Key hormone involved in appetite control

The hormone, called ghrelin, has been found to be involved in weight regulation or reduced caloric intake.

RESEARCHERS AT Oregon Health and Science University (OHSU) have identified a key hormone involved in appetite control and demonstrated its effect on the brain.

Scientists have presently shown that the hormone, called ghrelin, activates specialized neurons in the hypothalamus involved in weight regulation.

The research involved scientists at several collaborating institutions, including: Yale Medical School, Baylor College of Medicine, the University of Alberta and Lilly Research Laboratories.

The results are printed in Neuron. Researchers believe this information could be used to develop drugs aimed at stimulating appetite in patients who have undergone extreme weight loss due to illness, a condition known as cachexia.

These pharmaceuticals could also assist children who are developing at a slower than normal rate.

Conversely, drugs aimed at limiting production of the hormone might be developed to reduce appetite for those battling severe obesity.

"Ghrelin is a hormone produced in the stomach with the natural ability to stimulate feeding when introduced to specialized weight regulation brain cells called neuropeptide Y neurons.

In fact, past research has shown that when ghrelin levels are increased in mice for an extended period, the mice gain weight," said Michael Cowley, an assistant scientist in the Division of Neuroscience at the OHSU Oregon National Primate Research Center .

"In both mice and humans, ghrelin levels increase naturally in response to weight loss or reduced caloric intake. As expected, the hormone diminishes in response to food intake. In other words, it's believed to be part of the body's natural signalling system which informs the brain when it's time to eat."

To pinpoint and witness the effects of ghrelin in the brain, the researchers used a fluorescent protein to highlight certain neurons, making the brain cells distinguishable from other surrounding neurons.

They then used tiny electrodes to record cell activity in response to ghrelin.

The research team also located a new source for ghrelin production in the body. The site is located in a section of the hypothalamus that had no previously known function and that is near the brain region affected by the hormone.

The research further shows that there are two sites where increased appetite may be generated, the stomach and the brain.