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Shunting of excitatory input to dentate gyrus granule cells by a depolarizing GABAA receptor-mediated postsynaptic conductance.
J Neurophysiol. 1992 Jul; 68(1):197-212.JN

Abstract

1. Stimulation of the perforant path in the outer molecular layer of the adult rat dentate gyrus produced a depolarizing post-synaptic potential (DPSP) in granule cells when recorded using whole-cell techniques in the standard hippocampal slice preparation at 34 degrees C. The postsynaptic currents (PSCs) contributing to the DPSP were analyzed using specific receptor antagonists in current- and voltage-clamp recordings. 2. The DPSP reversal potential was dependent on the intracellular chloride concentration, and the amplitude of the DPSP was increased 55% after perfusion of the gamma-aminobutyric acid-A (GABAA) receptor antagonist bicuculline methiodide (BMI). The GABAA receptor-mediated PSC reversed at -66 mV, which was 19 mV positive to the resting membrane potential (-85 mV) but hyperpolarized relative to action potential threshold. At -35 mV, the GABAA PSC had a latency to peak of 12.9 ms after the stimulus and decayed monoexponentially with an average time constant of 23.4 ms. 3. The component of the PSC blocked by the Quis/AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) had a latency to peak of 7.1 ms and decayed monoexponentially with a time constant of 9.9 ms at -35 mV. The N-methyl-D-aspartate (NMDA) receptor-mediated PSC, which was blocked by D-amino-5-phosphonovaleric acid (D-AP5), had a waveform that was similar to the GABAA PSC: the latency to peak was 16 ms and the decay was monoexponential with a time constant of 24.5 ms at -35 mV. 4. The ratio of the peak PSCs mediated by GABAA, Quis/AMPA, and NMDA receptors measured at -35 mV with cesium gluconate electrode solutions was 1:0.2:0.1. This ratio was essentially constant over the range of stimulus intensities that produced compound PSC amplitudes of 80-400 pA. 5. Measured at its reversal potential, the GABAA receptor-mediated postsynaptic conductance (GGABA-A) decreased the peak DPSP amplitude by 35%, shunted 50% of the charge transferred to the soma by the excitatory PSC, and completely inhibited the NMDA receptor-mediated component of the DPSP. 6. Simultaneous stimulation of presynaptic fibers from both the perforant path and interneurons results in a large depolarizing GGABA-A that inhibits the granule cell by shunting the excitatory PSCs. As predicted by models of shunting, the similar kinetics of the GABAA and NMDA PSCs leads to particularly effective inhibition of the NMDA PSC. The more rapid Quis/AMPA PSC is less affected by the GGABA-A, so that granule cell excitation under these conditions is primarily due to Quis/AMPA receptor activation.

Authors+Show Affiliations

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, California 94305.No affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

1381418

Citation

Staley, K J., and I Mody. "Shunting of Excitatory Input to Dentate Gyrus Granule Cells By a Depolarizing GABAA Receptor-mediated Postsynaptic Conductance." Journal of Neurophysiology, vol. 68, no. 1, 1992, pp. 197-212.
Staley KJ, Mody I. Shunting of excitatory input to dentate gyrus granule cells by a depolarizing GABAA receptor-mediated postsynaptic conductance. J Neurophysiol. 1992;68(1):197-212.
Staley, K. J., & Mody, I. (1992). Shunting of excitatory input to dentate gyrus granule cells by a depolarizing GABAA receptor-mediated postsynaptic conductance. Journal of Neurophysiology, 68(1), 197-212.
Staley KJ, Mody I. Shunting of Excitatory Input to Dentate Gyrus Granule Cells By a Depolarizing GABAA Receptor-mediated Postsynaptic Conductance. J Neurophysiol. 1992;68(1):197-212. PubMed PMID: 1381418.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Shunting of excitatory input to dentate gyrus granule cells by a depolarizing GABAA receptor-mediated postsynaptic conductance. AU - Staley,K J, AU - Mody,I, PY - 1992/7/1/pubmed PY - 1992/7/1/medline PY - 1992/7/1/entrez SP - 197 EP - 212 JF - Journal of neurophysiology JO - J Neurophysiol VL - 68 IS - 1 N2 - 1. Stimulation of the perforant path in the outer molecular layer of the adult rat dentate gyrus produced a depolarizing post-synaptic potential (DPSP) in granule cells when recorded using whole-cell techniques in the standard hippocampal slice preparation at 34 degrees C. The postsynaptic currents (PSCs) contributing to the DPSP were analyzed using specific receptor antagonists in current- and voltage-clamp recordings. 2. The DPSP reversal potential was dependent on the intracellular chloride concentration, and the amplitude of the DPSP was increased 55% after perfusion of the gamma-aminobutyric acid-A (GABAA) receptor antagonist bicuculline methiodide (BMI). The GABAA receptor-mediated PSC reversed at -66 mV, which was 19 mV positive to the resting membrane potential (-85 mV) but hyperpolarized relative to action potential threshold. At -35 mV, the GABAA PSC had a latency to peak of 12.9 ms after the stimulus and decayed monoexponentially with an average time constant of 23.4 ms. 3. The component of the PSC blocked by the Quis/AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) had a latency to peak of 7.1 ms and decayed monoexponentially with a time constant of 9.9 ms at -35 mV. The N-methyl-D-aspartate (NMDA) receptor-mediated PSC, which was blocked by D-amino-5-phosphonovaleric acid (D-AP5), had a waveform that was similar to the GABAA PSC: the latency to peak was 16 ms and the decay was monoexponential with a time constant of 24.5 ms at -35 mV. 4. The ratio of the peak PSCs mediated by GABAA, Quis/AMPA, and NMDA receptors measured at -35 mV with cesium gluconate electrode solutions was 1:0.2:0.1. This ratio was essentially constant over the range of stimulus intensities that produced compound PSC amplitudes of 80-400 pA. 5. Measured at its reversal potential, the GABAA receptor-mediated postsynaptic conductance (GGABA-A) decreased the peak DPSP amplitude by 35%, shunted 50% of the charge transferred to the soma by the excitatory PSC, and completely inhibited the NMDA receptor-mediated component of the DPSP. 6. Simultaneous stimulation of presynaptic fibers from both the perforant path and interneurons results in a large depolarizing GGABA-A that inhibits the granule cell by shunting the excitatory PSCs. As predicted by models of shunting, the similar kinetics of the GABAA and NMDA PSCs leads to particularly effective inhibition of the NMDA PSC. The more rapid Quis/AMPA PSC is less affected by the GGABA-A, so that granule cell excitation under these conditions is primarily due to Quis/AMPA receptor activation. SN - 0022-3077 UR - https://www.unboundmedicine.com/medline/citation/1381418/Shunting_of_excitatory_input_to_dentate_gyrus_granule_cells_by_a_depolarizing_GABAA_receptor_mediated_postsynaptic_conductance_ L2 - https://journals.physiology.org/doi/10.1152/jn.1992.68.1.197?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -