Abstracts

Rationale: The antiepileptic and neuroprotective effects of an array of drugs were studied in a moderate-throughput screen utilizing the accelerated course of epileptogenesis in the in vitro organotypic hippocampal slice culture model of post-traumatic epilepsy. Methods: Organotypic hippocampal slices cultures were prepared from postnatal day 6 or 7 Sprague-Dawley rats and were maintained for 28 days at 37^oC on a rocking platform in a culture medium consisting of Neurobasal-A, B27, 0.5 mM GlutaMAX, and 30 µg/ml Gentamicin. Spent culture media was collected at media changes every 3-4 days and stored at -80^oC until analysis. Drugs, obtained primarily from the NINDS Custom Collection of compounds, were dissolved in DMSO (final concentration 0.1%) and added to the media starting on DIV 3. All experiments included DMSO control slice cultures derived from the same animal. Lactate and lactate dehydrogenase (LDH) concentrations were measured in collected culture media and plotted as cumulative values over 28 days in vitro. Results: Lactate and LDH concentration measurements in the collected culture medium were strongly correlated with electrographic seizure activity and propidium iodide assays for cell death, respectively, and were used in subsequent experiments as assays for seizure activity and neuroprotection. We have screened over 100 drugs, with most drugs screened at multiple concentrations. Several drugs exhibited dose-dependent anticonvulsive or proconvulsive effects, as well as neuroprotective or neurotoxic effects. Conclusions: The correlation between anticonvulsant and neuroprotective effects was likely due to reductions in ictal cell death. Drugs with significant antiepileptic and neuroprotective effects are being retested including 10-day wash-out experiments to differentiate anticonvulsant from antiepileptogenic effects.