Towards Simplification of Ketogenic Diet in Epilepsy: Effect of Caprylic (C8) and Capric (C10) Acid on the Mitochondrial Respiratory Chain in Murine Hippocampal Neurons In Vitro

BACKGROUND: Pharmacotherapy is the therapeutic mainstay in epilepsy, but in about 30% of patients, the epilepsy is pharmacoresistant. A ketogenic diet (KD) is an alternative therapeutic option. The mechanisms underlying the anti-seizure effect of KD are not fully understood. An enhanced energy metabolism may have a protective effect; C8 and C10 fatty acids were previously shown to activate mitochondrial function in vitro. In the present study, we investigated whether ß-hydroxybutyrate (HOB), C8, C10 or a combination of C8 and C10 fatty acids, which all increase under KD, could activate mitochondrial respiratory chain enzymes in murine hippocampal neurons (HT22). METHODS: Cells were incubated for one week in the presence of the different metabolites. Respiratory chain enzyme activities as well as citrate synthase as a mitochondrial marker enzyme were determined spectrophotometrically in these cells. We observed that enzyme activities of complexes I and III, II and III, and IV (cytochrome c-oxidase) and V (ATP synthase) significantly increased in response to incubation with C8 and C10 fatty acids and a combination of both. RESULTS: This activation of the respiratory chain enzymes was not inferior to an incubation with HOB, the key metabolite in KD. The activity of the mitochondrial marker enzyme citrate synthase increased under incubation with the fatty acids, showing that the mitochondrial content increased. CONCLUSIONS: In murine hippocampal cells, C8, C10 and combined C8 and C10 fatty acids led to variable increases in activities of mitochondrial respiratory chain enzymes and citrate synthase. This indicates that both C8 and C10 fatty acids may be important for the antiepileptic effect of KD, as they enhance energy production.