Referenced in: none

Automatically associated channels: TRP , TRPV , TRPV4

Title: A novel subtype of astrocytes expressing TRPV4 (transient receptor potential vanilloid 4) regulates neuronal excitability via release of gliotransmitters.

Authors: Koji Shibasaki, Kazuhiro Ikenaka, Fuminobu Tamalu, Makoto Tominaga, Yasuki Ishizaki

Journal, date & volume: J. Biol. Chem., 2014 May 23 , 289, 14470-80

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24737318

Abstract
Astrocytes play active roles in the regulation of synaptic transmission. Neuronal excitation can evoke Ca(2+) transients in astrocytes, and these Ca(2+) transients can modulate neuronal excitability. Although only a subset of astrocytes appears to communicate with neurons, the types of astrocytes that can regulate neuronal excitability are poorly characterized. We found that ∼30% of astrocytes in the brain express transient receptor potential vanilloid 4 (TRPV4), indicating that astrocytic subtypes can be classified on the basis of their expression patterns. When TRPV4(+) astrocytes are activated by ligands such as arachidonic acid, the activation propagates to neighboring astrocytes through gap junctions and by ATP release from the TRPV4(+) astrocytes. After activation, both TRPV4(+) and TRPV4(-) astrocytes release glutamate, which acts as an excitatory gliotransmitter to increase synaptic transmission through type 1 metabotropic glutamate receptor (mGluR). Our results indicate that TRPV4(+) astrocytes constitute a novel subtype of the population and are solely responsible for initiating excitatory gliotransmitter release to enhance synaptic transmission. We propose that TRPV4(+) astrocytes form a core of excitatory glial assembly in the brain and function to efficiently increase neuronal excitation in response to endogenous TRPV4 ligands.