Our response to the suggestion of Drs Morelli and Panfoli that myelin can carry out oxidative phosphorylation has been published as Harris, J.J. & Attwell, D. (2012) Is myelin a mitochondrion? Journal of Cerebral Blood Flow and Metabolism, advance online publication available at doi: 10.1038/jcbfm.2012.148
In addition, contrary to the statement by Drs Morelli and Panfoli, the notion that myelinated optic ner...
Our response to the suggestion of Drs Morelli and Panfoli that myelin can carry out oxidative phosphorylation has been published as Harris, J.J. & Attwell, D. (2012) Is myelin a mitochondrion? Journal of Cerebral Blood Flow and Metabolism, advance online publication available at doi: 10.1038/jcbfm.2012.148
In addition, contrary to the statement by Drs Morelli and Panfoli, the notion that myelinated optic nerve axons use 23% of the ATP consumed by smaller, unmyelinated optic nerve axons was not an a priori assumption; it was, as stated even in the sentence that they quoted, a prediction of our model.
None declared
The paper from Harris and Attwell is of interest, but it does not mention a new vision of energetic supply for the axon, centered on the ability of the myelin sheath to conduct an aerobic metabolism (Morelli et al., 2011), that contributes to axonal metabolism (Ravera et al., 2009). In view of the immensity of what is unclear or unknown about neuroenergetics, our recent hypothesis considers the implications of Heme synth...
The paper from Harris and Attwell is of interest, but it does not mention a new vision of energetic supply for the axon, centered on the ability of the myelin sheath to conduct an aerobic metabolism (Morelli et al., 2011), that contributes to axonal metabolism (Ravera et al., 2009). In view of the immensity of what is unclear or unknown about neuroenergetics, our recent hypothesis considers the implications of Heme synthesis in myelin (Morelli et al, 2012). The calculation made by the authors of the energy budget for the myelinated axon stands for myelin reducing the cost of the action potential, but to this end the authors assume that: "Per action potential, each myelinated axon was predicted to use 23% of the ATP consumed by each (smaller) unmyelinated axon", an a priori condition. Nevertheless, the authors could not exclude the possibility that some ATP production is driven by metabolic cooperation with glia: "..necessary to posit metabolic support from myelin to provide sufficient substrate for this level of ATP production", a currently supported opinion (Fields, 2010).
References
Morelli A, Ravera S, Panfoli I.(2011) Hypothesis of an energetic function for myelin. Cell Biochem Biophys 61:179-87.
Ravera S, Panfoli I, Calzia D, et al. (2009) Evidence for aerobic ATP synthesis in isolated myelin vesicles. Int J Biochem Cell Biol 41:1581-91.
Morelli A, Ravera S, Calzia D, Panfoli I.(2012) Impairment of heme synthesis in myelin as potential trigger of multiple sclerosis. Med Hypotheses. Mar 6.
Fields R D. (2012) Neuroscience. Change in the brain's white matter. Science 330:768-9.