| Functional similarity in relation to the external environment between circadian behavioral and melatonin rhythms in the subtropical Indian weaver bird. | |
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MedLine Citation:
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PMID: 22314320 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The present study investigated whether the circadian oscillators controlling rhythms in activity behavior and melatonin secretion shared similar functional relationship with the external environment. We simultaneously measured the effects of varying illuminations on rhythms of movement and melatonin levels in Indian weaver birds under synchronized (experiment 1) and freerunning (experiment 2) light conditions. In experiment 1, weaverbirds were exposed to 12h light: 12h darkness (12L:12D; L=20lx, D=0.1lx) for 2.5weeks. Then, the illumination of the dark period was sequentially enhanced to 1-, 5-, 10-, 20- and 100lx at the intervals of about 2 to 4weeks. In experiment 2, weaver birds similarly exposed for 2.5weeks to 12L:12D (L=100lx; D=0.1lx) were released in constant dim light (LL(dim), 0.1lx) for 6weeks. Thereafter, LL(dim) illumination was sequentially enhanced to 1-, 3- and 5lx at the intervals of about 2weeks. Whereas the activity of singly housed individuals was continuously recorded, the plasma melatonin levels were measured at two time of the day, once in each light condition. The circadian outputs in activity and melatonin were phase coupled with an inverse phase relationship: melatonin levels were low during the active phase (light period) and high during the inactive phase (dark period). This phase relationship continued in both the synchronized and freerunning states as long as circadian activity and melatonin oscillators subjectively interpreted synchronously the daily light environment, based on illumination intensity and/or photophase contrast, as the times of day and night. There were dissociations between the response of the activity rhythms and melatonin rhythms in light conditions when the contrast between day and night was much reduced (20:10lx) or became equal. We suggest that circadian oscillators governing activity behavior and melatonin secretion in weaverbirds are phase coupled, but they seem to independently respond to environmental cues. This would probably explain the varying degree to which the involvement of pineal/melatonin in regulation of circadian behaviors has been found among different birds. |
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Authors:
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Jyoti Singh; Sangeeta Rani; Vinod Kumar |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-1-31 |
Journal Detail:
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Title: Hormones and behavior Volume: - ISSN: 1095-6867 ISO Abbreviation: - Publication Date: 2012 Jan |
Date Detail:
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Created Date: 2012-2-8 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0217764 Medline TA: Horm Behav Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2012. Published by Elsevier Inc. |
Affiliation:
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Department of Zoology, University of Delhi, Delhi 110007, India. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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