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The Effects of Photoperiod and Melatonin on Serum Prolactin Levels of Mink During the Autumn Molt
Author(s) -
Rose Jack,
Stormshak Fredrick,
Oldfield James,
Adair John
Publication year - 1985
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.1985.tb00624.x
Subject(s) - melatonin , mink , photoperiodism , prolactin , endocrinology , medicine , biology , hormone , ecology
An experiment was conducted to determine the effects of a reduced daily photoperiod and exogenous melatonin on serum prolactin levels of mink during the autumn molt and growth of the winter pelage. During the last week of June, adult standard dark female mink ( Mustela vison ) were exposed to natural changes in daylength (controls), a reduced photoperiod of 6 h light: 18 h dark (6L: 18D) or exposure to natural changes in daylength and treated with melatonin (10 mg) in a Silastic implant inserted subcutaneously over the scapular area. Beginning July 2, and continuing through October 22, blood samples were collected at nine biweekly intervals, and serum prolactin concentrations were quantified by a heterologous double antibody radioimmunoassay. Both reduced photoperiod and exogenous melatonin caused serum prolactin levels to decline rapidly after mid‐July, resulting in concentrations that were significantly lower than those of controls 6 to 8 wk earlier. These data suggest that growth of the winter pelage of mink is strongly associated with declining prolactin levels. It appears that part of the photoperiodic‐induced effects on fur growth of the mink are mediated through melatonin and its effects on prolactin synthesis and/or secretion.