Introduction: Neurons have a very high energy requirement, and their metabolism is tightly regulated to ensure delivery of adequate substrate to sustain neuronal activity and neuroplastic changes. The mechanisms underlying the regulation of neuronal metabolism, however, are not completely clear.
Objective: The objective of this study was to investigate the central carbon metabolism in neurons, in order to identify the regulatory pathways governing neuronal anabolism and catabolism.
Methods: Here we first have applied MS-based endometabolomics to elucidate the metabolic dynamics in cultured hippocampal primary neurons. Using nanoLC-ESI-LTQ Orbitrap MS approach followed by statistical analysis, we measure the dynamics of uniformly labeled 13C-glucose entering neurons. We adapted the method by coupling offline patch-clamp setup with MS to confirm findings in vivo.
Results: According to non-parametric statistical analysis of metabolic dynamics, in cultured hippocampal neurons, the glycerol phosphate shuttle is active and correlates with the metabolic flux in the pentose phosphate pathway. In the hippocampus, glycerol-3-phosphate biosynthesis was activated in response to long-term potentiation together with the upregulation of glycolysis and the TCA cycle, but was inactive or silenced in basal conditions.
Conclusions: We identified the biosynthesis of glycerol-3-phosphate as a key regulator in mechanisms implicated in learning and memory. Notably, defects in enzymes linked with the glycerol phosphate shuttle have been implicated in neurological disorders and intellectual disability. These results could improve our understanding of the general mechanisms of learning and memory and facilitate the development of novel therapies for metabolic disorders linked with intellectual disability.
Keywords: Glucose metabolism; Glycerol phosphate; Hippocampus; Long term potentiation; Mass spectrometry; Primary neurons.