Robustness, mesor, and amplitude of CRs were greater during cycle days 3 and 4; timing of the CR acrophase was delayed on day 4 relative to all other cycle days. Effects of the estrous cycle on URs were evident only during the dark phase. The proportion of hamsters displaying dark phase URs increased significantly during early and late gestation and decreased during lactation. Pregnancy significantly increased UR complexity, robustness, and amplitude. The emergence of URs over gestation was paralleled by decrements in the robustness and amplitude of CRs, which also were absent in a significant proportion of dams during lactation but re-emerged at weaning of litters. The changing endocrine profile of the estrous cycle, hormonal dynamics of pregnancy and lactation, and nursing demands placed on dams are each associated with alterations in the expression of ultradian and circadian locomotor rhythms. Diminution of CRs and augmentation of URs may afford greater behavioral flexibility during life stages when interactions with mates and offspring are less predictable.
Brian J Prendergast; Annaliese K Beery; Matthew J Paul; Irving Zucker
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  27     ISSN:  1552-4531     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-06-01     Completed Date:  2012-10-09     Revised Date:  2014-03-28    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  United States    
Other Details:
Languages:  eng     Pagination:  246-56     Citation Subset:  IM    
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MeSH Terms
Circadian Rhythm*
Estrous Cycle
Hormones / metabolism
Models, Biological
Models, Statistical
Ovary / metabolism
Pregnancy, Animal
Reproduction / physiology*
Time Factors
Grant Support
Reg. No./Substance:

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