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Opposite effects of T- and L-type Ca(2+) channels blockers in generalized absence epilepsy

G van Luijtelaar1, D Wiaderna, C Elants

  • 1NICI, Department of Comparative and Physiological Psychology, Psychology Laboratory, Nijmegen University, PO Box 9104, 6500 HE, Nijmegen, Netherlands. luitelaar@nici.kun.nl

European Journal of Pharmacology
|October 21, 2000
PubMed

Insights

Ethosuximide (T-type calcium channel blocker) and BAY K8644 (L-type calcium channel opener) reduced absence epilepsy seizures in rats. Nimodipine (L-type blocker) increased seizures, suggesting complex roles for calcium channels in epilepsy.

Area of Science:

  • Neuroscience
  • Pharmacology

Background:

  • Absence epilepsy is a neurological disorder characterized by spike-wave discharges.
  • WAG/Rij rats are a genetic model for studying generalized absence epilepsy.
  • Calcium channels play a critical role in neuronal excitability and epilepsy.

Purpose of the Study:

  • To investigate the effects of T-type and L-type calcium channel modulators on spike-wave discharges in WAG/Rij rats.
  • To explore the potential of targeting specific calcium channel subtypes for absence epilepsy treatment.

Main Methods:

  • Administration of ethosuximide (T-type blocker), nimodipine (L-type blocker), and BAY K8644 (L-type opener) to WAG/Rij rats.
  • Intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administration routes were used.
  • Monitoring and quantification of spike-wave discharges.
  • Preliminary investigation with P/Q-type (MVIIC) and N-type (GVIA) conotoxins.

Main Results:

  • Ethosuximide and BAY K8644 dose-dependently decreased spike-wave discharges.
  • Nimodipine increased spike-wave discharges.
  • BAY K8644 antagonized the effects of nimodipine.
  • Omega-conotoxin GVIA reduced spike-wave discharges but caused adverse behavioral effects, confounding results.

Conclusions:

  • T-type calcium channel blockers and L-type calcium channel openers have opposing effects on absence epilepsy seizures.
  • L-type calcium channel blockers appear to exacerbate seizures.
  • The role of N-type calcium channels requires further investigation due to confounding factors.

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