A multi-institutional investigation of psilocybin's effects on mouse behavior.

Psilocybin (2 mg kg−1, intraperitoneally) robustly and replicably increases anxiety- and avoidance-related behaviors and decreases fear expression in mice across five independent laboratories.

• Why it matters: Rapidly emerging mouse studies on psychedelics leave uncertainty about which behavioral effects are reproducible and reliable across settings.
• What they did: Five labs ran the same acute and 24 h post-dose behavioral tests in ~200 male and female mice per experiment, using psilocybin 2 mg kg−1 intraperitoneally.
• The result: Effects were not replicable 24 h later for reducing anxiety- and depression-like behaviors or facilitating fear extinction, and there were no psilocybin-linked changes in social preference or social reward learning.

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