Hyperexcitable interneurons trigger cortical spreading depression in an Scn1a migraine model
Eva Auffenberg, … , Nikolaus Plesnila, Tobias Freilinger
Eva Auffenberg, … , Nikolaus Plesnila, Tobias Freilinger
Published September 21, 2021
Citation Information: J Clin Invest. 2021;131(21):e142202. https://doi.org/10.1172/JCI142202.
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Research Article Neuroscience

Hyperexcitable interneurons trigger cortical spreading depression in an Scn1a migraine model

Abstract

Cortical spreading depression (CSD), a wave of depolarization followed by depression of cortical activity, is a pathophysiological process implicated in migraine with aura and various other brain pathologies, such as ischemic stroke and traumatic brain injury. To gain insight into the pathophysiology of CSD, we generated a mouse model for a severe monogenic subtype of migraine with aura, familial hemiplegic migraine type 3 (FHM3). FHM3 is caused by mutations in SCN1A, encoding the voltage-gated Na+ channel NaV1.1 predominantly expressed in inhibitory interneurons. Homozygous Scn1aL1649Q knock-in mice died prematurely, whereas heterozygous mice had a normal lifespan. Heterozygous Scn1aL1649Q knock-in mice compared with WT mice displayed a significantly enhanced susceptibility to CSD. We found L1649Q to cause a gain-of-function effect with an impaired Na+-channel inactivation and increased ramp Na+ currents leading to hyperactivity of fast-spiking inhibitory interneurons. Brain slice recordings using K+-sensitive electrodes revealed an increase in extracellular K+ in the early phase of CSD in heterozygous mice, likely representing the mechanistic link between interneuron hyperactivity and CSD initiation. The neuronal phenotype and premature death of homozygous Scn1aL1649Q knock-in mice was partially rescued by GS967, a blocker of persistent Na+ currents. Collectively, our findings identify interneuron hyperactivity as a mechanism to trigger CSD.

Authors

Eva Auffenberg, Ulrike B.S. Hedrich, Raffaella Barbieri, Daniela Miely, Bernhard Groschup, Thomas V. Wuttke, Niklas Vogel, Philipp Lührs, Ilaria Zanardi, Sara Bertelli, Nadine Spielmann, Valerie Gailus-Durner, Helmut Fuchs, Martin Hrabě de Angelis, Michael Pusch, Martin Dichgans, Holger Lerche, Paola Gavazzo, Nikolaus Plesnila, Tobias Freilinger

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Figure 1

Generation of Scn1aL1649Q knock-in mice.

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Generation of Scn1aL1649Q knock-in mice. (A) The mutation p.Leu1649Gln (...
(A) The mutation p.Leu1649Gln (L1649Q) is located in segment 4 (S4) of domain IV of the voltage gated sodium channel NaV1.1. (B) Scheme of important parts of the Scn1a WT allele, the targeting vector, and the mutated allele after homologous recombination. White boxes indicate exons; triangles indicate F3 sites. Restriction sites of MscI and AvrII are depicted; the probes used for Southern blot and the length of the individual restriction fragments after digestion of genomic DNA are indicated in the scheme. (C) Proof of homologous recombination of 5′-side (upper blot) and 3′-side (lower blot) by Southern blot analysis. For Southern blot analysis, MscI (5′-side) and AvrII (3′-side) digested genomic DNA of mutant and WT mice were used. (D) Sequencing trail showing correct insertion of c.4946T>A (asterisk), predicting L1649Q on the protein level. (E) Genotyping of Scn1aL1649Q offspring by PCR analysis of genomic DNA.