SAD genes identified

New treatments for SAD –seasonal affective disorder – may be on the cards thanks to research from Manchester and Edinburgh which discovered two genes that regulate the body clock.

Researchers discover genes which help to regulate the body clock

The genes – TAC1 and EYA3 – are activated early when natural hormone levels rise due to longer days. The study suggests TAC1 will only work with EYA3, which regulates TAC1 to switch it on in response to an increasing day length.

“Identifying these genes not only sheds light on how our internal annual body clocks function but also shows a key link between birds and mammals that has been conserved over 300 million years,” said Professor Dave Burt from the Roslin Institute at the University of Edinburgh.

Researchers studied genes in Soay sheep – a breed which dates back to the Bronze Ages – focusing on the part of the brain that responds to melatonin, a hormone known to be involved in seasonal timing in mammals

Scientists had speculated that a key molecule – tuberalin – was produced in the pituitary gland at the base of the brain and sent signals to release hormones involved in driving seasonal changes. But they had no idea about the nature of this molecule, how it works and how it is controlled.

Professor Burt said: “For more than a decade scientists have known about the presence of this mysterious molecule tuberalin, but until now nobody has quite known how it worked.”

As well as these two genes, the study revealed a candidate for tuberalin, which communicates within the pituitary gland to signal the release of prolactin when the days start getting longer, which helps animals adapt to seasonal changes.

“A lot of our behaviour is controlled by seasons. This research sheds new light on how animals adapt to seasonal change, which impacts on factors including hibernation, fat deposition and reproduction as well as the ability to fight off diseases,” said Professor Andrew Loudon from the University of Manchester.