Document Detail

Internal synchronization among several circadian rhythms in rats under constant light.
MedLine Citation:
PMID:  727286     Owner:  NLM     Status:  MEDLINE    
Three biological rhythms (locomotor activity, body temperature, and plasma corticosterone) were measured simultaneously in individual rats under light-dark cycles and continuous light. Spontaneous locomotor activity was recorded on an Animex and body temperature was telemetrically monitored throughout the experiments. Blood samples were obtained serially at 2-h intervals on the experimental days. Phase angles of these rhythms were calculated by a least-squares spectrum analysis. Under light-dark cycles, the acrophases of locomotor activity, body temperature, and plasma corticosterone were found at 0029, 0106, and 1940 h, respectively. When rats were exposed to 200 lx continuous light, locomotor activity and body temperature showed free-running rhythms with a period of 25.2 h on the average. Plasma corticosterone levels determined at 12 days after exposure to continuous light exhibited a circadian rhythm with the acrophase shifted to 0720. The acrophases of locomotor activity and body temperature, determined simultaneously on the same day, were found to be located at 1303 and 1358 h, respectively. Phase-angle differences among the three rhythms on the 12th day of continuous light were essentially the same with those under the light-dark cycle. These results suggest that circadian rhythms of locomotor activity, body temperature, and plasma corticosterone are most probably coupled to a common internal oscillator in the rat.
K I Honma; T Hiroshige
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The American journal of physiology     Volume:  235     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1978 Nov 
Date Detail:
Created Date:  1979-02-21     Completed Date:  1979-02-21     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R243-9     Citation Subset:  IM    
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MeSH Terms
Biological Clocks / radiation effects*
Body Temperature
Circadian Rhythm / radiation effects*
Corticosterone / blood
Motor Activity / physiology
Reg. No./Substance:

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