Oral <scp>D</scp>‐amphetamine causes prolonged displacement of [<sup>11</sup>C]raclopride as measured by PET
Why this work is in the frame
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Bibliographic record
Abstract
Parenterally administered D-amphetamine has been used as a challenge drug to release dopamine, which in turns inhibits [11C]raclopride binding to dopaminergic D2 receptors as measured using positron emission tomography (PET) techniques. The primary objective of this study was to determine whether orally administered D-amphetamine would inhibit [11C]raclopride binding in a manner similar to that produced by intravenously administered D-amphetamine. The secondary objective was to assess the timeline of these effects. Twelve healthy human volunteers participated in this study. Subjects were scanned at baseline and 2 h after D-amphetamine administration (n = 5); at baseline, 2 and 6 h postdrug (n = 4); or at baseline, 2 and 24 h postdrug (n = 3). Orally administered D-amphetamine caused a significant decrease in [11C]raclopride binding at 2 h (13% +/- 5%). Receptor availability was still decreased at 6 h (18% +/- 6%), even though physiological effects had completely returned to baseline. [11C]Raclopride binding returned to baseline at 24 h. The percentage of [11C]raclopride displacement was not correlated with plasma D-amphetamine concentrations. In conclusion, orally administered D-amphetamine caused a reliable and prolonged [11C]raclopride displacement, the magnitude of which is similar to that observed after intravenous administration. Possible mechanisms for the observed prolonged displacement may include persistence of intrasynaptic dopamine and/or receptor internalization.
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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 | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it