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Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine, PSOP) was first isolated from Psilocybe mexicana, a mushroom from Central America by Albert Hofmann in 1957 and soon after produced synthetically in 1958 (Hofmann et al. 1958a, b). PSOP is an indole hallucinogen with potential clinical applications in the treatment for anxiety disorders, obsessive–compulsive disorder, major depression and cluster headaches (Moreno et al. 2006; Grob et al. 2011; Young 2013). PSOP is dephosphorylated in the body and converted into the active metabolite psilocin (4-hydroxy-N,N-dimethyltryptamine) which exerts psychoactive effects by altering neurotransmission through serotonin (5-HT) receptors 5-HT1A, 5-HT1D, 5-HT2A and 5-HT2C, but binds to 5-HT2A receptors with high affinity (Ki = 6 nM) (McKenna et al. 1990; Passie et al. 2002). 5-HT2A receptors are highly expressed throughout the hippocampus (HPC) in the dentate gyrus (DG), hilus, cornu ammonis (CA) 1 and CA3 and are colocalized on GABAergic neurons, pyramidal and granular cells