A Complex Impact of Systemically Administered 5-HT2A Receptor Ligands on Conditioned Fear
The International Journal of Neuropsychopharmacology July 5, 2021 Sven Melker Hagsäter, Robert Pettersson, Christopher Pettersson et al. 29 citations
Activating the 5-HT2A serotonin receptor with drugs such as psilocybin reduces conditioned fear in male rats, an effect blocked by a 5-HT2A inverse agonist. Inverse agonists alone did not change fear behavior, but they unmasked a fear-reducing effect of the SSRI escitalopram, which by itself had no effect. These results suggest that 5-HT2A receptor activation is not required for normal conditioned freezing but can dampen fear when over-activated. In the presence of an SSRI, the 5-HT2A receptor appears to oppose the anti-freezing effect of increased serotonin levels.