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Circadian and seasonal rhythms of melatonin production in mules ( Equus asinus × Equus caballus )
Author(s) -
Cozzi Bruno,
Morei Giovanni,
Ravault JeanPaul,
Chesneau Didier,
Reiter Russel J.
Publication year - 1991
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.1991.tb00829.x
Subject(s) - melatonin , equus , equus asinus , circadian rhythm , morning , donkey , horse , biology , endocrinology , medicine , rhythm , zoology , ecology , botany , paleontology
The present study describes the patterns of melatonin production in the mule ( Equus asinus × Equus caballus ). Blood was sampled hourly for 24 h from eight mule mares in spring and fall. The data obtained show the presence of a circadian rhythm of production of melatonin, with highest values during the dark phase both in spring and fall. In fall the nightly rise of melatonin production begins earlier in the dark phase and reaches higher quantitative levels than in spring. The morning decline of melatonin production is similar in the two seasons. Maximal levels of nightly melatonin production in the mule are about 10× higher than those described in the horse. The results reported here indicate the persistence of brain structures able to receive and transduce environmental signals in the mule, a genetically sterile mammalian hybrid.