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Comparing long-term depression with pharmacologically induced synaptic attenuations in young rat hippocampi.
Synapse. 1997 Aug; 26(4):329-40.S

Abstract

Field excitatory postsynaptic potentials (EPSPs) were recorded in the CA1 region of hippocampal slices from 12-18-day-old rats. The isolated N-methyl-D-aspartate (NMDA) receptor mediated field EPSP as well as the composite field EPSP of both NMDA and alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) receptor mediated components were obtained in low Mg2+ solutions with 10 microM or 1 microM of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), respectively. The isolated AMPA receptor mediated field EPSP was obtained either in normal Mg2+ solution or in a low Mg2+ solution in the presence of the NMDA receptor antagonist D-2-amino-5-phosphonopentanoic acid. The waveforms of the field EPSPs were studied and the effect of long-term depression (LTD) on these waveforms was compared with the effects of several pharmacological agents that attenuate the synaptic efficacy. It was shown that LTD occurred without changes in the waveforms of isolated AMPA and NMDA EPSPs. Reducing the number of release sites by lowering the stimulus strength or reducing the probability of transmitter release by an adenosine agonist N6-cyclohexyl-adenosine both mimicked the LTD-induced changes. Partial blockade of the AMPA receptors was also without effect on the waveforms of isolated AMPA EPSPs. In contrast, partial blockade of the NMDA receptors in several different ways resulted in waveform changes. A similar result could be inferred from experiments using composite field EPSPs. The synaptic attenuation caused by a partial blockade of NMDA receptors therefore appears to differ mechanistically from that involved in LTD, arguing against a postsynaptic locus of the modification involved in LTD. However, directly testing for alterations in transmitter release using the open channel blocker of NMDA receptors MK-801 failed in revealing such presynaptic changes during LTD. Our results therefore suggest that LTD might be due to a coordinated pre- and postsynaptic change instead of distinct pre- or postsynaptic modifications.

Authors+Show Affiliations

Department of Medical Biophysics, Goteborg University, Sweden. xiao@mednet.gu.seNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

9215592

Citation

Xiao, M Y., et al. "Comparing Long-term Depression With Pharmacologically Induced Synaptic Attenuations in Young Rat Hippocampi." Synapse (New York, N.Y.), vol. 26, no. 4, 1997, pp. 329-40.
Xiao MY, Niu YP, Wigstrom H. Comparing long-term depression with pharmacologically induced synaptic attenuations in young rat hippocampi. Synapse. 1997;26(4):329-40.
Xiao, M. Y., Niu, Y. P., & Wigstrom, H. (1997). Comparing long-term depression with pharmacologically induced synaptic attenuations in young rat hippocampi. Synapse (New York, N.Y.), 26(4), 329-40.
Xiao MY, Niu YP, Wigstrom H. Comparing Long-term Depression With Pharmacologically Induced Synaptic Attenuations in Young Rat Hippocampi. Synapse. 1997;26(4):329-40. PubMed PMID: 9215592.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Comparing long-term depression with pharmacologically induced synaptic attenuations in young rat hippocampi. AU - Xiao,M Y, AU - Niu,Y P, AU - Wigstrom,H, PY - 1997/8/1/pubmed PY - 2000/6/20/medline PY - 1997/8/1/entrez SP - 329 EP - 40 JF - Synapse (New York, N.Y.) JO - Synapse VL - 26 IS - 4 N2 - Field excitatory postsynaptic potentials (EPSPs) were recorded in the CA1 region of hippocampal slices from 12-18-day-old rats. The isolated N-methyl-D-aspartate (NMDA) receptor mediated field EPSP as well as the composite field EPSP of both NMDA and alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) receptor mediated components were obtained in low Mg2+ solutions with 10 microM or 1 microM of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), respectively. The isolated AMPA receptor mediated field EPSP was obtained either in normal Mg2+ solution or in a low Mg2+ solution in the presence of the NMDA receptor antagonist D-2-amino-5-phosphonopentanoic acid. The waveforms of the field EPSPs were studied and the effect of long-term depression (LTD) on these waveforms was compared with the effects of several pharmacological agents that attenuate the synaptic efficacy. It was shown that LTD occurred without changes in the waveforms of isolated AMPA and NMDA EPSPs. Reducing the number of release sites by lowering the stimulus strength or reducing the probability of transmitter release by an adenosine agonist N6-cyclohexyl-adenosine both mimicked the LTD-induced changes. Partial blockade of the AMPA receptors was also without effect on the waveforms of isolated AMPA EPSPs. In contrast, partial blockade of the NMDA receptors in several different ways resulted in waveform changes. A similar result could be inferred from experiments using composite field EPSPs. The synaptic attenuation caused by a partial blockade of NMDA receptors therefore appears to differ mechanistically from that involved in LTD, arguing against a postsynaptic locus of the modification involved in LTD. However, directly testing for alterations in transmitter release using the open channel blocker of NMDA receptors MK-801 failed in revealing such presynaptic changes during LTD. Our results therefore suggest that LTD might be due to a coordinated pre- and postsynaptic change instead of distinct pre- or postsynaptic modifications. SN - 0887-4476 UR - https://www.unboundmedicine.com/medline/citation/9215592/Comparing_long_term_depression_with_pharmacologically_induced_synaptic_attenuations_in_young_rat_hippocampi_ L2 - https://doi.org/10.1002/(SICI)1098-2396(199708)26:4<329::AID-SYN1>3.0.CO;2-8 DB - PRIME DP - Unbound Medicine ER -