Linked Life Data

9370209

Source:http://linkedlifedata.com/resource/pubmed/id/9370209

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1997-12-23
pubmed:abstractText
The pineal organ and its hormone melatonin are significant components of avian circadian pacemaking systems. In songbirds, pinealectomy results in the abolition or destabilization of overt circadian rhythms such as the rhythm of locomotor activity, feeding, or body temperature. A stable rhythmicity can be restored either by reimplanting a pineal organ, by periodic injections or infusions of melatonin, or by applying melatonin rhythmically through the drinking water. Several results suggest that the pineal melatonin rhythm acts on at least one other oscillator within the circadian pacemaking system, presumably the SCN, which in turn, feeds back to the pineal. As described by the "Neuroendocrine Loop" and "Internal Resonance" models, overall pacemaker output thus depends on the relative strengths of the oscillations in the pineal and the SCN. Investigations on migratory birds have shown that the amplitude of the 24-h plasma melatonin rhythm is reduced during the migratory seasons compared with the nonmigratory seasons. According to the models mentioned above, such a reduced melatonin amplitude should result in a reduction in the degree of self-sustainment of the pacemaker as a whole. This, in turn, should facilitate adjustment to the altered Zeitgeber conditions encountered by these birds as a result of their own migratory flights. A seasonal reduction in melatonin amplitude also occurs in some high-latitude birds during midsummer and midwinter. Under such conditions a less self-sustained circadian pacemaker may enhance entrainability to weak zeitgeber conditions. These examples suggest that the properties of the circadian system may be adjusted to match the changing requirements for synchronization, and that this is achieved by altering the melatonin amplitude.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0361-9230
pubmed:author
pubmed:issnType
Print
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
439-44
pubmed:dateRevised
2005-11-16
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Melatonin: generation and modulation of avian circadian rhythms.
pubmed:affiliation
Max-Planck-Institut für Verhaltensphysiologie, Andechs, Germany.
pubmed:publicationType
Journal Article, Review