Ancient sheep help pinpoint brain timing mechanisms linked to Seasonal Affective Disorder

Aug 13, 2008

(PhysOrg.com) -- New research by Aberdeen scientists suggests that Seasonal Affective Disorder (SAD) relates to an ancient timing mechanism in the brain dating back millions of years.

Discoveries by a University of Aberdeen-led team, involving collaborators in Edinburgh and Strasbourg, and published in the latest issue of Current Biology, shed new insights into the mechanisms by which seasonal rhythms are generated.

The researchers studied the primitive Soay breed of sheep, which relies on its strong seasonal biology to survive wild on the North Atlantic islands of St Kilda.

They identified a new role for a chemical known as thyroid stimulating hormone (TSH), which is secreted by cells in the pituitary gland and is already known to control the thyroid gland.

The new work reveals that a specialised group of pituitary TSH-secreting cells signal directly to the brain to control the sheep's seasonal behaviour.

This surprising discovery reverses the "master - slave" relationship between the brain and the pituitary, found in all vertebrates including humans, in which brain signals control pituitary hormone secretion.

Dr David Hazlerigg, Reader in Zoology at the University of Aberdeen said: "Our research points to an ancient seasonal timing mechanism that survives in modern vertebrates. Some humans may retain remnants of this ancient seasonal timing mechanism which would explain why they experience SAD.

It is now hoped that identifying this new role for TSH may lead to better understanding of seasonal or thyroid disorders in humans.

Dr Hazlerigg continues: "Our next target is to understand exactly what TSH does when it gets into the brain to cause changes in behaviour and hormone secretion. By defining these pathways we hope to increase our understanding not only of the control mechanisms in seasonal animals but also of SAD."

Provided by University of Aberdeen

Explore further: Researchers discover new mechanism of DNA repair

Related Stories

Our ancient obsession with food

Jun 05, 2015

Amateur cook-offs like the hugely popular Master Chef series now in its seventh season in Australia have been part of our TV diet for almost two decades. ...

Oldest-known stone tools pre-date Homo

May 20, 2015

Scientists working in the desert badlands of northwestern Kenya have found stone tools dating back 3.3 million years, long before the advent of modern humans, and by far the oldest such artifacts yet discovered. ...

Human races: biological reality or cultural delusion?

Aug 14, 2014

The issue of race has been in the news a lot lately with the canning of proposed amendments to Australia's Racial Discrimination Act, attempts by extremists to commit genocide on cultural minorities in Iraq and a new book by US autho ...

Recommended for you

Researchers discover new mechanism of DNA repair

Jul 03, 2015

The DNA molecule is chemically unstable giving rise to DNA lesions of different nature. That is why DNA damage detection, signaling and repair, collectively known as the DNA damage response, are needed.

The math of shark skin

Jul 03, 2015

"Sharks are almost perfectly evolved animals. We can learn a lot from studying them," says Emory mathematician Alessandro Veneziani.

Cuban, US scientists bond over big sharks

Jul 03, 2015

Somewhere in the North Atlantic right now, a longfin mako shark—a cousin of the storied great white—is cruising around, oblivious to the yellow satellite tag on its dorsal fin.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.