Calorie restriction and ketogenic diet diminish neuronal excitability in rat dentate gyrus in vivo

Purpose: The ketogenic diet (KD) is an effective treatment for intractable epilepsy. However, little is known about its underlying mechanisms. Methods: In this study, in vivo extracellular field responses to angular bundle stimulation were recorded in the dentate gyrus of Sprague-Dawley rats fed one of three diets: ketogenic calorie-restricted (KCR), normal calorie-restricted (NCR), or normal ad libitum (NAL). Input/output curves and paired-pulse relations were used to assess network excitability. A maximal dentate activation (MDA) protocol was used to measure electrographic seizure threshold and duration. Results: Animals fed calorie-restricted (CR) diets exhibited greater paired-pulse inhibition, an elevated MDA threshold, and an absence of spreading depression-like events compared with ad libitum-fed controls, In the MDA model of epileptogenesis, the rate of increase in electrographic seizure duration after repeated stimuli was markedly reduced in KCR-fed animals compared with NCR- and NAL-fed controls. Conclusions: These data suggest that CR, by itself, can be anticonvulsant, and treatment with a KCR diet may be both anticonvulsant and antiepileptogenic.