The effect of melatonin on the seasonal embryonic diapause of the Bennett's wallaby (Macropus rufogriseus rufogriseus)

Authors

  • A. S. I. Loudon,

    1. MRC/AFRC Comparative Physiology Research Group, The Institute of Zoology, The Zoological Society of London, Regent's Park, London NW1 4RY
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  • J. D. Curlewis,

    1. MRC/AFRC Comparative Physiology Research Group, The Institute of Zoology, The Zoological Society of London, Regent's Park, London NW1 4RY
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  • J. English

    1. MRC/AFRC Comparative Physiology Research Group, The Institute of Zoology, The Zoological Society of London, Regent's Park, London NW1 4RY
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    • *Department of Biochemistry, University of Surrey, Guildford GU2 5XH.


Abstract

In seasonally breeding mammals, the hormone melatonin, produced at night by the pineal gland, is known to be important in transducing the effect of photoperiod in timing reproduction. In the Bennett's wallaby, an unimplanted unilaminar blastocyst is held in a state of seasonal diapause from mid-winter to mid-summer. Here we show that an implant of the hormone melatonin rapidly terminates seasonal diapause in this species. Blastocyst reactivation is not accompanied by a significant reduction in levels of the hormone prolactin, thereby refuting earlier suggestions that this hormone is responsible for maintaining seasonal embryonic diapause.

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