BIDMC Researchers Discover How to Short Circuit Hunger
By Bonnie Prescott
Beth Israel Deaconess Medical Center staff
Anyone who has ever been on a low-calorie diet knows that it’s no fun to feel hungry. But how exactly does hunger develop, and why does hunger go away when you eat?
Grumblings may sound like they’re coming from your stomach, but in fact, hunger signals originate in your brain.
“Hunger is a mechanism that ensures human survival,” says Bradford Lowell, MD, PhD, a researcher in Beth Israel Deaconess Medical Center’s Center for Nutrition and Metabolism in the Division of Endocrinology, Diabetes and Metabolism. “Hunger tells the body when energy reserves are low and food is needed to avoid starvation. That’s why when you cut back on calories while trying to lose weight, you are likely to experience incessant hunger pangs — they are your body’s warning signals.”
Lowell’s laboratory has spent the past 20 years creating a “wiring diagram” of the brain’s complex neuro-circuits that underlie hunger, feeding and appetite. In April 2015, he published a new study in the journal Nature Neuroscience that specifically identifies the brain circuit that switches hunger on and off.
“We used a variety of new light-based and chemical-based technologies to study the brains of genetically engineered mice,” Lowell (right) explains. “These sophisticated tools helped us view the brain circuitry and see that a particular group of brain cells called the melanocortin 4 receptors were playing key roles in both generating and squelching appetite — determining whether an animal was hungry or not hungry.”
These detailed images of the brain circuitry may help point the way toward the development of targeted anti-obesity drugs.
“We have to be careful because these particular MC4R receptors also play other key roles in the body, including regulating blood pressure and heart rate,” says Lowell. “As we identify ever more precise details about the hunger circuits, we can potentially focus on just the appetite-causing MC4R neurons as an anti-obesity drug target.”
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