Ghrelin and growth hormone: Story in reverse

Abstract

The current epidemic of obesity and diabetes in the face of a surfeit of calories contrasts the natural selection to survive famine that confronted our ancestors. The report in PNAS by Zhao et al. (1) shows that ghrelin is an important hormone in this process. By studying mice under severe caloric restriction, they show that knockout (KO) of the enzyme ghrelin O-acyltransferase (GOAT), necessary to convert ghrelin to its active form, manifests the first clear phenotype seen in KO of ghrelin activity; ghrelin is necessary for triggering the growth-hormone (GH) response to nutritional deprivation that prevents hypoglycemia and death.