Document Detail

Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles.
MedLine Citation:
PMID:  23003567     Owner:  NLM     Status:  MEDLINE    
The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within ≈ 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion.
Evan E Raiewski; Jeffrey A Elliott; Jennifer A Evans; Gena L Glickman; Michael R Gorman
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-09-24
Journal Detail:
Title:  Chronobiology international     Volume:  29     ISSN:  1525-6073     ISO Abbreviation:  Chronobiol. Int.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-10-09     Completed Date:  2013-02-25     Revised Date:  2014-01-21    
Medline Journal Info:
Nlm Unique ID:  8501362     Medline TA:  Chronobiol Int     Country:  England    
Other Details:
Languages:  eng     Pagination:  1206-15     Citation Subset:  IM    
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MeSH Terms
Circadian Rhythm / physiology*
Melatonin / blood,  secretion*
Mesocricetus / blood,  physiology*
Motor Activity / physiology
Phodopus / blood,  physiology*
Species Specificity
Grant Support
Reg. No./Substance:

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