The role of dynorphins in energy homeostasis

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While it is clear that carrying excess body weight can jeopardize your health, and that losing excess weight is good for you, attaining and maintaining a healthy body weight remains an elusive goal for more than 60 % of Australian adults. There are many barriers that make permanent weight loss difficult. One of the main biological barriers to weight loss is that humans aren t designed to diet. Instead, we vehemently conserve body fat whenever food is scarce. This leads to a Famine Reaction that contributes to nagging hunger, lethargy, loss of libido, reduced metabolic rate, plateaus, and rebound weight gain in response to weight loss programs of any kind. In a new 3-year project funded by the National Health and Medical Research Council of Australia, molecular scientists Dr Amanda Sainsbury-Salis and Associate Professor Herbert Herzog from the Garvan Institute endeavor to get to the root of the problem. Using cutting-edge molecular, genetic, and metabolic technology, Sainsbury-Salis and Herzog aim to identify the main culprits for the Famine Reaction. They hypothesize that the natural brain molecules neuropeptide Y and the endogenous morphine-like peptide dynorphin act together as major instigators of the Famine Reaction. Therefore they will determine whether mice that are deficient in these molecules can lose more weight in response to dietary restriction than normal mice. Moreover, they will determine whether dual deficiency of neuropeptide Y and dynorphin can not only reduce the voracious appetite that occurs during caloric restriction (eg: dieting), but whether it can also speed up metabolism and promote the loss of body fat. If their hypothesis proves correct, then it s likely that novel pharmaceutical agents that block the effects of neuropeptide Y and dynorphin could dramatically increase the do-ability and long-term effectiveness of lifestyle changes for permanent weight loss.