| Persistent diel melatonin rhythmicity during the Arctic summer in free-living willow warblers. | |
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MedLine Citation:
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PMID: 19374903 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Arctic environments are challenging for circadian systems. Around the solstices, the most important zeitgeber, the change between night and day, is reduced to minor fluctuations in light intensities. However, many species including songbirds nonetheless show clear diel activity patterns. Here we examine the possible physiological basis underlying diel rhythmicity under continuous Arctic summer light. Rhythmic secretion of the hormone melatonin constitutes an important part of the songbird circadian system and its experimental suppression, e.g., by constant light, usually leads to behavioral arrhythmia. We therefore studied melatonin patterns in a free-living migratory songbird, the willow warbler (Phylloscopus trochilus), that maintains diel activity during the Arctic summer. We compared melatonin profiles during late spring and summer solstice in two Swedish populations from the south (58 degrees N) and near the Arctic circle (66 degrees N). We found the northern Swedish population maintained clear diel changes in melatonin secretion during the summer solstice, although peak concentrations were lower than in southern Sweden. Melatonin levels were highest before midnight and in good accordance with periods of reduced activity. The maintenance of diel melatonin rhythmicity under conditions of continuous light may be one of the physiological mechanisms that enables continued functioning of the circadian system. |
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Authors:
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Bengt Silverin; Eberhard Gwinner; Thomas J Van't Hof; Ingrid Schwabl; Leonida Fusani; Michaela Hau; Barbara Helm |
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Publication Detail:
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Type: Journal Article Date: 2009-04-15 |
Journal Detail:
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Title: Hormones and behavior Volume: 56 ISSN: 1095-6867 ISO Abbreviation: Horm Behav Publication Date: 2009 Jun |
Date Detail:
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Created Date: 2009-06-01 Completed Date: 2009-08-21 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0217764 Medline TA: Horm Behav Country: United States |
Other Details:
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Languages: eng Pagination: 163-8 Citation Subset: IM |
Affiliation:
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Department of Zoology, University of Gothenburg, Gothenburg, Sweden. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Animals, Wild Arctic Regions Circadian Rhythm / physiology* Melatonin / blood* Motor Activity / physiology Periodicity Photoperiod Radioimmunoassay Seasons* Songbirds / physiology* |
| Chemical | |
Reg. No./Substance:
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73-31-4/Melatonin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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