The Journal of Neuroscience, July 1, 2000, 20(13):4844-4854
Unique Properties of NMDA Receptors Enhance Synaptic Excitation
of Radiatum Giant Cells in Rat Hippocampus
Eilon D.
Kirson and
Yoel
Yaari
Department of Physiology, Institute of Medical Sciences, The Hebrew
University-Hadassah Faculty of Medicine, Jerusalem 91120, Israel
In the hippocampus, fast excitatory synaptic transmission of
principal projection neurons is mediated by non-NMDA glutamate receptors, whereas NMDA glutamate receptors serve a slower modulatory role. We used the whole-cell patch-clamp technique in adult hippocampal slices to assess the role of NMDA receptors in synaptic excitation of a
recently discovered excitatory projection neuron, the CA1 radiatum
giant cell (RGC). Glutamatergic synaptic activation, even after
blocking non-NMDA receptors, fired an NMDA receptor-dependent burst of
action potentials in RGCs. In contrast, the contribution of NMDA
receptors to synaptic activation of pyramidal cells (PCs) was minimal.
Stimulation of the same synaptic inputs evoked greater than threefold
larger EPSCs in RGCs than in PCs. Isolated NMDA receptor-mediated EPSCs
were significantly less sensitive to blockade by extracellular
Mg2+ and had slower decay kinetics in RGCs than in
PCs. Thus, unique properties of synaptic NMDA receptors underlie
enhanced synaptic excitability in a newly discovered excitatory
hippocampal projection neuron.
Key words:
radiatum giant cell; NMDA; magnesium sensitivity; EPSC; hippocampus; rat
Copyright © 2000 Society for Neuroscience 0270-6474/00/20134844-11$05.00/0