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Differences between the scaling of miniature IPSCs and EPSCs recorded in the dendrites of CA1 mouse pyramidal neurons.
J Physiol 2006; 576(Pt 1):191-6JP

Abstract

Anatomical studies have described inhibitory synaptic contacts on apical dendrites, and an abundant number of GABAergic synapses on the somata and proximal dendrites of CA1 pyramidal cells of the hippocampus. The number of inhibitory contacts decreases dramatically with distance from the soma, but the local electrophysiological characterization of these synapses at their site of origin in the dendrites is missing. We directly recorded dendritic GABA receptor-mediated inhibitory synaptic events in adult mouse hippocampal CA1 pyramidal neurons and compared them to excitatory synaptic currents recorded at the same sites. Miniature GABAergic events were evoked using localized application of a hyperosmotic solution to the apical dendrites in the vicinity of the dendritic whole-cell recording pipette. Glutamatergic synaptic events were blocked by kynurenic acid, leaving picrotoxin-sensitive IPSCs. We measured the amplitude and kinetic properties of mIPSCs at the soma and at three different dendritic locations. The amplitude of mIPSCs recorded at the various sites was similar along the somato-dendritic axis. The rise- and decay-times of local mIPSCs were also independent of the location of the synapses. The frequency of mIPSCs was 5 Hz at the soma, in contrast to < 0.5 Hz at dendritic sites, which could be increased to 10-20 Hz and 6-10 Hz, respectively, by our hyperosmotic stimulation protocol. Miniature glutamatergic events were evoked with the same protocol after blocking inhibitory synapses by bicucculine. The measured amplitudes increased along the somato-dendritic axis proportionally with their distance from the soma. The measured kinetic properties were independent of location. Consistent with the idea that IPSCs may have a restricted local effect in the dendrites, our data show a lack of distance-dependent scaling of miniature inhibitory synaptic events, in contrast to the scaling of excitatory events recorded at the same sites.

Authors+Show Affiliations

Neuroscience Center, Louisiana State University Health Science Center, 2020 Gravier St, New Orleans, 70112, USA. bandra@lsuhsc.eduNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

16887875

Citation

Andrásfalvy, Bertalan K., and Istvan Mody. "Differences Between the Scaling of Miniature IPSCs and EPSCs Recorded in the Dendrites of CA1 Mouse Pyramidal Neurons." The Journal of Physiology, vol. 576, no. Pt 1, 2006, pp. 191-6.
Andrásfalvy BK, Mody I. Differences between the scaling of miniature IPSCs and EPSCs recorded in the dendrites of CA1 mouse pyramidal neurons. J Physiol (Lond). 2006;576(Pt 1):191-6.
Andrásfalvy, B. K., & Mody, I. (2006). Differences between the scaling of miniature IPSCs and EPSCs recorded in the dendrites of CA1 mouse pyramidal neurons. The Journal of Physiology, 576(Pt 1), pp. 191-6.
Andrásfalvy BK, Mody I. Differences Between the Scaling of Miniature IPSCs and EPSCs Recorded in the Dendrites of CA1 Mouse Pyramidal Neurons. J Physiol (Lond). 2006 Oct 1;576(Pt 1):191-6. PubMed PMID: 16887875.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Differences between the scaling of miniature IPSCs and EPSCs recorded in the dendrites of CA1 mouse pyramidal neurons. AU - Andrásfalvy,Bertalan K, AU - Mody,Istvan, Y1 - 2006/08/03/ PY - 2006/8/5/pubmed PY - 2006/12/9/medline PY - 2006/8/5/entrez SP - 191 EP - 6 JF - The Journal of physiology JO - J. Physiol. (Lond.) VL - 576 IS - Pt 1 N2 - Anatomical studies have described inhibitory synaptic contacts on apical dendrites, and an abundant number of GABAergic synapses on the somata and proximal dendrites of CA1 pyramidal cells of the hippocampus. The number of inhibitory contacts decreases dramatically with distance from the soma, but the local electrophysiological characterization of these synapses at their site of origin in the dendrites is missing. We directly recorded dendritic GABA receptor-mediated inhibitory synaptic events in adult mouse hippocampal CA1 pyramidal neurons and compared them to excitatory synaptic currents recorded at the same sites. Miniature GABAergic events were evoked using localized application of a hyperosmotic solution to the apical dendrites in the vicinity of the dendritic whole-cell recording pipette. Glutamatergic synaptic events were blocked by kynurenic acid, leaving picrotoxin-sensitive IPSCs. We measured the amplitude and kinetic properties of mIPSCs at the soma and at three different dendritic locations. The amplitude of mIPSCs recorded at the various sites was similar along the somato-dendritic axis. The rise- and decay-times of local mIPSCs were also independent of the location of the synapses. The frequency of mIPSCs was 5 Hz at the soma, in contrast to < 0.5 Hz at dendritic sites, which could be increased to 10-20 Hz and 6-10 Hz, respectively, by our hyperosmotic stimulation protocol. Miniature glutamatergic events were evoked with the same protocol after blocking inhibitory synapses by bicucculine. The measured amplitudes increased along the somato-dendritic axis proportionally with their distance from the soma. The measured kinetic properties were independent of location. Consistent with the idea that IPSCs may have a restricted local effect in the dendrites, our data show a lack of distance-dependent scaling of miniature inhibitory synaptic events, in contrast to the scaling of excitatory events recorded at the same sites. SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/16887875/Differences_between_the_scaling_of_miniature_IPSCs_and_EPSCs_recorded_in_the_dendrites_of_CA1_mouse_pyramidal_neurons_ L2 - https://doi.org/10.1113/jphysiol.2006.115428 DB - PRIME DP - Unbound Medicine ER -