Tick tock! Researchers show the workings of the body clock
We all know that feeling when spring arrives and the days start to get longer. Our energy levels increase and we feel healthier, more active and more positive. But the questions remain: why do we feel this way, and what are the mechanisms that control this internal body clock? A research team from the UK has discovered the processes that control seasonal changes in hormones. The findings, published in the journal Current Biology, could help lead to treatments for seasonal affective disorder (SAD). The researchers from the Universities of Edinburgh and Manchester discovered two genes - EYA3 and TAC1 - that are activated when hormone levels rise as the days get longer in spring. The team found that TAC1 was only activated when EYA3 was present, fuelling speculation that part of EYA3's role is to regulate TAC1 so it can be activated when the days get longer. Interestingly, the gene EYA3 plays a similar role in both mammals and birds - a link that has been preserved for millions of years. Thousands of genes in a breed of sheep called Soay, which comes from the western isles of Scotland, were studied. The team used Soay sheep because they are considered to be one of the most primitive types of sheep (they date back to the Bronze Age), so their body clocks are unaffected by cross breeding. The researchers assessed the role of a key molecule called tuberalin, which they suspected was produced in the pituitary gland at the base of the brain, sending signals to hormones that are involved in controlling seasonal changes in the body. Until now, little was known about the nature and role of tuberalin. A part of the brain that responds to the hormone melatonin - a key player in the seasonal timings of the body - was also put under the microscope. The researchers discovered a candidate molecule for tuberalin which sends signals to the pituitary gland when the days begin to get longer. The pituitary gland then stimulates the release of the hormone prolactin, which helps mammals adapt to longer hours of light and other seasonal changes. Commenting on the results of the study, Professor Dave Burt from the Roslin Institute at the University of Edinburgh said: 'For more than a decade scientists have known about the presence of this mysterious molecule tuberalin, but until now nobody has known quite how it worked. 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.' Professor Andrew Loudon from the University of Manchester's Faculty of Life Sciences said, '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.'
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