Magazine article Science News

Hunger for Knowledge: Appetite Hormone May Stimulate Memory

Magazine article Science News

Hunger for Knowledge: Appetite Hormone May Stimulate Memory

Article excerpt

A hormone that's been tied to hunger may also play a pivotal role in creating and retrieving memories, according to a study in mice. These findings could spur new strategies for improving learning and memory in people.

When the stomach is empty, its lining cells secrete a hormone called ghrelin. Previous studies have shown that ghrelin migrates through the bloodstream and into the brain, where it stimulates receptors on nerve cells in the h:,Dothalamus. This structure, found at the base of the brain, subsequently triggers appetite.

Researchers have also found ghrelin receptors scattered throughout the brain beyond the hypothalamus. "The question was, 'What is ghrelin doing in the rest of the brain, if anything?'" says Tamas Horvath, a neuroscientist at Yale University School of Medicine.

Horvath and his team focused their attention on ghrelin's role in the hippocampus, a brain area involved in learning and memory and that's littered with ghrelin receptors. The scientists started by injecting some normal mice with extra ghrelin and others with an equal amount of saline over the course of several day-s. When they examined the animals' brains, they found that hippocampal cells in those mice that had received ghrelin had about a quarter more dendritic spines, which are specialized nerve cell connections associated with learning.

The scientists found a similar scenario when they compared normal mice with mice genetically altered so that they didn't make any ghrelin. The ghrelin-deficient animals had about 25 percent fewer dendritic spines than normal mice did. …

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