In patients suffering Prader-Willi syndrome it has been shown that there is a greatly elevated level of a hormone known as ghrelin. This hormone is known to normally stimulate hunger and food intake. However, the levels of the circulating hormone leptin that signals the need to reduce food intake and increase energy expenditure is not similarly up regulated. Consequently it is possible that the imbalance between these hormones is responsible for the insatiable appetite of Prader-Willi sufferers. It is feasible that if the effects of ghrelin could be blocked, these symptoms could be relieved.
Before this can become a reality, it is first necessary to fully appreciate how this hormone works to stimulate hunger. We believe that it does so by acting upon a specific group of neurons in the brain. So far the actions of ghrelin on these neurons has not been studied because up to now they have difficult to identify. However, the applicants have now resolved this problem and are in a position where they can explore how ghrelin works in these neurons to stimulate appetite. The long-term aim of these studies is to identify drugs which will regulate the action of this hormone and are therefore able to regulate appetite in those individuals where is it overproduced such as in the case of Prader-Willi patients.
David Spanswick, Ph.D
Department of Neuroscience, University of Warwick, UK