Scientists Link 'Hunger Hormone' to Memory in Alzheimer's Study

A study in Science Translational Medicine suggests that resistance to the "hunger hormone" ghrelin in the brain is associated with cognitive impairments and memory loss linked to Alzheimer's disease, reports Medical Xpress . The stomach generates ghrelin, which transmits signals to the brain that regulate energy balance and body weight. In a healthy hippocampus, ghrelin binds with ghrelin receptors, which mix with similarly activated receptors for the neurotransmitter dopamine, then form a protein complex that helps maintain interaction between neurons and memory. Amyloid beta was found to bind ghrelin receptors in the hippocampus, impeding their combination into dopamine receptors. "As the brain loses the function of ghrelin receptors due to amyloid beta, the body tries to compensate by increasing the production of ghrelin and the number of ghrelin receptors," said University of Texas at Dallas Professor Heng Du. "But the amyloid prevents the receptors from functioning." The researchers administered the ghrelin receptor-activating compound MK0677 and the dopamine receptor-activating SKF81297 compound in mice with Alzheimer's. Concurrent administration improved cognition and memory, suggesting a possible treatment.