Activation of serotonin 2A receptors (5-HT2ARs) is essential for tryptamine-based psychedelics to produce antidepressant-like effects in rodents. While hallucinogenic properties are generally attributed to 5-HT2AR activation, it was unclear whether these receptors also mediate antidepressant effects, especially because some nonhallucinogenic analogues show antidepressant-like properties. Using pharmacological and genetic tools, the authors demonstrate that 5-HT2AR activation is required for the antidepressant-like effects of tryptamine psychedelics, suggesting that hallucinogenic and therapeutic effects can arise through the same receptor.
A general chemical synthesis method for tropane alkaloids—compounds with a characteristic 8-azabicyclo[3.2.1]octane core—enables late-stage structural diversification at positions N8, C3, C6, and C7, which are important for biological activity. The approach constructs the core via aziridination of a cycloheptadiene intermediate followed by vinyl aziridine rearrangement, yielding six tropane alkaloids and several analogues in 5-7 steps. Testing five tropane-containing compounds in cultured cortical neurons for dendritic spine growth—a marker of structural neuroplasticity—suggests that the orientation of the C3 substituent may influence psychoplastogenic effects. This platform supports future structure-activity relationship studies.
Tropane-containing small molecules such as scopolamine can promote neuronal growth (psychoplastogens) but also block all muscarinic receptor subtypes, causing unwanted anticholinergic side effects. Researchers conducted phenotypic structure-activity relationship studies on various tropane subclasses to separate these effects. They identified several novel tropanes that substantially increase cortical neuron growth while showing much weaker activity at all muscarinic receptor subtypes than scopolamine, suggesting that the neuroplasticity-promoting and muscarinic-blocking properties can be decoupled.