Document Detail

Reproductive refractoriness of the ewe to inductive photoperiod is not caused by inappropriate secretion of melatonin.
MedLine Citation:
PMID:  3620566     Owner:  NLM     Status:  MEDLINE    
The 24-h pattern of melatonin secretion was evaluated in Suffolk ewes during prolonged exposure to an inductive photoperiod to assess whether altered secretion of melatonin could account for the eventual loss of response to stimulatory photoperiod (photorefractoriness). Secretory patterns of melatonin were determined approximately every two weeks in samples obtained hourly for 24-48 h. Sampling was begun one week before the switch from inhibitory (long) to inductive (short) photoperiod and continued for 150 days, by which time all but one of the ewes were unresponsive to that stimulatory day length. Melatonin was measured in two different radioimmunoassay systems. Reproductive state was monitored by luteinizing hormone secretion in ovariectomized ewes bearing constant-release estradiol implants. No evidence for disruption of the melatonin pattern was observed on any occasion. The duration and the phase of the melatonin elevation relative to the light/dark cycle did not vary with time of exposure to short days. These findings indicate that refractoriness of the Suffolk ewe to an inductive photoperiod is not caused by an inappropriate secretory pattern of melatonin.
B Malpaux; J E Robinson; M B Brown; F J Karsch
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biology of reproduction     Volume:  36     ISSN:  0006-3363     ISO Abbreviation:  Biol. Reprod.     Publication Date:  1987 Jun 
Date Detail:
Created Date:  1987-10-07     Completed Date:  1987-10-07     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0207224     Medline TA:  Biol Reprod     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1333-41     Citation Subset:  IM    
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MeSH Terms
Environment, Controlled
Luteinizing Hormone / blood
Melatonin / secretion*
Time Factors
Grant Support
Reg. No./Substance:
73-31-4/Melatonin; 9002-67-9/Luteinizing Hormone

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