The structural diversity of psychedelic drug actions revealed.

There is currently a resurgence in exploring the utility of classical psychedelics to treat depression, addiction, anxiety disorders, cluster headaches, and many other neuropsychiatric disorders. A biological target of these compounds, and a hypothesized target for their therapeutic actions, is the 5-HT serotonin receptor. Here, we present 7 cryo-EM structures covering all major compound classes of psychedelic and non-psychedelic agonists, including a β-arrestin-biased compound RS130-180. Identifying the molecular interactions between various psychedelics and the 5-HT receptor reveals both common and distinct motifs among the examined psychedelic chemotypes. These findings lead to a broader mechanistic understanding of 5-HT activation, which can catalyze the development of novel chemotypes with potential therapeutic utility and fewer side effects.