Major sources of energy for the brain depend on species, age, and physiological conditions

How the exceptional energy demands of the brain are met.

• In addition to glucose, other substrates must be considered along with fuel interactions, metabolic challenges, and cerebral maturation. (1)
• Ketone bodies are major metabolic fuels of the brain of the suckling rat under normal conditions. (2)
• Ketone bodies can represent about 30–70% of the total energy metabolism balance of the immature rat brain.(3)
• Lactate is an important metabolic substrate for the brain...and plays a crucial role in brain development... Once the onset of suckling takes place, however, ketone bodies become the major fuel for brain development.(4)
• 70% of the cerebral metabolic requirements were met by lactate in animals aged 6 days. At 15 days of age, glucose, 3-hydroxybutyrate, and lactate supply 58%, 19%, and 23% of the brain's fuel requirement, respectively.(5)

Sources:

1. Prins, M. L. (2008) J Cereb Blood Flow Metab, 28, 1-16.

2. Hawkins, R. A., Williamson, D. H. and Krebs, H. A. (1971) Biochem J, 122, 13-18.

3. Nehlig, A. (2004) Prostaglandins Leukot Essent Fatty Acids, 70, 265-275.

4. Medina, J. M. and Tabernero, A. (2005) J Neurosci Res, 79, 2-10.

5. Dombrowski, G. J., Jr., Swiatek, K. R. and Chao, K. L. (1989) Neurochem Res, 14, 667-675.

Not only ketone bodies: on neuroprotective effects of energy substrates

In the previous post On the mechanisms of brain protection by ketones, it was described how a shortage of ketones caused pathological changes in brain cells resulting in abnormal behavior of GABA, the principal brain chemical helping to resist hyperactivity. In the second article, the authors showed that not only ketone bodies, but also other energy carriers such as lactate and pyruvate (or their shortages) can make all the difference between smoothly functioning brain networks and pathologically overly excited ones.

"We suggest that metabolic deficits induce changes in intrinsic neuronal properties resulting in hyperactivity in single neurons and aberrant neuronal network behavior. This hyperactivity in turn increases neuronal energy demands, which cannot be met due to metabolic pathologies and a vicious cycle occurs. Our hypothesis predicts that the adequate delivery of energy substrates may interrupt this pathological spiral of events and provide therapeutic options targeting the cause of pathologies rather than their symptoms" concluded the authors.

Source:

Holmgren CD, Mukhtarov M, Malkov AE, Popova IY, Bregestovski P, Zilberter Y.. Energy substrate availability as a determinant of neuronal resting potential, GABA signaling and spontaneous network activity in the neonatal cortex in vitro. J Neurochem. 2009 Nov 24.