The serotonergic psychedelic DOI reduces anxiety-like behavior by activating 5-HT2A receptors on fast-spiking parvalbumin (PV)-positive interneurons in the CA1/subiculum region of the ventral hippocampus. Experiments combining anatomical, pharmacological, and genetic methods showed that these receptors are necessary for the anxiolytic effect. In vivo recordings revealed that DOI increases the firing rate of PV-positive interneurons, most of which express 5-HT2A receptors. Restoring 5-HT2A receptors specifically in PV-positive cells in a loss-of-function background reinstated DOI's anxiety-relieving effects, identifying these interneurons as a cellular trigger for psychedelic-induced relief of anxiety-like behavior.
Serotonergic psychedelics show therapeutic effects across diverse neuropsychiatric, inflammatory, and cardiometabolic disorders, effects mediated largely by the serotonin 5-HT2A receptor. These drugs are exceptionally context-dependent, able to be anti-inflammatory or pro-inflammatory depending on setting. Each target pathology is linked to elevated stress exposure, which drives mitochondrial and allostatic dysregulation. The authors propose that psychedelics act as super-normal stimuli for the adaptive 5-HT2A receptor stress response, inducing a process called allostatic recalibration (AR). AR involves three phases: destabilizing, recalibrating, and consolidating updated allostatic programs. This recalibration replaces entrenched pathological allostatic programs with ones tuned to the safe context of psychedelic therapy, explaining their transdiagnostic effects.