Abstracts

Rationale: The Kcna1 gene encodes the delayed-rectifier voltage-gated potassium channel alpha subunit, Kv1.1. Kcna1-null mice exhibit frequent recurrent spontaneous seizures by the third post-natal week. Earlier, we observed that the ketogenic diet (KD) reduces seizure frequency and increases the longevity of Kcna1-null mice. Moreover, unprovoked epileptiform activity was observed in acute hippocampal slices from Kcna1-null mice using multi-electrode recording techniques. We asked whether ketone bodies (substrates produced during KD treatment) can reduce this in vitro epileptiform activity. Methods: Using a novel planar multi-electrode array acquisition system (Panasonic MED64), we recorded simultaneous network activity from CA3 & CA1 subfields, and from dentate gyrus. Once baseline activity was established, the ketone bodies β-hydroxybutyrate (BHB) and acetoacetate (ACA) were perfused over the slice for 90 minutes as a cocktail (either 1 mM each, or 5 mM each). Ketone effects on spontaneous interictal-like epileptiform (inter-ILE) activity were assessed during 5 or 10 minute epochs after a 60 minute exposure to ketones. Ketone effects on spontaneous ictal-like epileptiform (ILE) activity were assessed at multiple 5 or 10 minute epochs between the 30 and 90 minute time-points during ketone exposure. Results: Inter-ILEs and ILEs occurred at a frequency of 1.73 ± 0.25 and 0.009 ± 0.002 Hz, respectively. Co-application of BHB and ACA reduced both the inter-ILE and ILE frequencies in a concentration-dependent manner (p<0.05). Conversely, ketones had no effect on input-output curves or paired-pulse facilitation. Application of CNQX (10 μM) eliminated all epileptiform activity. Conclusions: Using a unique microelectrode array, we demonstrate that ketone bodies inhibit spontaneous epileptiform activity in hippocampal slices from epileptic Kcna1-null mice. Our results support the hypothesis that ketone bodies may be responsible, in part, for the anticonvulsant efficacy of the KD.