Chapter 14 - Gap Junction-Mediated Neuroprotection

Abstract

Gap junctions are intercellular channels which provide communication pathways in the central nervous system (CNS). In addition to electrical synapses between neurons, the majority of gap junctions are present in the non-neuronal compartment of the CNS: the glial cells (astrocytes, oligodendrocytes, microglia) and endothelial cells. One view of the role of astrocytic gap junctions has been to provide a mechanism by which the extracellular environment of neurons can be carefully regulated, or buffered. This has been proposed to provide neuroprotection under excitotoxic or ischemic conditions. While there is significant support for such a neuroprotective role of gap junctions, there are equally compelling data that gap junctions actually increase neuronal injury under such conditions. In reviewing both aspects of gap junctions in neuroprotection, it is clear that the context of the system being studied is important to appreciate the role that these channels and their connexin proteins play in cellular events.