Insulin and insulin-like growth factor receptors in the brain: Physiological and pathological aspects

The involvement of insulin, the insulin-like growth factors (IGF1, IGF2) and their receptors in central nervous system development and function has been the focus of scientific interest for more than 30 years. The insulin-like peptides, both locally-produced proteins as well as those transported from the circulation into the brain via the blood-brain barrier, are involved in a myriad of biological activities. These actions include, among others, neuronal survival, neurogenes, angiogenesis, excitatory and inhibitory neurotransmission, regulation of food intake, and cognition. In recent years, a linkage between brain insulin/ IGF1 and certain neuropathologies has been identified. Epidemiological studies have demonstrated a correlation between diabetes (mainly type 2) and Alzheimer's disease. In addition, an aberrant decline in IGF1 values was suggested to play a role in the development of Alzheimer's disease. The present review focuses on the expression and function of insulin, IGFs and their receptors in the brain in physiological and pathological conditions. (C) 2014 Elsevier B.V. and ECNR This is an open access article under the CC BY-NC-ND license (http://creativecommons,org/licenses/by-nc-nd/3,0/).