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Comparison of paired-pulse facilitation of AMPA and NMDA synaptic currents in the lateral amygdala.
Synapse 2001; 42(2):115-27S

Abstract

Stimulating thalamic fibers exiting from the internal capsule evokes a glutamatergic excitatory postsynaptic current (EPSC) recorded in vitro with patch electrodes in neurons of the rat lateral amygdala (LA). The purpose of this study is to compare paired-pulse facilitation (PPF), a form of short-term synaptic plasticity, of AMPA and NMDA receptor-mediated EPSCs. Analysis of PPF at this synapse is important since, in fear-conditioned animals, PPF reflects an enhanced transmitter release but the amplitude of only AMPA EPSCs is facilitated. PPF magnitude of the composite EPSC is a result of both AMPA and NMDA receptor activation; however, the characteristics of AMPA and NMDA PPF are dissimilar. Specifically, the NMDA EPSC shows greater PPF (NMDA PPF) than does the AMPA EPSC whether measuring the NMDA PPF magnitude in an AMPA antagonist/Mg(2+)-free solution or by subtracting the AMPA EPSC from the composite EPSC in normal Mg(2+). Presynaptic NMDA receptors neither influence AMPA PPF nor account for the difference between the NMDA and AMPA PPF. Another difference was that removal of inhibitory tone enhanced AMPA PPF, while it had mixed effects on NMDA PPF. Furthermore, AMPA PPF was independent of stimulus intensity and postsynaptic voltage, unlike the NMDA PPF. Another dissimilarity was that the amplitudes of pairs of AMPA EPSCs were not correlated, suggesting presynaptic mechanisms. In contrast, NMDA PPF was dependent on stimulus intensity and postsynaptic voltage and the amplitudes of paired NMDA EPSCs had a positive correlation, suggesting a postsynaptic influence. Both AMPA and NMDA PPF were influenced by GABA inhibition and this could be a factor in the magnitude disparity. These data show that AMPA and NMDA PPF have different characteristics and contribute to the composite PPF in the thalamic to lateral amygdala pathway.

Authors+Show Affiliations

Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555-1031, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11574948

Citation

Zinebi, F, et al. "Comparison of Paired-pulse Facilitation of AMPA and NMDA Synaptic Currents in the Lateral Amygdala." Synapse (New York, N.Y.), vol. 42, no. 2, 2001, pp. 115-27.
Zinebi F, Russell RT, McKernan M, et al. Comparison of paired-pulse facilitation of AMPA and NMDA synaptic currents in the lateral amygdala. Synapse. 2001;42(2):115-27.
Zinebi, F., Russell, R. T., McKernan, M., & Shinnick-Gallagher, P. (2001). Comparison of paired-pulse facilitation of AMPA and NMDA synaptic currents in the lateral amygdala. Synapse (New York, N.Y.), 42(2), pp. 115-27.
Zinebi F, et al. Comparison of Paired-pulse Facilitation of AMPA and NMDA Synaptic Currents in the Lateral Amygdala. Synapse. 2001;42(2):115-27. PubMed PMID: 11574948.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparison of paired-pulse facilitation of AMPA and NMDA synaptic currents in the lateral amygdala. AU - Zinebi,F, AU - Russell,R T, AU - McKernan,M, AU - Shinnick-Gallagher,P, PY - 2001/9/28/pubmed PY - 2002/1/5/medline PY - 2001/9/28/entrez SP - 115 EP - 27 JF - Synapse (New York, N.Y.) JO - Synapse VL - 42 IS - 2 N2 - Stimulating thalamic fibers exiting from the internal capsule evokes a glutamatergic excitatory postsynaptic current (EPSC) recorded in vitro with patch electrodes in neurons of the rat lateral amygdala (LA). The purpose of this study is to compare paired-pulse facilitation (PPF), a form of short-term synaptic plasticity, of AMPA and NMDA receptor-mediated EPSCs. Analysis of PPF at this synapse is important since, in fear-conditioned animals, PPF reflects an enhanced transmitter release but the amplitude of only AMPA EPSCs is facilitated. PPF magnitude of the composite EPSC is a result of both AMPA and NMDA receptor activation; however, the characteristics of AMPA and NMDA PPF are dissimilar. Specifically, the NMDA EPSC shows greater PPF (NMDA PPF) than does the AMPA EPSC whether measuring the NMDA PPF magnitude in an AMPA antagonist/Mg(2+)-free solution or by subtracting the AMPA EPSC from the composite EPSC in normal Mg(2+). Presynaptic NMDA receptors neither influence AMPA PPF nor account for the difference between the NMDA and AMPA PPF. Another difference was that removal of inhibitory tone enhanced AMPA PPF, while it had mixed effects on NMDA PPF. Furthermore, AMPA PPF was independent of stimulus intensity and postsynaptic voltage, unlike the NMDA PPF. Another dissimilarity was that the amplitudes of pairs of AMPA EPSCs were not correlated, suggesting presynaptic mechanisms. In contrast, NMDA PPF was dependent on stimulus intensity and postsynaptic voltage and the amplitudes of paired NMDA EPSCs had a positive correlation, suggesting a postsynaptic influence. Both AMPA and NMDA PPF were influenced by GABA inhibition and this could be a factor in the magnitude disparity. These data show that AMPA and NMDA PPF have different characteristics and contribute to the composite PPF in the thalamic to lateral amygdala pathway. SN - 0887-4476 UR - https://www.unboundmedicine.com/medline/citation/11574948/Comparison_of_paired_pulse_facilitation_of_AMPA_and_NMDA_synaptic_currents_in_the_lateral_amygdala_ DB - PRIME DP - Unbound Medicine ER -