Role of connexins and pannexins in ischemic stroke

Abstract

Synaptic plasticity requires careful synchronization and coordination of neurons and glial cells via various mechanisms of intercellular communication. Among them, are those mediated by i) connexin gap junction channels (GJCs), ii) connexin hemichannels and iii) pannexin channels. Whereas GJCs directly communicate the cytoplasm of contacting cells and coordinate electric and metabolic activities, connexin hemichannels and pannexin channels serve as diffusional pathways for ions and small molecules between the intra- and extracellular compartments. A growing body of evidence has revealed that intercellular communication could be critical in the spread of protective and/or deleterious signals during stroke. Here, we review current findings on the regulation of connexin- and pannexin-based channels in ischemic stroke and how they contribute to cell damage observed in pathology. Depending on intensity of the ischemic event, brain region and connexin subtype expressed, GJCs may provide proper diffusion of energy metabolites and dissipation of toxic substances, whereas, in other circumstances, they could increase damage by spreading toxic molecules. Alternatively, connexin hemichannel and pannexin channel opening may favor the release of neurotoxic substances (e.g., glutamate), but in other cases, they may confer neuroprotection against an ischemic episode by the phenomenon of ischemic preconditioning. Development of new drug modulators using in silico devices for connexin and pannexin-based channels will be crucial for future therapies against stroke.