A study done by the Rockefeller Institute examined the effect of psilocybin, psilocin, and serotonin on rat uterus and stomach tissue strips. In the study, psilocybin and psilocin had a serotonin-like effect if they caused contraction of the tissue. The researchers found psilocybin and psilocin acted like serotonin but displayed anti-serotonin activity as the concentration increased. Psilocin had more potent anti-serotonin activity than psilocybin.
Study Finds Psilocybin and Psilocin Have Serotonin-Like and Anti-Serotonin Activity
Researchers find psilocybin and psilocin sometimes act like serotonin but act against it at higher concentrations.