Document Detail

Effects of square-wave and simulated natural light-dark cycles on hamster circadian rhythms.
MedLine Citation:
PMID:  10198403     Owner:  NLM     Status:  MEDLINE    
Circadian rhythms of activity (Act) and body temperature (Tb) were recorded from male Syrian hamsters under square-wave (LDSq) and simulated natural (LDSN, with dawn and dusk transitions) light-dark cycles. Light intensity and data sampling were under the synchronized control of a laboratory computer. Changes in reactive and predictive onsets and offsets for the circadian rhythms of Act and Tb were examined in both lighting conditions. The reactive Act onset occurred 1.1 h earlier (P < 0.01) in LDSN than in LDSq and had a longer alpha-period (1.7 h; P < 0.05). The reactive Tb onset was 0.7 h earlier (P < 0.01) in LDSN. In LDSN, the predictive Act onset advanced by 0.3 h (P < 0.05), whereas the Tb predictive onset remained the same as in LDSq. The phase angle difference between Act and Tb predictive onsets decreased by 0.9 h (P < 0.05) in LDSN, but the offsets of both measures remained unchanged. In this study, animals exhibited different circadian entrainment characteristics under LDSq and LDSN, suggesting that gradual and abrupt transitions between light and dark may provide different temporal cues.
I H Tang; D M Murakami; C A Fuller
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  276     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1999 Apr 
Date Detail:
Created Date:  1999-05-13     Completed Date:  1999-05-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R1195-202     Citation Subset:  IM; S    
Section of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616-8519, USA.
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MeSH Terms
Behavior, Animal / physiology
Body Temperature / physiology
Circadian Rhythm / physiology*
Computer Simulation
Motor Activity / physiology
D M Murakami / U CA, Davis

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