The Journal of Neuroscience, November 1, 1999, 19(21):9412-9425
Unilateral GluR2(B) Hippocampal Knockdown: A Novel Partial
Seizure Model in the Developing Rat
Linda K.
Friedman1, 2 and
Alexei R.
Koudinov3
1 Department of Neuroscience, Seton Hall University,
South Orange, New Jersey 07079, Department of
Neuroscience, New Jersey Neuroscience Institute, Edison, New Jersey,
2 Albert Einstein College of Medicine, Bronx, New York,
and 3 Department of Neurobiology, Weizmann Institute,
Rehovot, Israel
Kainic acid (KA) induces status epilepticus in both adult and young
rats but with different consequences on pathology and gene expression.
In adults, GluR2(B) AMPA subunit expression is markedly reduced in CA3
neurons before neurodegeneration. In pups, the GluR2(B) subunit is
sustained, possibly contributing to neuronal survival. Mechanisms
underlying the reduced vulnerability of developing neurons to seizures
was investigated by examining the effects of unilateral microinfusions
of GluR2(B) antisense oligodeoxynucleotides (AS-ODNs) into the
hippocampus of young rats in the presence or absence of a subconvulsive
dose of KA. GluR2(B) AS-ODN infusions resulted in spontaneous
seizure-like behavior, high stimulus intensity population spikes in the
absence of long-term potentiation, and neurodegeneration of CA3 neurons
lateral to the infusion site. Electroencephalography revealed
paroxysmal activity and high-frequency high-amplitude discharges
associated with vigorous and continuous scratching, wild running, or
bilateral jerking movements. Pups lacking phenotypic behavior exhibited
high-rhythmic oscillations and status epilepticus by the dose of KA
used. Radiolabeled AS-ODNs accumulated throughout the ipsilateral
dorsal hippocampus. GluR2(B) but not GluR1(A) receptor protein was
markedly reduced after GluR2(B) knockdown. In contrast, GluR1(A)
knockdown reduced GluR1(A) but not GluR2(B) protein without change in
behavior or morphology. Therefore, unilateral downregulation of
hippocampal GluR2(B) but not GluR1(A) protein reduces the seizure
threshold and survival of CA3 neurons in the immature hippocampus,
possibly providing a novel partial seizure model in the developing rat.
Key words:
epilepsy; development; GluR2(B); knockdown; hippocampus; neurodegeneration
Copyright © 1999 Society for Neuroscience 0270-6474/99/19219412-14$05.00/0