The findings, reported in the November 4, 2005 issue of the journal Cell, demonstrate for the first time that the neuronal pathways that help to keep body weight stable diverge at the melanocortin-4 receptor (MC4R) to regulate either food intake or energy expenditure.
This unexpected discovery helps to extend the understanding of the complex neurocircuitry behind body weight control, an endeavor that began more than a decade ago with the identification of the leptin hormone and which has been growing steadily ever since.
"Maintaining a stable body weight is a delicate balancing act between the amount of food eaten versus the number of calories burned," says Bradford B. Lowell, MD, PhD, of BIDMC's department of endocrinology, diabetes and metabolism who, together with Joel K. Elmquist, DVM, PhD, served as co-senior author of the study. "The brain controls both food intake and calories expended with the purpose of keeping body weight stable. When something goes wrong with this process, obesity results. The findings of this new research provide us with more precise information about the neuronal pathways regulating this balance."
Body weight maintenance can be viewed as an intricate process made up of three basic elements, say Lowell and Elmquist, both of whom are also associate professors of medicine at Harvard Medical School (HMS). In the first, the brain receives sensory input from the body (including information provided by circulating hormones such as leptin and ghrelin and from fuels such as glucose and fatty acids). It then integrates this sensory information with cues it has received from the outside world (such as aromas and other enticements) along with information gather
Contact: Bonnie Prescott
Beth Israel Deaconess Medical Center