Study links psilocybin receptor activation to sustained structural brain changes

Psilocybin receptor activation is linked to sustained structural brain changes that could help explain long-lasting antidepressant effects. In a mouse study led by Connor J. Maltby, researchers dosed psilocybin and measured 5-HT2A receptor occupancy in the prefrontal cortex alongside acute psychedelic activity (head twitch response). Head twitch magnitude showed an inverted-U relationship, with stronger effects at intermediate receptor activation levels and reduced responses at higher doses. When animals were tested 20 to 24 hours later, psilocybin-treated mice showed behavioral patterns consistent with reduced anxiety-like behavior (elevated zero maze) and antidepressant-like effects (forced swim test). At the cellular level, psilocybin shifted molecular markers of microtubule dynamics toward a more flexible, dynamic state in both the prefrontal cortex and the amygdala, and increased expression of synaptic proteins tied to neuroplasticity selectively in the prefrontal cortex but not the amygdala, which the team hypothesizes may help rewire depression-related circuits while limiting hardwiring of fear-based connections.