title: Physiological Functions of Glial Cell Hemichannels.
abstract: The brain performs exceptionally complex and dynamic tasks that depend on the coordinated interaction of neurons, glial cells, endothelial cells, pericytes, smooth muscle cells, ependymal cells, and circulating blood cells. Among these cells, glial cells have emerged as crucial protagonists in the regulation of synaptic transmission and neural function. Indeed, these cells express a wide range of receptors that enable them to sense changes in neuronal activity and the microenvironment by responding locally via the release of bioactive molecules known as gliotransmitters. In the central nervous system (CNS), a novel mechanism that allows gliotransmission via the opening of hemichannels has been proposed. These channels are composed of six protein subunits consisting of connexins or pannexins, which are two highly conserved protein families that are encoded by 21 and 3 genes, respectively, in humans. Typically, glial cell hemichannels exhibit low levels of activity, but this activity is sufficient to ensure the release of a broad spectrum of gliotransmitters, including ATP, D-serine, glutamate, adenosine, and glutathione. Here, we briefly review the current findings regarding the effects of the hemichannel-dependent release of gliotransmitters on the physiology of the CNS.
authors.affiliation: Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta #391, Santiago, Chile. jaorella@uc.cl.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Orellana
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000502:physiology; D002490:Central Nervous System / Q000166:cytology / Q000502:physiology*; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D017629:Gap Junctions / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology; D018377:Neurotransmitter Agents / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D018031:Connexin 43; D017630:Connexins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; C492764:PANX1 protein, human; D020033:Protein Isoforms; D058486:Receptors, Purinergic P2X7
keywords: (ATP) adenosine triphosphate; Astroglial signaling; Connexins; Gliotransmitters; Pannexins