Psychedelics such as psilocybin are known for their hallucinogenic properties and have also been reported to produce long-lasting therapeutic effects in depression and possibly also other psychiatric disorders. Several lines of evidence suggest that psilocybin exerts its effects through activation of 5-HT2A receptors located postsynaptically to serotonergic neurons, e.g., in the frontal cortex, parts of the limbic system, including the amygdala and hippocampus, and striatum. The present study was conducted to shed further light on psilocybin-induced changes in gene expression.

Samples from the medial prefrontal cortex, cingulate cortex, hippocampus, amygdala, and striatum were collected from 24 male Wistar rats 90 minutes after they had been injected with either saline or psilocybin (2 mg/kg) and subjected to multi-region transcriptional profiling using 3prime-RNASeq technology.

Nfkbia and Sgk1 were upregulated in all the studied regions, Ddit4 was upregulated in four regions, and Gpd1, Apold1, Sox9, Tsc22d3, and Slc2a1 were differentially expressed in two regions. Other cases of differentially expressed genes were region-specific.

Whereas psilocybin was not found to alter the expression of genes encoding enzymes, transporters, or receptors implicated in the serotonergic signaling, or those specifically involved in the regulation of the synaptic activity of other neurotransmitters, a common denominator for many of the genes impacted by psilocybin is that they have previously been found to be activated by glucocorticoids.