In vitro and in vivo comparison of [<sup>3</sup>H](+)‐PHNO and [<sup>3</sup>H]raclopride binding to rat striatum and lobes 9 and 10 of the cerebellum: A method to distinguish dopamine D<sub>3</sub>from D<sub>2</sub>receptor sites: A method to distinguish dopamine D<sub>3</sub>from D<sub>2</sub>receptor sites
Why this work is in the frame
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Bibliographic record
Abstract
In vitro binding characteristics of the dopamine D₃/D₂ antagonist [³H]raclopride were compared to the D₃/D₂ agonist [³H](+)-PHNO in membrane preparations from rat striatum, cerebellum Lobules 9 and 10 (CB L9,10), and other cerebellar regions. In striatum, both radioligands labeled a single binding site. [³H](+)-PHNO showed higher affinity, though lower B(max) , compared with [³H]raclopride and was sensitive to inhibition by Gpp(NH)p. [³H](+)-PHNO showed significant specific binding to CB L9,10 membranes with higher affinity compared to striatal membranes. [³H](+)-PHNO binds to a high- and a low-affinity binding site in CB L9,10 membranes; the high-affinity site was not Gpp(NH)p-sensitive. [³H](+)-PHNO did not significantly bind cerebellum left hemisphere membranes. Very low specific binding of [³H]raclopride was found in CB L9,10. The selective dopamine D₃ antagonist SB-277011 did not displace the binding of either ligand to striatal membranes but potently inhibited the binding of [³H](+)-PHNO in CB L9,10 membranes. The highly selective D₂ antagonist SV-156 showed the opposite profile. In vivo experiments were consistent with and supported by in vitro results. In summary, [³H](+)-PHNO and [³H]raclopride mainly label dopamine D₂ receptors in rat striatum, with [³H](+)-PHNO labeling a D₂(High) population. In vitro and in vivo, [³H](+)-PHNO labels CB L9,10 dopamine D₃ receptors that are apparently in a high affinity state whereas [³H]raclopride gave only very low signal in this region. The present approaches appear useful for selectively labeling dopamine D₃ and D₂ receptors in different rat brain regions and offer the possibility to demonstrate D₃ versus D₂ receptor selectivity of compounds using native rat brain tissue.
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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 | 0.003 | 0.008 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.004 | 0.000 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 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 it