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July 10, 2019 – 18:41 AMT
PanARMENIAN.Net – A team of neuroscientists from the University of Southern California has identified a surprising new role for the "hunger hormone" ghrelin. Ghrelin has already been recognized for its unique role in sending hunger signals from the digestive tract to the brain, but, as presented this week at the Society's annual meeting for the study of ingested behavior, these new findings suggest that it could also be important for memory control, reports Science Daily.
Ghrelin is produced in the stomach and secreted in preparation for food, and is known for its role in increasing hunger. "For example, ghrelin levels would be high if you were in a restaurant and looked forward to a delicious dinner that would be served soon," said Dr. Elizabeth Davis, lead author of the study. Once it is secreted, ghrelin binds to specialized receptors of the vagus nerve – a nerve that transmits a variety of signals from the intestine to the brain. "We recently discovered that in addition to influencing the amount of food consumed during a meal, the vagus nerve also influenced memory," said Dr. Scott Kanoski, lead author of the # 39; study. The team has hypothesized that ghrelin is a key molecule that helps the vagus nerve to promote memory.
Using an approach called RNA interference to reduce the amount of ghrelin receptor, the researchers blocked the signaling of ghrelin in the vagus nerve of laboratory rats. When a series of memory tasks were badigned, animals with reduced vagal ghrelin signaling were disrupted during an episodic memory test, a type of memory that involved remembering what, when, and where happened, for example the reminder of your first day of school. For rats, this involved recalling a specific object to a specific place.
The team also examined whether vagal ghrelin signaling affected feeding behavior. They found that when the vagus nerve could not receive the ghrelin signal, the animals ate more often, but consumed smaller amounts at each meal. Dr. Davis believes that these findings may be related to episodic memory problems. "The decision to eat or not to eat is influenced by the memory of the previous meal," said Davis. "Ghrelin signaling to the vagus nerve may be a molecular link shared between the memory of a past meal and the hunger signals generated in anticipation of the next meal."
These new discoveries add to our understanding of how episodic memories are generated, as well as the relationship between memory and eating behavior. In the future, researchers may be able to develop strategies to improve memory capacity in humans by manipulating the signaling of ghrelin from the intestine to the brain.
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