Glutamine as an energy substrate in cultured neurons during glucose deprivation
Bibliographic record
Abstract
During glucose deprivation an increase in aspartate formation from glutamine has been observed in different brain preparations, including synaptosomes and cultured astrocytes. To what extent this reaction, which provides a substantial amount of energy, occurs in different types of neurons is unknown. The present study shows that (14)CO(2) formation from [U-(14)C]glutamine in cerebellar granule neurons, a glutamatergic preparation, increased by 60% during glucose deprivation, indicating enhanced aspartate formation or increased complete oxidative degradation of glutamine. In primary cultures of cerebrocortical interneurons, a GABAergic preparation, the rate of (14)CO(2) production from [U-(14) C] glutamine was four times lower and not stimulated by glucose deprivation. During incubation with glutamine (0.8 mM) as the only metabolic substrate, cerebellar granule cells maintained an oxygen consumption rate of 12 nmol/min/mg protein, corresponding to an aspartate formation of 8 nmol/min/mg protein (three oxidations occur between glutamine and aspartate) or to a total oxidative degradation of 3 nmol/min/mg protein. During glucose deprivation, the rate of aspartate formation increased, and during a 20-min incubation in phosphate-buffered saline it amounted to 3.3 nmol/min/mg protein at 0.2 mM glutamine, which might have been more if measured at 0.8 mM glutamine. These values are consistent with the rate of glutamine utilization calculated based on oxygen consumption and leaves open the possibility that some glutamine is completely degraded oxidatively, as has been shown by other authors based on pyruvate recycling and labeling of lactate from aspartate in cerebellar granule neurons.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".