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TitleEnhancing neuronal chloride extrusion rescues α2/α3 GABA-mediated analgesia in neuropathic pain.
Publication TypeJournal Article
Year of Publication2020
AuthorsLorenzo, Louis-Etienne, Antoine G. Godin, Francesco Ferrini, Karine Bachand, Isabel Plasencia-Fernández, Simon Labrecque, Alexandre A. Girard, Dominic Boudreau, Irenej Kianicka, Martin Gagnon, Nicolas Doyon, Alfredo Ribeiro-da-Silva, and Yves De Koninck
JournalNat Commun
Date Published2020 02 13
KeywordsAnalgesia, Analgesics, Animals, Brain-Derived Neurotrophic Factor, Chlorides, Disease Models, Animal, Fluorobenzenes, GABA-A Receptor Agonists, Ion Transport, Ligands, Male, Neuralgia, Neurons, Peripheral Nerve Injuries, Rats, Rats, Sprague-Dawley, Receptor, trkB, Receptors, GABA-A, Symporters, Synapses, Triazoles

Spinal disinhibition has been hypothesized to underlie pain hypersensitivity in neuropathic pain. Apparently contradictory mechanisms have been reported, raising questions on the best target to produce analgesia. Here, we show that nerve injury is associated with a reduction in the number of inhibitory synapses in the spinal dorsal horn. Paradoxically, this is accompanied by a BDNF-TrkB-mediated upregulation of synaptic GABARs and by an α1-to-α2GABAR subunit switch, providing a mechanistic rationale for the analgesic action of the α2,3GABAR benzodiazepine-site ligand L838,417 after nerve injury. Yet, we demonstrate that impaired Cl extrusion underlies the failure of L838,417 to induce analgesia at high doses due to a resulting collapse in Cl gradient, dramatically limiting the benzodiazepine therapeutic window. In turn, enhancing KCC2 activity not only potentiated L838,417-induced analgesia, it rescued its analgesic potential at high doses, revealing a novel strategy for analgesia in pathological pain, by combined targeting of the appropriate GABAR-subtypes and restoring Cl homeostasis.

Alternate JournalNat Commun
PubMed ID32054836
PubMed Central IDPMC7018745