Psilocybin is rapidly dephosphorylated in the body to psilocin, which is an agonist for several serotonin receptors, which are also known as 5-hydroxytryptamine (5-HT) receptors. In rats, psilocin binds with high affinity to 5-HT2A receptors and low affinity to 5-HT1 receptors, including 5-HT1A and 5-HT1D; effects are also mediated via 5-HT2C receptors. The psychotomimetic (mimicking the mind distortion present in psychosis) effects of psilocin can be blocked in a dose-dependent fashion by the 5-HT2A antagonist drug ketanserin. Various lines of evidence have shown that interactions with non-5-HT2 receptors also contribute to the subjective and behavioral effects of the drug. For example, psilocin indirectly increases the concentration of the neurotransmitter dopamine in the basal ganglia, and some psychotomimetic symptoms of psilocin are reduced by haloperidol, a non-selective dopamine receptor antagonist. Taken together, these suggest that there may be an indirect dopaminergic contribution to psilocin's psychotomimetic effects. Psilocybin and psilocin have no affinity for dopamine D2 receptor, unlike another common 5-HT receptor agonist, lysergic acid diethylamide (LSD). Psilocin antagonizes histamine H1 receptors with moderate affinity, compared to LSD which has lower affinity.
Psilocybin is rapidly dephosphorylated in the body to psilocin, which is an agonist for several serotonin receptors, which are also known as 5-hydroxytryptamine (5-HT) receptors. In rats, psilocin binds with high affinity to 5-HT2A receptors and low affinity to 5-HT1 receptors, including 5-HT1A and 5-HT1D; effects are also mediated via 5-HT2C receptors The psychotomimetic (mimicking the mind distortion present in psychosis) effects of psilocin can be blocked in a dose-dependent fashion by the 5-HT2A antagonist drug ketanserin Various lines of evidence have shown that interactions with non-5-HT2 receptors also contribute to the subjective and behavioral effects of the drug. For example, psilocin indirectly increases the concentration of the neurotransmitter dopamine in the basal ganglia, and some psychotomimetic symptoms of psilocin are reduced by haloperidol, a non-selective dopamine receptor antagonist. Taken together, these suggest that there may be an indirect dopaminergic contribution to psilocin's psychotomimetic effects. Psilocybin and psilocin have no affinity for dopamine D2 receptor, unlike another common 5-HT receptor agonist, lysergic acid diethylamide (LSD) Psilocin antagonizes histamine H1 receptors with moderate affinity, compared to LSD which has lower affinity.