Nonlinearities between inhibition and T-type calcium channel activity bidirectionally regulate thalamic oscillations

  1. Adam C Lu  Is a corresponding author
  2. Christine Kyuyoung Lee
  3. Max Kleiman-Weiner
  4. Brian Truong
  5. Megan Wang
  6. John Huguenard  Is a corresponding author
  7. Mark P Beenhakker  Is a corresponding author
  1. University of Virginia, United States
  2. Massachusetts General Hospital, United States
  3. Harvard University, United States
  4. Princeton University, United States
  5. Stanford University School of Medicine, United States

Abstract

Absence seizures result from 3-5 Hz generalized thalamocortical oscillations that depend on highly regulated inhibitory neurotransmission in the thalamus. Efficient reuptake of the inhibitory neurotransmitter GABA is essential, and reuptake failure worsens human seizures. Here, we show that blocking GABA transporters (GATs) in acute rat brain slices containing key parts of the thalamocortical seizure network modulates epileptiform activity. As expected, we found that blocking either GAT1 or GAT3 prolonged oscillations. However, blocking both GATs unexpectedly suppressed oscillations. Integrating experimental observations into single-neuron and network-level computational models shows how a non-linear dependence of T-type calcium channel gating on GABAB receptor activity regulates network oscillations. Receptor activity that is either too brief or too protracted fails to sufficiently open T-type channels necessary for sustaining oscillations. Only within a narrow range does prolonging GABAB receptor activity promote channel opening and intensify oscillations. These results have implications for therapeutics that modulate inhibition kinetics.

Data availability

Source data files have been provided for Figures 1-5, 8-9. Oscillations data, dynamic clamp data are available via Dryad (https://doi.org/10.5061/dryad.4xgxd256f). All code for reproducing results are available online at https://github.com/luadam4c/m3ha_published/.

The following data sets were generated

Article and author information

Author details

  1. Adam C Lu

    Department of Pharmacology, University of Virginia, Charlottesville, United States
    For correspondence
    al4ng@virginia.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1008-1057
  2. Christine Kyuyoung Lee

    Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1422-4606
  3. Max Kleiman-Weiner

    Department of Psychology, Harvard University, Cambridge, MA, United States
    Competing interests
    No competing interests declared.
  4. Brian Truong

    Department of Pharmacology, University of Virginia, Charlottesville, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-0179-0932
  5. Megan Wang

    Princeton Neuroscience Institute, Princeton University, Princeton, NJ, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8845-4936
  6. John Huguenard

    Neurology and Neurological Sciences, Neurosurgery, Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, United States
    For correspondence
    John.Huguenard@stanford.edu
    Competing interests
    John Huguenard, Senior editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6950-1191
  7. Mark P Beenhakker

    Department of Pharmacology, University of Virginia, Charlottesville, United States
    For correspondence
    mpb5y@virginia.edu
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4541-0201

Funding

National Institute of Neurological Disorders and Stroke (NIH grant R01-NS099586)

  • Adam C Lu
  • Brian Truong
  • Mark P Beenhakker

National Institute of Neurological Disorders and Stroke (NIH grant R01-NS034774)

  • Christine Kyuyoung Lee
  • Max Kleiman-Weiner
  • Megan Wang
  • John Huguenard

University of Virginia (Whitfield-Randolph Scholarship)

  • Adam C Lu

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Frances K Skinner, Krembil Research Institute, University Health Network, Canada

Ethics

Animal experimentation: Oscillation experiments were performed in accordance with Protocol #3892 approved by the Institutional Animal Care and Use Committee at the University of Virginia. Dynamic clamp experiments were performed in accordance with protocols approved by the Administrative Panel on Laboratory Animal Care at Stanford University. Rats were deeply anesthetized with pentobarbital before transcardial perfusion, and every effort was made to minimize suffering.

Version history

  1. Received: June 1, 2020
  2. Accepted: September 8, 2020
  3. Accepted Manuscript published: September 9, 2020 (version 1)
  4. Version of Record published: October 1, 2020 (version 2)

Copyright

© 2020, Lu et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 1,515
    views
  • 183
    downloads
  • 6
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Adam C Lu
  2. Christine Kyuyoung Lee
  3. Max Kleiman-Weiner
  4. Brian Truong
  5. Megan Wang
  6. John Huguenard
  7. Mark P Beenhakker
(2020)
Nonlinearities between inhibition and T-type calcium channel activity bidirectionally regulate thalamic oscillations
eLife 9:e59548.
https://doi.org/10.7554/eLife.59548

Share this article

https://doi.org/10.7554/eLife.59548

Further reading

    1. Computational and Systems Biology
    Hedi Chen, Xiaoyu Fan ... Boxue Tian
    Research Article

    Accurate prediction of the structurally diverse complementarity determining region heavy chain 3 (CDR-H3) loop structure remains a primary and long-standing challenge for antibody modeling. Here, we present the H3-OPT toolkit for predicting the 3D structures of monoclonal antibodies and nanobodies. H3-OPT combines the strengths of AlphaFold2 with a pre-trained protein language model and provides a 2.24 Å average RMSD between predicted and experimentally determined CDR-H3 loops, thus outperforming other current computational methods in our non-redundant high-quality dataset. The model was validated by experimentally solving three structures of anti-VEGF nanobodies predicted by H3-OPT. We examined the potential applications of H3-OPT through analyzing antibody surface properties and antibody–antigen interactions. This structural prediction tool can be used to optimize antibody–antigen binding and engineer therapeutic antibodies with biophysical properties for specialized drug administration route.

    1. Computational and Systems Biology
    2. Medicine
    Zachary Shaffer, Roberto Romero ... Nardhy Gomez-Lopez
    Research Article

    Background:

    Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Most cases of preterm birth occur spontaneously and result from preterm labor with intact (spontaneous preterm labor [sPTL]) or ruptured (preterm prelabor rupture of membranes [PPROM]) membranes. The prediction of spontaneous preterm birth (sPTB) remains underpowered due to its syndromic nature and the dearth of independent analyses of the vaginal host immune response. Thus, we conducted the largest longitudinal investigation targeting vaginal immune mediators, referred to herein as the immunoproteome, in a population at high risk for sPTB.

    Methods:

    Vaginal swabs were collected across gestation from pregnant women who ultimately underwent term birth, sPTL, or PPROM. Cytokines, chemokines, growth factors, and antimicrobial peptides in the samples were quantified via specific and sensitive immunoassays. Predictive models were constructed from immune mediator concentrations.

    Results:

    Throughout uncomplicated gestation, the vaginal immunoproteome harbors a cytokine network with a homeostatic profile. Yet, the vaginal immunoproteome is skewed toward a pro-inflammatory state in pregnant women who ultimately experience sPTL and PPROM. Such an inflammatory profile includes increased monocyte chemoattractants, cytokines indicative of macrophage and T-cell activation, and reduced antimicrobial proteins/peptides. The vaginal immunoproteome has improved predictive value over maternal characteristics alone for identifying women at risk for early (<34 weeks) sPTB.

    Conclusions:

    The vaginal immunoproteome undergoes homeostatic changes throughout gestation and deviations from this shift are associated with sPTB. Furthermore, the vaginal immunoproteome can be leveraged as a potential biomarker for early sPTB, a subset of sPTB associated with extremely adverse neonatal outcomes.

    Funding:

    This research was conducted by the Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services (NICHD/NIH/DHHS) under contract HHSN275201300006C. ALT, KRT, and NGL were supported by the Wayne State University Perinatal Initiative in Maternal, Perinatal and Child Health.