The dual dopamine‐glutamate phenotype of growing mesencephalic neurons regresses in mature rat brain
Bibliographic record
Abstract
Coexpression of tyrosine hydroxylase (TH) and vesicular glutamate transporter 2 (VGLUT2) mRNAs in the ventral tegmental area (VTA) and colocalization of these proteins in axon terminals of the nucleus accumbens (nAcb) have recently been demonstrated in immature (15-day-old) rat. After neonatal 6-hydroxydopamine (6-OHDA) lesion, the proportion of VTA neurons expressing both mRNAs and of nAcb terminals displaying the two proteins was enhanced. To determine the fate of this dual phenotype in adults, double in situ hybridization and dual immunolabeling for TH and VGLUT2 were performed in 90-day-old rats subjected or not to the neonatal 6-OHDA lesion. Very few neurons expressed both mRNAs in the VTA and substantia nigra (SN) of P90 rats, even after neonatal 6-OHDA. Dually immunolabeled terminals were no longer found in the nAcb of normal P90 rats and were exceedingly rare in the nAcb of 6-OHDA-lesioned rats, although they had represented 28% and 37% of all TH terminals at P15. Similarly, 17% of all TH terminals in normal neostriatum and 46% in the dopamine neoinnervation of SN in 6-OHDA-lesioned rats were also immunoreactive for VGLUT2 at P15, but none at P90. In these three regions, all dually labeled terminals made synapse, in contradistinction to those immunolabeled for only TH or VGLUT2 at P15. These results suggest a regression of the VGLUT2 phenotype of dopamine neurons with age, following normal development, lesion, or sprouting after injury, and a role for glutamate in the establishment of synapses by these neurons.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| 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".