Anticonvulsant and antiepileptogenic effects of system x c - inactivation in chronic epilepsy models

Epilepsia. 2019 Jul;60(7):1412-1423. doi: 10.1111/epi.16055. Epub 2019 Jun 9.

Abstract

Objective: The cystine/glutamate antiporter system x c - could represent a new target for antiepileptogenic treatments due to its crucial roles in glutamate homeostasis and neuroinflammation. To demonstrate this, we compared epilepsy development and seizure susceptibility in xCT knockout mice (xCT-/- ) and in littermate controls (xCT+/+ ) in different chronic models of epilepsy.

Methods: Mice were surgically implanted with electrodes in the basolateral amygdala and chronically stimulated to develop self-sustained status epilepticus (SSSE); continuous video-electroencephalography monitoring was performed for 28 days after SE and hippocampal histopathology was assessed. Corneal kindling was induced by twice daily electrical stimulation at 6 Hz and maintenance of the fully kindled state was evaluated. Next, messenger RNA (mRNA) and protein levels of xCT and of the proteins involved in the phosphoinositide 3-kinase (PI3K)/Akt/glycogen synthase kinase 3β (GSK-3β)/eukaryotic initiation factor 2α (eIF2α)/activating transcription factor 4 (ATF4) signaling pathway were measured at different time points during epileptogenesis in NMRI mice treated with pilocarpine. Finally, the anticonvulsant effect of sulfasalazine (SAS), a nonselective system x c - inhibitor, was assessed against 6 Hz-evoked seizures in pilocarpine-treated mice.

Results: In the SSSE model, xCT-/- mice displayed a significant delayed epileptogenesis, a reduced number of spontaneous recurrent seizures, and less pronounced astrocytic and microglial activation. Moreover, xCT-/- mice showed reduced seizure severity during 6 Hz kindling development and a lower incidence of generalized seizures during the maintenance of the fully kindled state. In pilocarpine-treated mice, protein levels of the PI3K/Akt/GSK-3β/eIF2α/ATF4 pathway were increased during the chronic phase of the model, consistent with previous findings in the hippocampus of patients with epilepsy. Finally, repeated administration of SAS protected pilocarpine-treated mice against acute 6 Hz seizure induction, in contrast to sham controls, in which system x c - is not activated.

Significance: Inhibition of system x c - could be an attractive target for the development of new therapies with a potential for disease modification in epilepsy.

Keywords: xCT; cystine/glutamate antiporter; disease modification; epilepsy; kindling; status epilepticus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport System y+ / drug effects*
  • Amino Acid Transport System y+ / metabolism
  • Animals
  • Anticonvulsants / pharmacology*
  • Anticonvulsants / therapeutic use
  • Disease Models, Animal
  • Electroencephalography
  • Epilepsy / drug therapy*
  • Epilepsy / etiology
  • Epilepsy / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pilocarpine / pharmacology
  • Status Epilepticus / drug therapy
  • Status Epilepticus / etiology
  • Status Epilepticus / metabolism

Substances

  • Amino Acid Transport System y+
  • Anticonvulsants
  • Slc7a11 protein, mouse
  • Pilocarpine