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 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".