Abstract
The activation of the N-methyl D-aspartate receptor (NMDAR) is controlled by a glutamate-binding site and a distinct, independently regulated, co-agonist-binding site. In most brain regions, the NMDAR co-agonist is the astrocyte-derived gliotransmitter D-serine. We found that D-serine levels oscillate in mouse hippocampus as a function of wakefulness, in vitro and in vivo. This causes a full saturation of the NMDAR co-agonist site in the dark (active) phase that dissipates to sub-saturating levels during the light (sleep) phase, and influences learning performance throughout the day. We demonstrate that hippocampal astrocytes sense the wakefulness-dependent activity of septal cholinergic fibers through the α7-nicotinic acetylcholine receptor (α7nAChR), whose activation drives D-serine release. We conclude that astrocytes tune the gating of synaptic NMDARs to the vigilance state and demonstrate that this is directly relevant to schizophrenia, a disorder characterized by NMDAR and cholinergic hypofunctions. Indeed, bypassing cholinergic activity with a clinically tested α7nAChR agonist successfully enhances NMDAR activation.
Original language | English |
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Pages (from-to) | 840-854.e7 |
Journal | Neuron |
Volume | 94 |
Issue number | 4 |
DOIs | |
State | Published - May 17 2017 |
Keywords
- D-serine
- EVP-6124
- NMDAR
- acetylcholine
- astrocytes
- contextual guidance
- schizophrenia
- vigilance state
- wakefulness
- α7nAChR