Abstracts

Rationale: We tested whether β-hydroxybutyrate (BHB) and the specific lactate dehydrogenase (LDH) inhibitor, oxamate, can terminate Status Epilepticus (SE), which is a neurological emergency requiring rapid seizure termination to protect life and neurons. The ketogenic diet (KD) is a promising remedy for patients with refractory SE. However, it takes time to attain ketosis in patients with ongoing SE. Therefore, drugs that could mimic the therapeutic effect of KD action but act much faster are desirable.

Methods: SE was induced by continuous hippocampal stimulation as previously described (Lewczuk et. al. 2018). Briefly, we stereotaxically implanted 7-8 weeks old C57Bl/6 mice with a bipolar insulated stainless-steel electrode in the left hippocampus, bilateral supra-dural cortical electrodes, and a cerebellar reference electrode. A week after the electrode implantation, we connected the animals to a video-EEG monitoring system and set stimulation intensity to twice the after-discharge threshold (ADT). We applied 10-sec stimulus trains followed by a 5 sec off period for 60 min. We injected mice intraperitoneally with BHB (1g/kg), oxamate (1g/kg), or saline 15 minutes after the development of autonomous seizure. We evaluated the duration and severity of EEG and its spectral analysis and scoring behavior on the Racine scale.

Results: Oxamate-treated mice had significantly shorter SE duration compared to saline-injected controls (median SE duration in saline- versus oxamate-treated mice: 263.5 and 63 minutes respectively; n = 5 each, p = 0.0233; Kaplan Meier curve, Gehan-Breslow-Wilcoxon test). Moreover, severe behavioral seizures (grades 4 and 5) were less frequent following oxamate injection. The oxamate-treated animals returned to normal behavior faster than control mice (n = 5 each, p = 0.0033, 2-tailed Mann-Whitney test). In addition to changes in behavioral manifestations, we detected changes in EEG with fewer high-frequency discharges and power EEG attenuation quickly following oxamate treatment. Similarly, SE duration in BHB-treated mice was significantly shorter than saline-injected mice (median SE duration in saline- versus BHB-treated mice: 240 and 100 minutes respectively p = 0.0289; n = 8 each; Kaplan Meier curve, Gehan-Breslow-Wilcoxon test). In addition, the median behavioral seizure scores were lower in the BHB-treated group when compared to saline-injected mice (n = 6 each, p=0.002; 2-tailed Mann-Whitney test). We observed a gradual attenuation of power EEG and high-frequency discharges along with seizure severity, which became less common in BHB-treated mice than control animals.

Conclusions: Targeting metabolic pathways by directly affecting the metabolite concentration (BHB) or enzyme activity (LDH) represents a promising strategy to treat SE. Ongoing studies explore these drugs’ effect on neuronal excitability.

Funding: Please list any funding that was received in support of this abstract.: R01 NS120945 & UVA Brain Institute.