Abstracts

Rationale: New approaches are needed to mitigate pharmacoresistant seizures. The ketogenic diet is successful in treating pharmacoresistant patients, but adherence can be difficult. Triheptanoin, a medium chain triglyceride containing anaplerotic 7-carbon fatty acids, can be used in a carbohydrate-containing diet and may promote beneficial oxidative metabolism in brain. We previously showed that a triheptanoin (C7) diet was anticonvulsant in two mouse chronic seizure models. In particular, triheptanoin feeding increased the seizure threshold of mice made epileptic with pilocarpine. A limitation of that study was that evoked, not spontaneous seizures were measured. Thus, we tested if the C7 diet reduced spontaneous seizures in the pilocarpine model using video-EEG. A pilot study suggested efficacy of triheptanoin. In this abstract, additional experiments are reported to confirm the preliminary results. Methods: Status epilepticus (SE) was induced in CF-1 mice with pilocarpine. Immediately following SE, mice were fed with the C7 diet (35% by calories) or a standard control diet. To quantify spontaneous seizures, video-EEG was performed using a Pinnacle system. Six screw electrodes were placed bilaterally in the skull and spaced rostral to caudal. Following recovery, freely-moving mice were placed individually in cages and monitored for 12 hour periods, at least once a week. Video-EEG activity was acquired and quantified using Sirenia software. Video analysis confirmed that all electrographic seizures showed a behavioral correlate. Control mice (no SE) never showed seizure activity. Hippocampal sections from diet and control mice were subsequently processed and examined for neuropathological changes. Results: Control mice showed a range of 0 to 17 seizures per 12 hr period. C7 mice showed 0 to 16 seizures per 12 hr period. Seizures were not homogeneously distributed in the recording period. Seizures often clustered, with a period of numerous seizures flanked by periods of no or few seizures. Clustering complicated statistical analysis. Thus, three separate experiments were performed and the results pooled. C7 mice showed 36% reduction in spontaneous seizures compared to control mice, which was statistically significant (p=0.0407). C7 mice had more seizure-free recording periods (72%) compared to mice on the control diet (58%, p < 0.0001). Also. the percentage of severe, stage 5 seizures was lower in C7 mice. However, seizure duration remained unaffected by the diet. The degree of neuropathology correlated with seizure frequency, but not dietary treatment. When examining the experiments separately, C7 mice had a 50% lower seizure frequency in the first and third experiments, but no reduction in seizure frequency in the second experiment. This illustrates the difficulty presented by clustering. In one experiment, mice switched diets after 12 weeks and recording continued. Mice switched to the C7 diet showed reduced seizure frequency after the switch, while mice switched from C7 to control diet maintained the same reduced frequency, suggesting the effect of triheptanoin is persistent and effective months after epilepsy begins. Conclusions: The reduction in seizure frequency and increased number of seizure free recording periods support the hypothesis that triheptanoin is effective in epileptic mice. Also, since the diet was given during the latent period, triheptanoin may also be anti-epileptogenic. Future studies will be directed to identifying the mechanism(s) by which triheptanoin reduces seizures in epileptic mice. Funding: Funding provided by NIH grant R15NS060105 and a grant from the Laura W Bush Institute for Women's Health