It is a well-known "fact" that under normal conditions glucose is responsible for providing almost all the energy needed by the healthy brain. However, it is not at all clear why that should be so: after all, fatty acids are well known to cross the brain-blood barrier. Why souldn't they be substrates for beta-oxidation in neurons? After browsing the literature, I still do not have an answer for that question. The Gene Expression Database reports that the enzymes involved in beta-oxidation are indded expressed in brain, but it is not clear if the data are from tissue homogeneates ot form purified neurons/astrocytes, etc. Back in 1993, Ebert et al. showed that ca. 20% of the brain's energy needs may be met by medium-chain fatty acids. Drawing on earlier research by other authors, Ebert et al. concluded that astrocytes probably account for the fatty acids oxidation, while the neurons survive on glucose alone (or a mixture of glucose and lactate provided by the astrocytes themselves).
I would still like to find out any explanation for the neurons' dependence on glucose (or glucose/lactate).. Any ideas?
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ReplyDeletenice article. thanks for sharing sir. i think brain metabolism is very interesting topic. please give more info. thank you
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