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Q: Hi Tanya,

It’s Ingrid again, amused by my beloved topic of excitatory GABA, this time, at SFN 2010. I’m not fortunate enough to be there but nice guys
posted some posters’ photos on our itranet.

My two questions are:

1. Why in table 1, they give SERUM levels of BHB, pyruvate and lactate although the discussion is going on around neuronal behavior?!  Looks
just plane and simple illiterate!

2. Conclusion reads: “Therefore, conventional glucose containing ACSF provides adequate energy supply in vitro.” Do they forgot or
intentionally omitted mentioning immature brain?  A renown expert in developmental metabolism, Dr. Nehlig, one of the coauthors, is it
possible that she agrees with this conclusion, namely that in neonatal slices, neurons happily run on glucose – or this conclusion does not
relate to immature neurons? If so, what this poster is about other than attempting to scandalize Dr. Zilberter team and work?

Thank you Tanya for your time and patience with us inpatient students

Ingrid

A: Dear Ingrid,

Remembering your previous question on this topic ,  I guess it’s about Dr Ben-Ari poster, right? I  saw this poster’s photo.

Let’s see how to politely answer your questions. It’s a simple “I have no idea” to your question number 1. You might want to read what surrounds neurons in real brain including energy substrate concentrations in our TIPS review (1), but why SERUM [my capitals] fascinates the authors more than ECF is an enigma to me as it is to you (2).

As to the question number 2, your hypothesis is very interesting although does not help me to answer. Indeed, in all articles by Dr. y Zilberter’s team, works of Dr Nehlig are respectfully and consistently referred to. An example from the Tips review: “Once the onset of suckling takes place, KB become the major fuel for rat brain development” (3) and “In the postnatal developing rat brain, glucose utilization is limited to only about 20% of adult levels” (4).

Notwithstanding, as you quote from the SFN poster, “Therefore, conventional glucose containing ACSF provides adequate energy supply in vitro” –  certainly it cannot be about immature brain. But the title clearly reads: “Depolarizing action of GABA in hippocampal and neocortical IMMATURE [my capitals] neurons depends neither on ketone bodies nor on pyruvate/lactate”. I’m lost here. Sorry I failed!

References

1. Trends Pharmacol Sci. 2010 Sep;31(9):394-401
2. Barriers and fluids that connect and divide blood, brain, and neurons
3. A. Nehlig, Brain uptake and metabolism of ketone bodies in animal models, Prostaglandins Leukot. Essent. Fatty Acids 70 (2004), pp. 265–275
4. A. Nehlig et al., Quantitative autoradiographic measurement of local cerebral glucose utilization in freely moving rats during postnatal development, J. Neurosci. 8 (1988), pp. 2321–2333