Heightened locomotor‐activating effects of amphetamine administered into the nucleus accumbens in adolescent rats
Bibliographic record
Abstract
There is a shift in sensitivity to systemically administered psychostimulants in adolescence, as evidenced by less amphetamine-induced locomotor activity in adolescent compared to adult rodents. Locomotor activating effects of amphetamine are dependent on drug actions in the core of the nucleus accumbens (NAc), but the contribution of this region to age differences in amphetamine sensitivity has not been studied directly. In the present study, we investigated the development of the NAc using targeted injections of amphetamine (0, 3, or 6 μg/side) directly into the NAc core in early (postnatal day 30; P30) or late (P45) adolescence, or in adulthood (P75). Locomotor activity was recorded during two 1h sessions, 48 h apart. Amphetamine increased locomotor activity at all ages. P45 rats were more active than adults only at the 3 μg/side dose, but this difference was not significant when baseline activity was taken into account. In contrast, P30 rats were more active than adults at the 6 μg/side dose, indicating that the magnitude of the locomotor response is highest in early adolescence. Results of the present study are the first to directly show a developmental difference in the sensitivity of the NAc to amphetamine under conditions in which the influence of pharmacokinetic factors and regulatory brain regions is minimized.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 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".