Local Efficacy of Glutamate Uptake Decreases with Synapse Size

Autor: Michel K. Herde, Kirsten Bohmbach, Cátia Domingos, Natascha Vana, Joanna A. Komorowska-Müller, Stefan Passlick, Inna Schwarz, Colin J. Jackson, Dirk Dietrich, Martin K. Schwarz, Christian Henneberger
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Cell Reports, Vol 32, Iss 12, Pp 108182- (2020)
Druh dokumentu: article
ISSN: 2211-1247
DOI: 10.1016/j.celrep.2020.108182
Popis: Summary: Synaptically released glutamate is largely cleared by glutamate transporters localized on perisynaptic astrocyte processes. Therefore, the substantial variability of astrocyte coverage of individual hippocampal synapses implies that the efficacy of local glutamate uptake and thus the spatial fidelity of synaptic transmission is synapse dependent. By visualization of sub-diffraction-limit perisynaptic astrocytic processes and adjacent postsynaptic spines, we show that, relative to their size, small spines display a stronger coverage by astroglial transporters than bigger neighboring spines. Similarly, glutamate transients evoked by synaptic stimulation are more sensitive to pharmacological inhibition of glutamate uptake at smaller spines, whose high-affinity N-methyl-D-aspartate receptors (NMDARs) are better shielded from remotely released glutamate. At small spines, glutamate-induced and NMDAR-dependent Ca2+ entry is also more strongly increased by uptake inhibition. These findings indicate that spine size inversely correlates with the efficacy of local glutamate uptake and thereby likely determines the probability of synaptic crosstalk.
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