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: A sneaky snake: Teams hunt for rock pythons in Everglades

add to favorites email to friend print save as pdf

Related Stories

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 ...

Scientists revise timeline of human origins

Jul 03, 2014

Many traits unique to humans were long thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa. Although scientists have recognized these characteristics for decades, they a ...

Robot gliders roam seas

May 03, 2013

(Phys.org) —Once the robotic gliders scour the ocean searching for potential harm to sea life, the data is sent to David Caron, professor of biological sciences in USC Dornsife, and other marine biologists. ...

Recommended for you

A rare glimpse at the elusive saharan cheetah

12 hours ago

Research by scientists and conservationists from the Wildlife Conservation Society, the Zoological Society of London, and other groups published today in PLOS ONE shows that critically endangered Saharan cheeta ...

In a role reversal, RNAs proofread themselves

13 hours ago

Building a protein is a lot like a game of telephone: information is passed along from one messenger to another, creating the potential for errors every step of the way. There are separate, specialized enzymatic ...

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.