Local Efficacy of Glutamate Uptake Decreases with Synapse Size

Cell Reports

Dirk Dietrich¹  Natascha Vana¹  Kirsten Bohmbach²  Christian Henneberger²  Cátia Domingos²  Michel K. Herde²  Stefan Passlick²  Joanna A. Komorowska-Müller²  Inna Schwarz³  Martin K. Schwarz³  Colin J. Jackson⁴ 

[1] Department for Neurosurgery, University Hospital Bonn, Bonn, Germany;Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany;Institute of Epileptology, Medical Faculty, University of Bonn, Bonn, Germany;Research School of Chemistry, Australian National University, Canberra, Australia;

关键词: glutamate uptake;    astrocytes;    hippocampus;    astrocyte morphology;    spine morphology;    multiphoton imaging;   

DOI  :  

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown