Insulin and the blood-brain barrier.

Although several possible mechanisms exist by which the pancreatic hormone, insulin, could enter the brain from the blood, most evidence suggests that the majority of it enters primarily by a receptor-mediated transport process. Many factors influence the rate of entry, including fasting and refeeding and several pathological conditions. Within the brain insulin acts on specific receptors to influence a number of behaviors, and especially caloric homeostasis and cognition.