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Physiological Functions of Glial Cell Hemichannels

  • Juan A. OrellanaEmail author
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 949)

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.

Keywords

Connexins Pannexins (ATP) adenosine triphosphate Astroglial signaling Gliotransmitters 

Abbreviations and acronyms

Arc

Arcuate

ATP

Adenosine triphosphate

BLA

Basolateral amygdala

[Ca2+]i

Intracellular free Ca2+ concentration

CSF

Cerebrospinal fluid

CNS

Central nervous system

Cx26

Connexin26

Cx36

Connexin36

Cx43

Connexin43

GFAP

Glial fibrillary acidic protein

GJCs

Gap junction channels

kDa

Kilodalton

KO

Knockout

NAD+

Nicotinamide adenine dinucleotide

NMDA

N-methyl-D-aspartate

MAP2

Microtubule-associated protein 2

MBH

Mediobasal hypothalamus

MI

Metabolic inhibition

Panx1

Pannexin1

Panx2

Pannexin2

PGE2

Prostaglandin E2

RTN

Retrotrapezoid nucleus

siRNA

Small interfering ribonucleic acid

VMH

Ventromedial hypothalamic nuclei

VMS

Ventral medullary surface

TDCS

Transcranial direct current stimulation

Notes

Acknowledgments

This work was partially supported by the Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT) Grant 11121133 (to JAO), 1160710 (to JAO), the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) and Programa de Investigación Asociativa (PIA) Grant Anillo de Ciencia y Tecnología ACT1411 (to JAO). We apologize to the authors and groups whose work we did not cite due to space limitations.

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© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Departamento de Neurología, Escuela de MedicinaPontificia Universidad Católica de ChileSantiagoChile

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