Psilocybin induces stereotyped movements and reduces defensive responding in planarians through 5-hydroxytryptamine mechanisms.
Behav Pharmacol July 1, 2026 Razeen J. Akbar, Amy D. Stringer, Sonita Wiah et al.
Psilocybin, a psychedelic compound, causes repetitive, stereotyped movements and reduces defensive reactions in planarian flatworms. These effects are mediated by the neurotransmitter serotonin (5-hydroxytryptamine). The findings suggest that psilocybin's behavioral actions in this simple animal model are linked to serotonergic signaling.