Ghrelin: Peptide Can Boost Learning and Fight Dementia

Ghrelin is a peptide hormone known to be produced in the stomach and the hypothalamus. When the stomach is empty, ghrelin is produced, stimulating hunger in the brain via the "orexin pathway." Now we are learning that ghrelin does more than simply stimulate the appetite. Ghrelin may hold one of the keys to improving learning and blocking dementia. In addition, new drugs for combatting the obesity epidemic and other conditions may likely be found from research into ghrelins and the orexin pathway.

Eurekalert presents this newsrelease that introduces research on ghrelin from Yale University.

Researchers at Yale School of Medicine have found evidence that a hormone produced in the stomach directly stimulates the higher brain functions of spatial learning and memory development, and further suggests that we may learn best on an empty stomach.

Published in the February 19 online issue of Nature Neuroscience by investigators at Yale and other institutes, the study showed that the hormone ghrelin, produced in the stomach and previously associated with growth hormone release and appetite, has a direct, rapid and powerful influence on the hippocampus, a higher brain region critical for learning and memory.

The team, led by Tamas L. Horvath, chair and associate professor of the Section of Comparative Medicine at Yale School of Medicine, and associate professor in the Department of Obstetrics, Gynecology & Reproductive Sciences, and Neurobiology, first observed that peripheral ghrelin can enter the hippocampus and bind to local neurons promoting alterations in connections between nerve cells in mice and rats. Further study of behavior in the animals showed that these changes in brain circuitry are linked to enhanced learning and memory performance.

Because ghrelin is highest in the circulation during the day and when the stomach is empty, these results also indicate that learning may be most effective before meal-time.

....Horvath said that high ghrelin levels or administration of ghrelin-like drugs could also protect against certain forms of dementia, because aging and obesity are associated with a decline in ghrelin levels and an increased incidence of conditions of memory loss like Alzheimer's disease.

Here is more about the Orexin pathway and its activities. Ghrelin also acts to stimulate growth hormone secretion. This is one peptide hormone that holds a lot of promise.