Age dependence of NMDA receptor involvement in epileptiform activity in rat hippocampal slices

✍ Scribed by Carl Wang; Frances E. Jensen

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 622 KB
• Volume: 23
• Category: Article
• ISSN: 0920-1211
• DOI: 10.1016/0920-1211(95)00086-0

✦ Synopsis

The pattern of epileptiform activity recorded from a number of in vitro seizure models is age dependent: ictal discharges are observed in immature brain slices while interictal bursts are seen in adult brain slices. This study evaluated the involvement of the N-methyl-D-aspartate (NMDA) receptor in the age-dependency of epileptiform activity recorded in area CA1 of hippocampal slices in Mg2+-free medium. Incubation in Mg2+-free medium induced ictal activity in 84% of hippocampal slices from immature rats (postnatal 10-15 days). In contrast, adult slices responded with interictal bursting, while ictal activity was rare (9%). Bath application of the NMDA receptor antagonist D,L-2-amino-5-phosphonovaleric acid (DL-APV, 20 ~M) converted ictal activity to interictal activity in the hippocampal slices from immature rats. In adult slices, bath application of NMDA (10-20 /zM) in Mg2+-free medium induced ictal-like discharges. Perfusion with NMDA (20 /xM) in a medium containing 1.5 mM Mg 2÷ induced ictal activity in immature slices while it evoked only interictal bursts in adult slices. These results suggest that differences in NMDA receptor function may be involved in the age-dependency of epileptiform activity induced by Mg2+-free medium. Enhanced NMDA receptor-mediated activity may partially underlie increased seizure susceptibility in the immature brain.