N-METHYL-D-ASPARTATE RECEPTORS CONTRIBUTE TO EXCITATORY POSTSYNAPTIC POTENTIALS OF CAT LATERAL GENICULATE NEURONS RECORDED IN THALAMIC SLICES

被引:147
作者
SCHARFMAN, HE [1 ]
LU, SM [1 ]
GUIDO, W [1 ]
ADAMS, PR [1 ]
SHERMAN, SM [1 ]
机构
[1] SUNY STONY BROOK,DEPT NEUROBIOL & BEHAV,STONY BROOK,NY 11794
关键词
corticogeniculate; excitatory amino acid; low-threshold calcium spike; optic tract; retinogeniculate;
D O I
10.1073/pnas.87.12.4548
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Neurons of the cat's dorsal lateral geniculate nucleus were recorded intracellularly to study the contribution of N-methyl-D-aspartate (NMDA) receptors to excitatory postsynaptic potentials (EPSPs) and low-threshold calcium spikes. EPSPs were evoked by stimulation of retinogeniculate axons in the optic tract and/or corticogeniculate axons in the optic radiations; EPSPs from both sources were similar. These EPSPs had one or two components, and the second component had several characteristics of NMDA receptor-mediated events. For example, EPSP amplitude decreased when neurons were hyperpolarized and increased when stimulus frequency was increased; these EPSPs could also be blocked reversibly by application of the selective NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV). We also studied the influence of NMDA receptors on low-threshold calcium spikes, which are large, voltage- and calcium-dependent depolarizations that are often accompanied by high-frequency action potential discharge. APV blocked synaptically activated low-threshold calcium spikes, but APV had no effect on low-threshold calcium spikes that were elicited by current injection. Therefore, APV does not appear to have a direct effect on the T-type calcium channel that is involved in generation of low-threshold calcium spikes. The voltage and frequency dependence of the NMDA receptor-mediated component of the EPSPs, as well as its ability to trigger low-threshold calcium spikes, provide for complex signal processing in the lateral geniculate nucleus.
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页码:4548 / 4552
页数:5
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