Tags

Type your tag names separated by a space and hit enter

Synaptic activation of N-methyl-D-aspartate receptors in the Schaffer collateral-commissural pathway of rat hippocampus.
J Physiol. 1988 May; 399:283-300.JP

Abstract

1. The involvement of N-methyl-D-aspartate (NMDA) receptors in the response to single-shock (0.033 Hz) stimulation of the Schaffer collateral-commissural pathway in hippocampal slices has been investigated using current- and voltage-clamp techniques. 2. In the presence of Mg2+ (1 or 2 mM) at membrane potentials near rest, the selective NMDA antagonist D-2-amino-5-phosphonovalerate (APV) had no effect on the excitatory postsynaptic potential (EPSP) and the biphasic inhibitory postsynaptic potential (IPSP) evoked by Schaffer collateral-commissural stimulation. The recurrent IPSP evoked by antidromic stimulation of alvear fibres was also unaffected by APV. 3. The introduction of a Mg2+-free perfusate led, at high stimulus intensity, to an orthodromically evoked epileptiform discharge but little change in the recurrent IPSP. APV suppressed a large proportion of the enhanced response in Mg2+-free perfusate. 4. EPSPs and excitatory postsynaptic currents (EPSCs) evoked in Mg2+-free perfusate invariably had both APV-resistant and APV-sensitive components. Both synaptic components had similar thresholds and latencies to onset. The APV-sensitive component had a long time to peak and long duration. 5. Under current-clamp conditions in Mg2+-containing medium, an APV-sensitive component was recorded at membrane potentials of between -30 and -10 mV, but not at potentials more negative than -55 mV. 6. Under voltage-clamp, but not current-clamp, conditions in Mg2+-containing medium, a small APV-sensitive component was recorded at resting membrane potentials and increased with membrane depolarization. The difference between the current- and voltage-clamp data is attributed to the hyperpolarizing influence of conjointly activated IPSPs. 7. In the presence of Mg2+ and picrotoxin, a dual-component EPSC was recorded between -30 and +30 mV in all cells examined. The APV-resistant and APV-sensitive components had similar latencies to onset. They both had reversal potentials of between -8 and 0 mV. The APV-sensitive component had a longer latency to peak and duration than the APV-resistant component. 8. It is suggested that NMDA receptors can contribute a low-threshold and long-duration monosynaptic component of the response evoked by low-frequency stimulation of the Schaffer collateral-commissural pathway. However, under physiological conditions significant expression of this component is prevented by concurrently activated IPSPs which rapidly hyperpolarize neurones into a region where Mg2+ substantially blocks NMDA channels.

Authors+Show Affiliations

Department of Pharmacology, University of Bristol, Medical School.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

2900332

Citation

Collingridge, G L., et al. "Synaptic Activation of N-methyl-D-aspartate Receptors in the Schaffer Collateral-commissural Pathway of Rat Hippocampus." The Journal of Physiology, vol. 399, 1988, pp. 283-300.
Collingridge GL, Herron CE, Lester RA. Synaptic activation of N-methyl-D-aspartate receptors in the Schaffer collateral-commissural pathway of rat hippocampus. J Physiol. 1988;399:283-300.
Collingridge, G. L., Herron, C. E., & Lester, R. A. (1988). Synaptic activation of N-methyl-D-aspartate receptors in the Schaffer collateral-commissural pathway of rat hippocampus. The Journal of Physiology, 399, 283-300.
Collingridge GL, Herron CE, Lester RA. Synaptic Activation of N-methyl-D-aspartate Receptors in the Schaffer Collateral-commissural Pathway of Rat Hippocampus. J Physiol. 1988;399:283-300. PubMed PMID: 2900332.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Synaptic activation of N-methyl-D-aspartate receptors in the Schaffer collateral-commissural pathway of rat hippocampus. AU - Collingridge,G L, AU - Herron,C E, AU - Lester,R A, PY - 1988/5/1/pubmed PY - 1988/5/1/medline PY - 1988/5/1/entrez SP - 283 EP - 300 JF - The Journal of physiology JO - J Physiol VL - 399 N2 - 1. The involvement of N-methyl-D-aspartate (NMDA) receptors in the response to single-shock (0.033 Hz) stimulation of the Schaffer collateral-commissural pathway in hippocampal slices has been investigated using current- and voltage-clamp techniques. 2. In the presence of Mg2+ (1 or 2 mM) at membrane potentials near rest, the selective NMDA antagonist D-2-amino-5-phosphonovalerate (APV) had no effect on the excitatory postsynaptic potential (EPSP) and the biphasic inhibitory postsynaptic potential (IPSP) evoked by Schaffer collateral-commissural stimulation. The recurrent IPSP evoked by antidromic stimulation of alvear fibres was also unaffected by APV. 3. The introduction of a Mg2+-free perfusate led, at high stimulus intensity, to an orthodromically evoked epileptiform discharge but little change in the recurrent IPSP. APV suppressed a large proportion of the enhanced response in Mg2+-free perfusate. 4. EPSPs and excitatory postsynaptic currents (EPSCs) evoked in Mg2+-free perfusate invariably had both APV-resistant and APV-sensitive components. Both synaptic components had similar thresholds and latencies to onset. The APV-sensitive component had a long time to peak and long duration. 5. Under current-clamp conditions in Mg2+-containing medium, an APV-sensitive component was recorded at membrane potentials of between -30 and -10 mV, but not at potentials more negative than -55 mV. 6. Under voltage-clamp, but not current-clamp, conditions in Mg2+-containing medium, a small APV-sensitive component was recorded at resting membrane potentials and increased with membrane depolarization. The difference between the current- and voltage-clamp data is attributed to the hyperpolarizing influence of conjointly activated IPSPs. 7. In the presence of Mg2+ and picrotoxin, a dual-component EPSC was recorded between -30 and +30 mV in all cells examined. The APV-resistant and APV-sensitive components had similar latencies to onset. They both had reversal potentials of between -8 and 0 mV. The APV-sensitive component had a longer latency to peak and duration than the APV-resistant component. 8. It is suggested that NMDA receptors can contribute a low-threshold and long-duration monosynaptic component of the response evoked by low-frequency stimulation of the Schaffer collateral-commissural pathway. However, under physiological conditions significant expression of this component is prevented by concurrently activated IPSPs which rapidly hyperpolarize neurones into a region where Mg2+ substantially blocks NMDA channels. SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/2900332/Synaptic_activation_of_N_methyl_D_aspartate_receptors_in_the_Schaffer_collateral_commissural_pathway_of_rat_hippocampus_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0022-3751&date=1988&volume=399&spage=283 DB - PRIME DP - Unbound Medicine ER -