Mapping excitatory synaptic plasticity evoked by single-dose psilocybin in mice

A single dose of psilocybin can induce long-lasting antidepressant effects. The neurobiological mechanisms underlying such sustained antidepressant effect remain insufficiently understood, particularly at the level of synaptic function and drug-target specificity. Here, we aimed to delineate single-dose psilocybin-induced excitatory synaptic plasticity. Synaptic plasticity was assessed by whole-cell patch-clamp recording of excitatory synaptic transmission 24 h after treating mice with single-dose psilocybin. We correlated the recordings with transcriptomics data and used a conditional single-vector CRISPR/SaCas9-dependent knock-out strategy to validate the role of the 5-HT _2A receptor. Psilocybin selectively increased the frequency of miniature excitatory postsynaptic currents in specific cortical sub-regions and in the amygdala. Frequency correlated with the expression levels of psilocin-targeted serotonin receptors, when expression heterogeneity between cortical subregions and along the anterior-posterior axis was accounted for. Post-synaptic Htr2a knock-out in the insular/orbitofrontal cortex precluded psilocybin-induced 24-h plasticity. These findings demonstrate that lasting psilocybin-induced effects on excitatory synaptic transmission manifest with brain-region specificity, likely reflecting a functional consequence of synapse formation. This work establishes a foundation for a circuit-specific, mechanistic understanding of functional aspects of psilocybin-induced neuroplasticity.