title: Effect of intracranial administration of ethosuximide in rats with spontaneous or pentylenetetrazol-induced spike-wave discharges.
abstract: OBJECTIVE
  Generalized absence seizures are characterized by bilateral spike-wave discharges (SWDs), particularly in the frontoparietal cortical region. In WAG/Rij and GAERS rats with absence epilepsy, recent evidence indicates that SWDs arise first from the lateral somatosensory cortex (LSC), that is, the cortical focus theory. To further understand the cortical role in SWD generation, two epileptic rat models were assessed.
  
  
  METHODS
  Two models, Long-Evans rats with spontaneous SWDs and Wistar rats with low-dose pentylenetetrazol-induced SWDs (20 mg/kg, i.p.), were administered intracortical or intrathalamic ethosuximide (ESM) or saline. Electroencephalographic recordings were analyzed before and after intracranial microinfusion to evaluate onset, frequency, and duration of SWDs.
  
  
  RESULTS
  In both epileptic rat models, ESM in the LSC significantly reduced SWD number, shortened SWD duration, and delayed SWD onset compared to saline. By contrast, ESM in the medial somatosensory cortex had little effect compared to saline. Intrathalamic infusion of ESM only delayed SWD onset.
  
  
  CONCLUSIONS
  These findings suggest that the LSC may be essential for the occurrence of SWDs. Our data support the cortical focus theory for the generation of absence seizures.
authors: Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, College of Medicine, Chang Gung University, 1 University Road, Tainan, Taiwan.
authors: Shang-Der
authors: SD
authors: Chen
authors: Keng-Hung
authors: KH
authors: Yeh
authors: Yu-Hsing
authors: YH
authors: Huang
authors: Fu-Zen
authors: FZ
authors: Shaw
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use*; D001921:Brain / Q000187:drug effects / Q000503:physiopathology; D004195:Disease Models, Animal; D004832:Epilepsy, Absence / Q000139:chemically induced / Q000188:drug therapy*; D005013:Ethosuximide / Q000494:pharmacology / Q000627:therapeutic use*; D057967:Infusions, Intraventricular; D008297:Male; D010433:Pentylenetetrazole / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D017208:Rats, Wistar
chemical_list: D000927:Anticonvulsants; D005013:Ethosuximide; D010433:Pentylenetetrazole