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Diurnal Variations of Plasma Melatonin Concentrations in Pregnant or Pseudopregnant Mink ( Mustela vison ) Maintained Under Different Photoperiods
Author(s) -
Ravault J. P.,
Martinet L.,
Bonnefond C.,
Claustrat B.,
Brun J.
Publication year - 1986
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1986.tb00758.x
Subject(s) - melatonin , mink , endocrinology , medicine , biology , prolactin , radioimmunoassay , circadian rhythm , luteal phase , estrous cycle , hormone , ecology
Removal of the superior cervical ganglia suppresses the inhibitory role of short days in prolactin secretion and luteal activity in pregnant or pseudopregnant mink. Alternatively, timed injections of melatonin replicate the inhibitory role of short days in females maintained under long days. To understand if the diurnal variation of melatonin secretion is part of the mechanism by which the mink measure day length, diurnal variations in plasma melatonin concentrations have been measured in intact and ganglionectomized females maintained under long or short days after mating. Melatonin was measured by radioimmunoassay according to Brun et al. [Adv. Biosci. 53: 41–45]. In intact females, plasma concentrations ranged from nondetectable levels to 40 pg/ml during the day, increased shortly after the onset of the dark phase, and reached peak values during the middle of the night. The duration of the elevated levels was roughly proportional to the length of the night. No diurnal variations could be detected in ganglionectomized females; melatonin levels never exceeded the day values observed in intact females.