A metabolic switch in brain: glucose and lactate metabolism modulation by ascorbic acid

Area of Science:

• Neuroscience
• Cellular Metabolism
• Biochemistry

Background:

• Neurons primarily utilize glucose, but glial cells supply lactate during high synaptic activity.
• This energy coupling relies on astrocyte activation by glutamate and extracellular potassium.
• Neuronal metabolism faces a conflict between simultaneous glucose and lactate utilization due to pyruvate and NAD+/NADH levels.

Purpose of the Study:

• To review the novel function of ascorbic acid in brain energetics.
• To explore ascorbic acid's role as a metabolic switch modulating neuronal metabolism.
• To discuss the interplay of glucose, lactate, and ascorbic acid in neuronal energy supply.

Main Methods:

• Literature review focusing on brain energetics and metabolic pathways.
• Analysis of the proposed role of ascorbic acid in neuronal substrate utilization.
• Examination of the mechanisms of ascorbic acid release and uptake in the central nervous system.

Main Results:

• Ascorbic acid is highly concentrated in the CNS and released from astrocytes upon glutamate stimulation.
• Ascorbic acid influx into neurons inhibits glucose consumption and promotes lactate transport.
• This metabolic switch is facilitated by ascorbic acid flow between astrocytes and neurons, linked to vitamin C recycling.

Conclusions:

• Ascorbic acid plays a critical role in modulating neuronal metabolism, switching energy sources between rest and activation.
• This function is essential for efficient brain energetics, particularly during periods of high glutamatergic activity.
• Understanding ascorbic acid's role provides insights into brain energy metabolism and potential therapeutic targets.