Blood cells control appetite by homing into specific regions in the brain, reports a study published in Nature Communications this week. The finding provides new insight into the regulation of appetite in mice and may lead to the development of new therapies for eating disorders.

Brain-derived neurotrophic factor (BDNF) is a protein produced locally in the brain, where it regulates feeding behaviour. BDNF is also found in blood cells, which can migrate into the brain under conditions such as inflammation. Investigating whether blood cells have a role in regulating appetite Hideto Kojima and colleagues found that fasting triggered the migration of blood cells into the hypothalamus - a brain region known to be key in regulating appetite - where they made contacts with local neurons and produced a blood-cell-specific variant of BDNF. The go on to report that mice with genetic BDNF defects in blood cells ate more than normal mice and became obese, but decreased their food intake when these genetic defects were restored by bone marrow transplants.