Chapter 5 - Adrenergic Ca2+ and cAMP Excitability: Effects on Glucose Availability and Cell Morphology in Astrocytes

Abstract

A number of recent studies revealed that astrocytes are a target of the locus coeruleus (LC)-nerve terminals that supply noradrenaline (NA) throughout the central nervous system (CNS). LC activation triggers a global CNS excitation, associated with arousal, which affects many processes including metabolism and memory formation. Although electrically silent, astrocytes can respond to NA via G-protein coupled membrane receptors with increased levels in cytosolic second messengers Ca2+ and cyclic adenosine monophosphate (cAMP), termed cytoplasmic excitability. Here we overview the temporal characteristics of the adrenergic Ca2+ and cAMP excitability and the mechanisms that synergize these two pathways to generate the optimal cellular and global CNS response to LC activation. Moreover, we also consider how adrenergic excitability in astrocytes regulates glucose availability, cellular morphology and prevents cytotoxic brain edema. Understanding the dynamics and molecular mechanisms underlying astrocyte noradrenergic signaling processes is of key importance to develop new therapies for neurological diseases.