Abstracts

Rationale: The period of epileptogenesis after an initiating seizure is critical for therapeutic intervention to prevent the chronic seizure onset that defines epilepsy. Recent studies highlight the role of abnormal glucose metabolism in the epilepsy etiologies. Starvation was used in the time of Hippocrates to treat epilepsy. The ketogenic diet (KD) is effective for certain intractable epilepsies. The basis of KD is a metabolic switch to from glucose to ketone body usage. Lactate dehydrogenase (LDH) was reported as a potential therapeutic target, generating renewed interest in metabolic regulation during epileptogenesis. Additionally, treatment with 2-deoxy glucose, a glycolytic inhibitor, has some pre-clinical efficacy for seizure attenuation. These observations suggest that excessive glucose usage by neuronal and/or glial cells may contribute to epileptogenic progression. Some have suggested that epilepsy is a metabolic disease, yet this area remains largely unexplored. An improved molecular elaboration may advance mechanism-based applications of KD or other metabolism-based therapeutic interventions. Methods: 7 week-old mice were treated with either pilocarpine or kainate and underwent status epileticus with at least two Racine-scale 5 seizures. Mice were sacrificed in a time-course over two weeks and hippocampi dissected from-flash cooled brains for metabolite and molecular analysis, or whole brains were removed from 2% paraformaldehyde-perfused mice for immunohistochemistry. Results: We investigate a Wnt signaling-induced, Warburg-like metabolic reprogramming during early epileptogenesis. Our ongoing work in a general pre-clinical model of epileptogenesis (pilocarpine) has shown that aberrant activation of multiple pathways (Wnt and mTOR) contributes to chronic seizure onset. Both pathways are associated with a Warburg effect, a metabolic reprogramming largely associated with cancer and which sustains the increased biosynthetic needs of rapidly proliferating cells. But, a Warburg-like metabolism is unknown in brain. In our work, we demonstrate that elevated Wnt signaling and a Warburg effect unexpectedly occurs in the hippocampus during early epileptogenesis, including the induction of classic Warburg enzymes such as hexokinase II, PKM2, and LDHA. These isoforms are associated with Warburg-like metabolic rearrangement in numerous cancers. Steady state and kinetic flux analyses using NMR metabolomics identified an unusually high level of glucose metabolism with features of a Warburg metabolic reprogramming (e.g. elevation of lactate and glutamine). Consistent with an epileptogenic hippocampus, GABA levels were decreased. Conclusions: Our observation of elevated glucose use, specific glycolytic enzyme isoform induction, and lactate production are consistent with a Warburg metabolic rearrangement and are quite unexpected for an epileptogenic hippocampus. We are investigating possible roles for a Warburg like re-arrangement in early epileptogenesis. We postulate that our results may predict a unique time window for metabolic intervention to treat epilepsies. Funding: Supported by a grant from the Dept. of Defense