WASHINGTON, June 14 (UPI) -- The hormone leptin, which is secreted by fat cells and tells us when to stop eating, also affects long-term memory and learning.
In a report released this week, researchers at the Saint Louis University School of Medicine said they were studying the connection between obesity, Type 2 diabetes, and long-term memory loss, and decided to explore the role of leptin in these processes.
"In obese people, [leptin] doesn't cross into the brain to help regulate appetite," the research team said. "We've now found leptin affects the brain in other ways, compromising learning and memory. Low levels of leptin also could be related to cognitive deficits in disorders like Type 2 diabetes."
The scientists evaluated how well mice navigated a maze, then gave some of them leptin and sent all of the animals through the maze a second time.
The mice that got the leptin navigated the maze better than those that did not receive the hormone. Older mice with amyloid-beta plaques in their brain, typical of Alzheimer's disease in humans, responded the best, and showed benefit at a lower dose than younger mice.
