Decades-Long Scientific Research Reveals Secret to Sheep Sex During Winter

Decades-Long Scientific Research Reveals Secret to Sheep Sex During Winter

NOTTINGHAM, 09-Mar-2017 — /EuropaWire/ — Scientists have discovered for the first time how animals link the change in seasons to their fertility.

A study, led by academics at the Universities of Nottingham and Bristol and published in the journal Proceedings of the National Academy of Sciences (PNAS), reveals the link between breeding season and the hormone melatonin, made in the pineal gland in the brain during long winter nights.

Joint senior author David Bates, Professor of Oncology in the School of Medicine at The University of Nottingham, said: “Changes during the year in sex hormones made in the pituitary gland control when mammals start reproducing, and other changes like growing new coats or developing antlers.

“The length of the day is recognised in most vertebrate animals by the pineal gland in the brain, which produces melatonin. However, until now, it has not been known how melatonin, which is produced at night, signals to the area of the pituitary gland that controls sex hormones.”

The team of scientists, which also included PhD student Dr Jennifer Castle-Miller and Dr Domingo Tortonese, in the Faculty of Health Sciences at the University of Bristol, found that in sheep, melatonin controls production of two different types of a protein called vascular endothelial growth factor (VEGF). This happens within a specific region of the pituitary gland, away from the area where sex hormones are made.

In winter, sheep make forms of VEGF that stop blood vessels growing. In summer, they make a different VEGF that makes vessels grow between the two areas of the pituitary. This allows VEGF to act as a messenger to control sex hormone-producing cells and fertility – the first time that the molecule linking long winter nights to sex hormones has been found.

The search for the missing link between the different parts of the pituitary has been going on for nearly 30 years, because knowing how this works could, for instance, help control when sheep start lambing, enabling farmers to respond to climate change. The findings also have wider implications for how animals, and potentially humans, use this system in health and disease.

The scientific paper Mechanisms Regulating Angiogenesis Underlie Seasonal Control of Pituitary Function is published by PNAS and will be available on the PNAS website after the embargo has lifted.

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Story credits

More information is available from Professor David Bates in the School of Medicine, University of Nottingham on +44 (0)115 823 1135, david.bates@nottingham.ac.uk or Emma Thorne, Media Relations Manager for the Faculty of Medicine and Health Sciences in the Communications Office at The University of Nottingham, on +44 (0)115 951 5793, emma.thorne@nottingham.ac.uk

Emma Thorne – Media Relations Manager

Email: emma.thorne@nottingham.ac.uk
Phone: +44 (0)115 951 5793
Location: University Park

SOURCE: The University of Nottingham