ROLE OF INSULIN IN BRAIN: DELVE INTO THE MOLECULAR MECHANISMS

We have learned over the last several decades that the brain is an important target for insulin action. In central nervous system (CNS) it mainly affects feeding behaviour and various aspects of memory and cognition. Insulin signalling in CNS has emerged as a novel field of research since decreases brain insulin levels and signalling were associated to impaired learning, memory and age-related neurodegenerative diseases. Alterations of these functional activities may contribute to the manifestation of several clinical entities, such as central insulin resistance, type 2 diabetes mellitus (T2DM) and Alzheimer’s disease (AD). A close alliance between T2DM and AD has been reported, to the extent that AD is twice more frequent in diabetic patients. There are links between T2DM and AD through mitochondrial alterations and oxidative stress, altered energy and glucose metabolism, cholesterol modifications, dysfunctional protein O-GlcNAcylation, formation of amyloid plaques, altered Aβ metabolism and tau hyperphosphorylation. Herewith, we aim to integrate the metabolic, neuromodulatory, and neuroprotective roles of insulin in two age-related pathologies: T2DM and AD, both in terms of intracellular signalling and potential therapeutic approach.