July 14, 2011

A Natural Prevention for Obesity

(Ivanhoe Newswire)--For some time scientists have known the hormone leptin has acted in the brain to prevent obesity, but the mystery remains as to whether or not this is a natural weight loss treatment. Leptin has been described as our starvation hormone. It tells your brain when you have stored enough energy in your fat cells to engage in normal metabolic processes. Senior study author Dr. Bradford B. Lowell from Beth Israel Deaconess Medical Center and Harvard Medical School was quoted explaining leptin as "a hormone that is secreted by fat cells and acts as its receptor in the brain to decrease food intake and promote energy expenditure."

However, in those suffering from obesity, large amounts of leptin exist but do not send the necessary signals to the brain to stop eating once appropriate levels are reached. This occurrence is called "leptin resistance" as quoted by Robert H. Lustig, M.D., professor of pediatrics at the University of California, San Francisco and a member of the Endocrine Society's Obesity Task Force. Leptin's level can continue to rise as people gain more weight. If leptin levels are high, the brain can not recognize it and, in other words, is starved while the body is obese.

Previous studies conducted by Dr. Lowell's group focused on a region of the brain called the arcuate nucleus and declared it as the site of key components related to the control of obesity. In particular, proopiomelanocortin (POMC) neurons, which reside in this region of the brain, have been shown to play a major role in appetite suppression. In a recent study, Dr. Lowell and colleagues took a new approach to identifying "unidentifiable" body weight-regulating neurons and leptin's effects.

Their research showed that GABA, or glutamate neurons, predominately mediate the antiobesity effects of leptin. They found that these GABA neurons work with POMC neurons to facilitate antiobesity effects. Dr. Lowell was quoted as saying, "As POMC neurons prevent obesity, and their disinhibition by leptin action on upstream GABA neurons likely mediates, at least in part, leptin's antiobesity effects." Their study concluded that the indirect regulation of POMC neurons by leptin in the brain, reconcile the critical role POMC neurons have in regulating body weight and directing action of leptin.

SOURCE: Neuron, July 13, 2011