Functional and immunocytochemical characterization of D‐serine transporters in cortical neuron and astrocyte cultures
Bibliographic record
Abstract
D-serine is an endogenous coagonist of N-methyl-D-aspartate (NMDA) receptors that plays an important role in synaptic function, neuronal development, and excitotoxicity. Mechanisms of D-serine transport are important in regulation of extracellular D-serine concentration and therefore of these critical processes. D-serine can be transported with low affinity through the Na(+)-dependent amino acid transporter termed ASCT2, whereas high-affinity D-serine uptake has been reported through the Na(+)-independent transporter termed asc-1. We investigated immunoreactivity for ASCT2 and asc-1 and D-serine transport kinetics in cultured cortical neurons and astrocytes to gain insight into how D-serine transporters regulate CNS D-serine levels. Both neurons and astrocytes exhibited low-affinity Na(+)-dependent D-serine uptake (K(T) > 1 mM) with broad substrate selectivity that was consistent with uptake through ASCT2. Both neurons and astrocytes also stained positively for ASCT2 in immunocytochemistry studies. Neurons but not astrocytes stained positively for the high-affinity D-serine transporter asc-1, but no evidence of functional asc-1 could be detected in neurons with conditions that produced such activity in cortical synaptosomes. These data support ASCT2 function in both neuron and astrocyte cultures and identify a discrepancy between observed asc-1 immunoreactivity and lack of functional asc-1 activity in neuron cultures. Together these findings further our knowledge of the processes that govern D-serine regulation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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 teacher head, 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".