Monocarboxylates (pyruvate and lactate) as alternative energy substrates for the induction of long-term potentiation in rat hippocampal slices

We previously reported that mild hypoglycemic conditions hamper the induction of long-term potentiation (LTP) in the CA1 region of rat hippocampal slices. In the present study, we examined whether monocarboxylates (pyruvate and lactate) permit LTP induction when glucose is unavailable. During glucose deprivation, pyruvate and lactate not only maintained basal synaptic transmission but also allowed LTP induction, with pyruvate being more effective than lactate. Additionally, LTP inhibition by 5 μM iodoacetate, a glycolytic inhibitor, was prevented by addition of pyruvate but not lactate. These results suggest that monocarboxylates can be effective alternative energy substrates for LTP induction when glucose is not available. However, lactate and pyruvate are not identical as energy sources for LTP induction.