KCC2 downregulation after sciatic nerve injury enhances motor function recovery

Autor: Dennis Lawrence Cheung, Takuya Toda, Madoka Narushima, Kei Eto, Chitoshi Takayama, Tatsuko Ooba, Hiroaki Wake, Andrew John Moorhouse, Junichi Nabekura
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Scientific Reports, Vol 13, Iss 1, Pp 1-19 (2023)
Druh dokumentu: article
ISSN: 2045-2322
DOI: 10.1038/s41598-023-34701-y
Popis: Abstract Injury to mature neurons induces downregulated KCC2 expression and activity, resulting in elevated intracellular [Cl−] and depolarized GABAergic signaling. This phenotype mirrors immature neurons wherein GABA-evoked depolarizations facilitate neuronal circuit maturation. Thus, injury-induced KCC2 downregulation is broadly speculated to similarly facilitate neuronal circuit repair. We test this hypothesis in spinal cord motoneurons injured by sciatic nerve crush, using transgenic (CaMKII-KCC2) mice wherein conditional CaMKIIα promoter-KCC2 expression coupling selectively prevents injury-induced KCC2 downregulation. We demonstrate, via an accelerating rotarod assay, impaired motor function recovery in CaMKII-KCC2 mice relative to wild-type mice. Across both cohorts, we observe similar motoneuron survival and re-innervation rates, but differing post-injury reorganization patterns of synaptic input to motoneuron somas—for wild-type, both VGLUT1-positive (excitatory) and GAD67-positive (inhibitory) terminal counts decrease; for CaMKII-KCC2, only VGLUT1-positive terminal counts decrease. Finally, we recapitulate the impaired motor function recovery of CaMKII-KCC2 mice in wild-type mice by administering local spinal cord injections of bicuculline (GABAA receptor blockade) or bumetanide (lowers intracellular [Cl−] by NKCC1 blockade) during the early post-injury period. Thus, our results provide direct evidence that injury-induced KCC2 downregulation enhances motor function recovery and suggest an underlying mechanism of depolarizing GABAergic signaling driving adaptive reconfiguration of presynaptic GABAergic input.
Databáze: Directory of Open Access Journals
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