Discovery Shows How Brain Stimulates Hunger

WEDNESDAY, Jan. 3 (HealthDay News) -- Researchers from the Yale University School of Medicine have uncovered a complex series of events in the brain that stimulate hunger during fasting.

A study published in the January issue of Cell Metabolism found that during periods of fasting, a cascade of events in the brain makes sure you stay hungry when food is scarce.

The researchers revealed that thyroid hormone in the brain is associated with increases in an "uncoupling" protein known as UCP2, which boosts the number of power-generating mitochondria in neurons that drive hunger.

When mice were fasted for 24 hours, the researchers found there was an increase in the enzyme that stimulates thyroid hormone production in concert with increased UCP2 activity.

The UCP2 activation resulted in a proliferation of mitochondria in the neurons, which increased the brain cells' excitability and resulted in "rebound feeding" in the mice after a period of food deprivation.

The mice that lacked either UCP2 or the thyroid-stimulating enzyme ate less than normal after they were fasted.

"This shows the key importance of UCP in the brain and its effect on neuronal activity," lead researcher Sabrina Diano said in a prepared statement. "It's how neurons 'learn' that food is missing, and it keeps them ready to eat when food is introduced."