SGK1.1 Activation Induces Neuroprotection Against Kainic Acid-Induced Seizures by Upregulation of the M-Current
Abstract number :
1.174
Submission category :
3. Neurophysiology / 3F. Animal Studies
Year :
2018
Submission ID :
500736
Source :
www.aesnet.org
Presentation date :
12/1/2018 6:00:00 PM
Published date :
Nov 5, 2018, 18:00 PM
Authors :
Elva Martin-Batista, Universidad de la Laguna; Laura E. Maglio, Universidad de la Laguna; Natalia Armas-Capote, Universidad de la Laguna; Guadalberto Hernandez, Universidad de la Laguna; Diego Alvarez de la Rosa, Universidad de la Laguna; and Teresa Giral
Rationale: Activation of SGK1.1, the neuronal isoform of the serum and glucocorticoid regulated kinase 1 (SGK1), leads to up-regulation of the M-current mediated by Kv7 channels with a significant impact on neuronal excitability (Miranda et al, J Neurosci 2013, 33:2684). We have now further studied the mechanisms underlying SGK1.1-mediated protection against seizures and its putative neuroprotective role. Methods: Using a transgenic mouse with a constitutively active form of SGK1 (Tg.sgk1), we evaluated seizure behaviour (Racine) of WT and Tg.sgk1 mice under two epileptic paradigms: kainic acid (KA) and pilocarpine. Neuronal damage was quantified using fluoro-jade C for neuronal death and GFAP and Iba-1 labelling for gliosis. Phosphorylation of SGK-1 target Nedd4-2 in HEK cells and brain tissue was analyzed by western blot with specific anti-P-S448-Nedd4-2. Results: Tg.sgk1 mice were resistant to acute KA-induced seizures and displayed decreased mortality (Multiple t-test, p=0,002. WT n=26, Tg.sgk1 n=24) Pretreatment with the M-current inhibitor XE991 abolished the differences in seizures behaviour between WT and Tg.sgk1. No differences were found when the muscarinic agonist pilocarpine was used to acutely induce the seizures. We observed a reduction in cell death (Mann-Whitney test, p= 0,0079 WT n=5, Tg.sgk1 n=5) in cortex, hippocampus and amygdala of KA-treated Tg.sgk1 mice reaching tonic-clonic seizures (Racine stage 6), when compared to WT. A similar reduction was found in glial activation (astro- and microgliosis), a process that is associated to epileptogenesis. Immunoblotting showed an increase of phosphorylated Nedd4-2 (Unpaired t-test, p=0,0214. WT n=3, Tg.sgk1=3), a known target of SGK1 in the control of Kv7 channels, in brain tissue from transgenic mice expressing a constitutively active form of SGK1.1. Conclusions: Our results demonstrate that up-regulation of Kv7 channels/M-current driven by SGK1.1 activation constitutes the main protection mechanism underlying the significant reduction in neuronal death and gliosis following KA-induced seizures. Funding: This work has been funded by MINECO grant BFU2015-66490-R.