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Lamotrigine inhibits Ca2+ currents in cortical neurons: functional implications
A Stefani1, F Spadoni, A Siniscalchi
1Dipartimento Sanità Pubblica, Università di Tor Vergata, Rome, Italy.
European Journal of Pharmacology
|June 20, 1996
Summary
The antiepileptic drug lamotrigine inhibits high-voltage-activated calcium currents in rat cortical neurons. This action, particularly on N-type and P-type channels, may explain its effectiveness in treating epilepsy and neurotoxicity.
Area of Science:
- Neuroscience
- Pharmacology
- Epilepsy Research
Background:
- High-voltage-activated calcium currents in pyramidal cortical cells influence seizure propagation.
- These currents also regulate excitatory amino acid release at corticostriatal terminals.
Purpose of the Study:
- To investigate the effect of the antiepileptic drug lamotrigine on high-voltage-activated calcium currents in rat cortical neurons.
- To determine the specific calcium channel subtypes modulated by lamotrigine.
Main Methods:
- Electrophysiological recordings in rat cortical neurons.
- Dose-response analysis of lamotrigine's effect on calcium currents.
- Pharmacological blockade experiments using nifedipine, omega-conotoxin GVIA, and omega-agatoxin-IVA.
Main Results:
- Lamotrigine produced a dose-dependent inhibition of high-voltage-activated calcium currents (IC50 = 12.3 microM).
- This inhibition was not affected by nifedipine but was blocked by omega-conotoxin GVIA (N-type) and omega-agatoxin-IVA (P-type) channel blockers.
- Lamotrigine modulates calcium conductances involved in excitatory amino acid release.
Conclusions:
- Lamotrigine, at therapeutic concentrations, modulates calcium channels in the corticostriatal pathway.
- These actions contribute to lamotrigine's efficacy in epilepsy therapy.
- The drug's effect on calcium currents may also be relevant for treating excitatory amino acid-induced neurotoxicity.