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Study: Brain Protein May Impact Eating Habits

Study: Brain Protein May Impact Eating HabitsLed by Maribel Rios, PhD, at Tufts School of Medicine, researchers have found that a protein in the brain may have some significant influence on the ability to feel full.

Boston [04.03.08] When faced with a fork and a plate of their favorite food, many people find themselves taking one bite too many. But what lies behind the act of overeating? Tufts neuroscientist Maribel Rios, PhD, has found that the brain's role in a satisfied stomach may be more important than you think.

In her laboratory at the Sackler School of Graduate Biomedical Sciences at the Tufts School of Medicine in Boston, Rios and her colleagues have demonstrated that BDNF (brain-derived neurotrophic factor) is an essential component in neural circuits which regulate body weight in adult mice.

Their findings, published in The Journal of Neuroscience, were the topic of discussion for an interview with Norman Swan of The Health Report on ABC Radio National in Australia.

"We knew from previous studies that if you get rid of the Bdnf gene in the brain of mice you end up with animals that are dramatically obese because they eat too much and they don't know when to stop eating," Rios told Radio National. "The extent of the obesity was very impressive; rarely in the literature do you find examples of mutant [mice] in which to get rid of a single molecule you end up with such a dramatic outcome."

Though it was known that the lack of BDNF could lead to overeating in young mice, it was still unclear whether BDNF arbitrated overindulgence in adult mice, according to Rios, an assistant professor of neuroscience at the Medical School.

"Our recent findings demonstrate that BDNF synthesis in the ventromedial and dorsomedial hypothalamus is required for normal energy balance," Rios said in a Tufts University news release. "Additionally, because the mice examined in this study were genetically altered in adulthood, we were able to establish that BDNF acts as a satiety signal in the mature brain independently from its putative actions during development of the brain. This important distinction might help define disease mechanisms and critical periods of intervention for the treatment and prevention of obesity disorders."

So how does BDNF affect the human brain?

"As it turns out it has been estimated that more than a quarter of the American population carries a mutation in the Bdnf gene and if you have that mutation you're more likely to develop obesity, but more work needs to be done for sure," Rios told Radio National. "But given that there's such a high prevalence of that mutation within the human population you would imagine, seeing what we see in the [mice], that perhaps carrying such a mutant form of the allele can create a propensity or susceptibility to develop obesity disorders."

Aside from playing a role in appetite control, Rios noted that BDNF can also be related to mood factors, such as depression and anxiety, and has also been "implicated in glucose metabolism in the liver," and as a very important factor in the development of the cardiovascular system.

"However, when you think again... about individuals that carry mutations in the Bdnf gene, you expect that they're going to have the full range of deficits associated with deficits in this pathway," Rios said.

Rios later noted, "So for them, intervention therapies involving the BDNF pathway would be ideal as they probably would alleviate more than one problem. For individuals that are obese but due to something other than deficiencies in BDNF then side effects associated with BDNF-related therapy might be more of a concern. Future studies will help address this."

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