Insulin and insulin-receptor signaling in the brain

Modern data on the specific regulatory functions of insulin-receptor signaling in the brain is reviewed. Insulin, indistinguishable from its pancreatic form, and typical insulin receptors are widely expressed in various compartments of the brain. Insulin penetrates into the brain by means of receptor-dependent transport across the blood-brain barrier and participates in the regulation of energy homeostasis and the reproductive and cognitive functions of an organism. In the last decade convincing evidence has been provided that brain insulin and insulin-receptor signaling are necessary for the normal functioning of neurons, although the neuronal effects of insulin remain rather disputable. Any disorganization of this system provokes neurodegenerative diseases.