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Differential sensitivity of medium‐ and large‐sized striatal neurons to NMDA but not kainate receptor activation in the rat
Author(s) -
Cepeda Carlos,
Itri Jason N.,
FloresHernández Jorge,
Hurst Raymond S.,
Calvert Christopher R.,
Levine Michael S.
Publication year - 2001
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.0953-816x.2001.01783.x
Subject(s) - kainate receptor , nmda receptor , excitatory postsynaptic potential , neuroscience , postsynaptic potential , cnqx , biophysics , postsynaptic current , differential interference contrast microscopy , glutamate receptor , medium spiny neuron , patch clamp , depolarization , stimulation , chemistry , biology , inhibitory postsynaptic potential , electrophysiology , receptor , ampa receptor , central nervous system , biochemistry , medicine , basal ganglia , microscopy , pathology
Infrared videomicroscopy and differential interference contrast optics were used to identify medium‐ and large‐sized neurons in striatal slices from young rats. Whole‐cell patch‐clamp recordings were obtained to compare membrane currents evoked by application of N ‐methyl‐ d ‐aspartate (NMDA) and kainate. Inward currents and current densities induced by NMDA were significantly smaller in large‐ than in medium‐sized striatal neurons. The negative slope conductance for NMDA currents was greater in medium‐ than in large‐sized neurons and more depolarization was required to remove the Mg 2+ blockade. In contrast, currents induced by kainate were significantly greater in large‐sized neurons whilst current densities were approximately equal in both cell types. Spontaneous excitatory postsynaptic currents occurred frequently in medium‐sized neurons but were relatively infrequent in large‐sized neurons. Excitatory postsynaptic currents evoked by electrical stimulation were smaller in large‐ than in medium‐sized neurons. A final set of experiments assessed a functional consequence of the differential sensitivity of medium‐ and large‐sized neurons to NMDA. Cell swelling was used to examine changes in somatic area in both neuronal types after prolonged application of NMDA or kainate. NMDA produced a time‐dependent increase in somatic area in medium‐sized neurons whilst it produced only minimal changes in large interneurons. In contrast, application of kainate produced significant swelling in both medium‐ and large‐sized cells. We hypothesize that reduced sensitivity to NMDA may be due to variations in receptor subunit composition and/or the relative density of receptors in the two cell types. These findings help define the conditions that put neurons at risk for excitotoxic damage in neurological disorders.