J Korean Epilepsy Soc.  2006 Jun;10(1):35-40.

Combined Application of Bicuculline and 4-Aminopyridine-Induced Epileptiform Activity are Resistant to Conventional Anticonvulsants and AMPA in Young Rat Visual Cortex

• Choi BJ

Abstract

PURPOSE: The goal of the present study was to find out whether blockade of GABAergic synaptic transmission by bicuculline (BIC) in the presence of 4-aminopyridine (4-AP) would lead to expression or suppression of epileptiform activity in the immature brain and to observe the effect of commonly used anticonvulsants (valproic acid (VPA), carbamazepine (CBZP)) and 6-cyano-7-nitroquinoxalinedione (CNQX) on that epileptiform activity.
METHODS
The visual cortex slices were obtained from 14-18 day-old Sprague-Dawley rats. Extracellular cellular recording was performed to observe the induction of epileptiform activity perfused by artificial CSF (ACSF) with combined application of BIC and 4-AP and the effect of VPA, CBZP and CNQX on that epileptiform activity for at least 1 hour.
RESULTS
Epileptiform activity perfused by ACSF with combined application of BIC and 4-AP was insensitive to commonly used anticonvulsants (VPA, CBZP) and sensitive to CNQX.
CONCLUSION
This study suggests that the epileptiform activity induced by combined application of BIC and 4-AP is present even in immature visual cortex slices. And, the blockade of GABAergic inhibition by BIC under 4-AP showed the increase of immature brain excitability as mature brain. The attenuation of that epileptiform activity by a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonist (CNQX) showed that AMPA receptor had relevance to the induction of that epileptiform activity.

Keyword

GABA; Seizure; Visual cortex

MeSH Terms

4-Aminopyridine
6-Cyano-7-nitroquinoxaline-2,3-dione
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid*
Animals
Anticonvulsants*
Bicuculline*
Brain
Carbamazepine
gamma-Aminobutyric Acid
Rats*
Rats, Sprague-Dawley
Receptors, AMPA
Seizures
Synaptic Transmission
Visual Cortex*
4-Aminopyridine
6-Cyano-7-nitroquinoxaline-2,3-dione
Anticonvulsants
Bicuculline
Carbamazepine
Receptors, AMPA
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
gamma-Aminobutyric Acid