0000000000628242
AUTHOR
Olga Myakhar
Estimation of ambient GABA levels in layer I of the mouse neonatal cortex in brain slices
GABAergic synapses on Cajal–Retzius neurons in layer I of the murine neocortex experience GABAB receptor (GABABR)-mediated tonic inhibition. Extracellular GABA concentration ([GABA]o) that determines the strength of GABABR-mediated inhibition is controlled by GABA transporters (GATs). In this study, we hypothesized that the strength ofpresynaptic GABABR activation reflects [GABA]o in the vicinity of synaptic contacts. Slices obtained from two age groups were used, namely postnatal days (P)2–3 and P5–7. GABAergic postsynaptic currents (IPSCs) were recorded using the whole-cell patch-clamp technique. Minimal electrical stimulation in layer I was applied to elicit evoked IPSCs (eIPSCs) using a…
GABAergic projections from the subplate to Cajal-Retzius cells in the neocortex.
Subplate neurons and Cajal-Retzius cells play an important role in the corticogenesis. Despite morphological evidence, the question whether subplate neurons innervate Cajal-Retzius cells has not been studied yet. We report that electrical stimulation in the subplate resulted in evoked GABAergic inhibitory postsynaptic currents (eIPSCs) in Cajal-Retzius cells. The eIPSC latency showed minor variability and amounted to approximately 4 ms, suggesting the monosynaptic connection. During the first postnatal week: (i) eIPSC amplitude increased, (ii) eIPSC kinetics sped up, (iii) the size of readily releasable pool increased, and (iv) γ-aminobutyric acid release probability decreased. We conclude …
Intracellular Na+ concentration influences short-term plasticity of glutamate transporter-mediated currents in neocortical astrocytes.
Fast synaptic transmission requires a rapid clearance of the released neurotransmitter from the extracellular space. Glial glutamate transporters (excitatory amino acid transporters, EAATs) strongly contribute to glutamate removal. In this work, we investigated the paired-pulse plasticity of synaptically activated, glutamate transporter-mediated currents (STCs) in cortical layer 2/3 astrocytes. STCs were elicited by local electrical stimulation in layer 4 in the presence of ionotropic glutamate (AMPA and NMDA), GABAA, and GABAB receptor antagonists. In experiments with low [Na+]i (5 mM) intrapipette solution, STCs elicited by paired-pulse stimulation demonstrated paired-pulse facilitation (…