Modulation of synaptic transmission and long-term potentiation: effects on paired pulse facilitation and EPSC variance in the CA1 region of the hippocampus

Modulation of synaptic transmission and long-term potentiation: effects on paired pulse... Abstract 1. Whole-cell patch-clamp recordings of excitatory postsynaptic currents (EPSCs) were made from guinea pig hippocampal CA1 pyramidal cells. The sensitivity of paired pulse facilitation (PPF) and EPSC variance to changes in synaptic transmission was investigated and the results were compared with the changes in these parameters evoked by long-term potentiation (LTP). 2. Presynaptic manipulations, such as activation of presynaptic gamma-aminobutyric acid-B receptors by baclofen, blockade of presynaptic adenosine receptors by theophylline, blockade of presynaptic potassium channels by cesium, and increasing the Ca(2+)-Mg2+ ratio in the external recording solution, each reliably changed PPF in a fashion reciprocal to the change in the EPSC amplitude. However, recruitment of additional synaptic release sites by increasing stimulus strength and antagonism of non-N-methyl-D-aspartate (NMDA) glutamate receptors by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) failed to alter PPF. 3. Presynaptic manipulations including increased stimulus strength gave the predicted changes in the value of mean 2/variance (M2/sigma 2). Moreover, postsynaptic manipulations that altered EPSC amplitude, including blockade of non-NMDA receptors by CNQX, or changing the holding potential of the postsynaptic cell, gave little change in M2/sigma 2, as would be predicted for manipulations resulting in a uniform postsynaptic change. 4. LTP caused no change in PPF, whereas the presynaptic manipulations, which caused a similar amount of potentiation to that induced by LTP, significantly decreased PPF. On the other hand, LTP did increase M2/sigma 2, although the increase was less than that predicted for a purely presynaptic mechanism.(ABSTRACT TRUNCATED AT 250 WORDS) Copyright © 1993 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Neurophysiology The American Physiological Society

Modulation of synaptic transmission and long-term potentiation: effects on paired pulse facilitation and EPSC variance in the CA1 region of the hippocampus

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Publisher
The American Physiological Society
Copyright
Copyright © 1993 the American Physiological Society
ISSN
0022-3077
eISSN
1522-1598
Publisher site
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Abstract

Abstract 1. Whole-cell patch-clamp recordings of excitatory postsynaptic currents (EPSCs) were made from guinea pig hippocampal CA1 pyramidal cells. The sensitivity of paired pulse facilitation (PPF) and EPSC variance to changes in synaptic transmission was investigated and the results were compared with the changes in these parameters evoked by long-term potentiation (LTP). 2. Presynaptic manipulations, such as activation of presynaptic gamma-aminobutyric acid-B receptors by baclofen, blockade of presynaptic adenosine receptors by theophylline, blockade of presynaptic potassium channels by cesium, and increasing the Ca(2+)-Mg2+ ratio in the external recording solution, each reliably changed PPF in a fashion reciprocal to the change in the EPSC amplitude. However, recruitment of additional synaptic release sites by increasing stimulus strength and antagonism of non-N-methyl-D-aspartate (NMDA) glutamate receptors by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) failed to alter PPF. 3. Presynaptic manipulations including increased stimulus strength gave the predicted changes in the value of mean 2/variance (M2/sigma 2). Moreover, postsynaptic manipulations that altered EPSC amplitude, including blockade of non-NMDA receptors by CNQX, or changing the holding potential of the postsynaptic cell, gave little change in M2/sigma 2, as would be predicted for manipulations resulting in a uniform postsynaptic change. 4. LTP caused no change in PPF, whereas the presynaptic manipulations, which caused a similar amount of potentiation to that induced by LTP, significantly decreased PPF. On the other hand, LTP did increase M2/sigma 2, although the increase was less than that predicted for a purely presynaptic mechanism.(ABSTRACT TRUNCATED AT 250 WORDS) Copyright © 1993 the American Physiological Society

Journal

Journal of NeurophysiologyThe American Physiological Society

Published: Oct 1, 1993

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