ROLE OF CALCIUM IN BRAIN AGING

1. Calcium is a universal messenger of extracellular signals in a grea t variety of cells; it regulates several neuronal functions, such as n eurotransmitter synthesis and release, neuronal excitability, phosphor ylation and so on. Calcium is also involved in long-term processes, li ke memory. 2. Recent studies demonstrated that brain aging is characte rized by alterations in neuronal function due to the changes in calciu m homeostasis. This occurs for various reasons, such as changes in cal cium channels, decrease of ion binding to specific proteins and change s in the mechanisms involved in its sequestration and extrusion from n euronal cell. 3. Moreover, it has been shown that high levels of gluco corticoids are neurotoxic, because they alter calcium homeostasis on h ypothalamic neurons by increasing calcium voltage-dependent flow, espe cially in aged neurons. 4. New information about the role of calcium i n brain aging could derive from the expansion of new imaging technique s, such as positron emission tomography, single photon emission tomogr aphy and nuclear magnetic resonance, which allow in vivo quantitative measurements of functional parameters and their comparison with behavi oural data.