MicroRNAs underlying the antidepressant effect of psilocybin - Establishing an nCounter pipeline for microRNA-quantification in the pig brain

Abstract Novel treatment strategies are needed to overcome some of the current challenges related to treatment resistance and treatment latency within the psychiatric field. Recently, psilocybin has shown promise as a novel treatment of major depressive disorder. A single dose of psilocybin is associated with lasting changes in personality and mood. In parallel, various studies have indicated that microRNAs (miRNAs) are regulated after antidepressive interventions. Here, pigs were used to study the transcriptional profiles of miRNAs in the prefrontal cortex (PFC) and hippocampus (HIP), 1 day and 1 week after a single dose of psilocybin. A streamlined process was developed to adapt the Nanostring nCounter technology, specifically the Human v3b miRNA Assay panel, for compatibility with pig tissue samples. The mirmachine tool was used to select miRNAs with complete human-pig sequence conservation to make a conservative reannotation of pig microRNAs. Furthermore, different normalization strategies were employed. Utilizing this pipeline, dysregulation of 12 miRNAs in the PFC and 2 miRNAs in the HIP was ∂identified 1 day after psilocybin administration. Seven days after psilocybin administration, only 4 dysregulated miRNAs were observed in the HIP. Among the 18 identified miRNAs, 9 have previously been linked to depression. Notably, miR-212-3p and miR-107 displayed robust acute regulation across all four normalization strategies in the PFC. The two miRNAs are known to exert anti-inflammatory effects, mirroring previously reported effects of psilocybin. These results suggest that psilocybin may exert its acute and sustained molecular effects through the regulation of specific miRNAs in core brain areas of depression.