Abstracts

Rationale: Previous studies have suggested that the ketogenic diet (KD) and its metabolites possess neuroprotective properties. However, neuroprotection afforded by the KD has yet to be demonstrated in a spontaneous developmental epilepsy model. Accordingly, we asked whether the KD and/or phenobarbital (both commonly used to treat pediatric patients with epilepsy) exert morphological neuroprotective effects in the hippocampus of intrinsically epileptic Kcna1-null mice (lacking the voltage-gated Shaker-like potassium channel Kv1.1 alpha-subunit). Methods: Kcna1-null (KO) mice generated on a C3H background were treated for 2 weeks with either the KD (BioServ F3666) or phenobarbital (PB) (30 mg/kg daily, diluted in saline via IP injection) immediately upon weaning at P20. Animals were sacrificed at P35. Brain tissue was harvested and flash frozen in 2-methylbutane. Coronal sections were cut at 50μm, and stained with hematoxylin/eosin. Stereological analysis was performed using Bioquant Life Sciences software (Nashville, TN) and a Zeiss Axioskop microscope outfitted with a motorized stage (Applied Scientific Instrumentation, Eugene, OR). Quantification was done using the optical fractionator method. Cell reference volume and cell counting were outlined and implemented at 4X and 63X, respectively. Pyramidal cells from every other section (with a random starting section) were counted in the CA1 hippocampal region using the dissector probe. The average number of actual cells counted, ΣQ-, ranged from 200 to 350 cells per section (~100 probes), to achieve a mean coefficient of error (CE) of 5-10%. Data were analyzed with one-way ANOVA. Results: The estimated cell counts in the pyramidal layer of CA1 hippocampus in wild-type mice averaged 22,517 (n=5; CE=0.061). In contrast, CA1 pyramidal cell counts were significantly (p=0.002) reduced in KO mice (16,921; n=4; CE=0.071). The estimated cell count for KD-treated KO animals was similar to that of WT animals (19,939; n=4; CE=0.065; p=0.094). Phenobarbital treatment did not restore CA1 cell counts in KO animals (17,350; n=3; CE= 0.062), and was statistically different from the WT animals fed a standard diet (p=0.002). Conclusions: In chronically epileptic Kcna1-null mice, there is a significant reduction in the number of CA1 pyramidal cells compared to wild-type control mice, and the ketogenic diet (but not phenobarbital) appears to exert a morphological neuroprotective effect. Whether this is due to an attenuation of spontaneous recurrent seizures and/or a direct effect of the KD is unknown.