Pharmacological characterisation of psilocybin and 5-MeO-DMT discriminative cues in the rat and their translational value for identifying novel psychedelics
Bibliographic record
Abstract
BACKGROUND AND AIMS: Drug discrimination procedures have made important contributions to the pre-clinical investigation of psychedelic drugs, such as psilocybin, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine (DMT) and 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). One of the most important being to highlight the critical role of central 5-HT2A receptor agonism as a mediator of hallucinogenic activity, and secondly, drugs that fully generalise to a 5-HT2A receptor agonist cued drug discrimination in rodents, may elicit hallucinogenic activity in humans, showing a forward translational value. However, there is relatively little information about how clinical exposures associated with hallucinations back-translate to generalisation profiles in the rat. METHODS: The present series of experiments utilised two cohorts of male Sprague-Dawley rats, one trained to a psilocybin (0.5 mg/kg SC) cue, and the second trained to a 5-MeO-DMT (1 mg/kg SC) cue. RESULTS: Tests of substitution and antagonism supported the primary role of 5-HT2A and 5-HT1A receptors, respectively, in the mediation of each cue. Plasma exposures of psilocin required for generalisation to the psilocybin cue (5-52 ng/mL) overlapped with clinical exposures associated with perceptual effects in humans. With respect to DMT and LSD, higher exposures were required in the rat compared to humans. Time-course studies using an approximate ED90 dose of each psychedelic showed differing temporal profiles in terms of duration of drug-lever generalisation, with LSD > psilocybin > 5-MeO-DMT ⩾ DMT, showing good agreement with clinical experience. With the exception of LSD, there was a good temporal association between plasma exposure and drug lever generalisation. The disconnect noted for LSD is mirrored by similar findings in the clinic. CONCLUSIONS: In summary, the present studies both support and extend the value of the drug discrimination assay as a translational approach to the pre-clinical study of psychedelic drugs.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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 source (direct Gemma or distilled Codex), 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".