Psychedelic drugs like LSD, mescaline, and psilocybin are gaining renewed scientific and clinical interest due to the need for new mental health treatments, progress in research, and changing drug policies. The FDA's designation of psilocybin as a "Breakthrough Therapy" for treatment-resistant depression has opened a path for these drugs to be used in clinical settings. However, a clearer understanding of how these drugs work at the molecular level is essential for developing such applications. This review examines current knowledge about the molecular details of psychedelic drug actions and suggests that these discoveries can provide new insights into their hallucinogenic and therapeutic mechanisms.
Psychedelic drugs such as LSD and psilocybin show promise as treatments for depression, anxiety, PTSD, migraine, and cluster headaches by activating the 5-HT2A receptor (HTR2A). Researchers engineered several new mouse lines to study the role of HTR2A and the neurons that express it. One line allows visualization of the receptor and identification of HTR2A-containing cells, providing a detailed anatomical map. Another line has a humanized version of the receptor, and a third enables targeted genetic manipulation. The mice exhibited expected behavioral responses to psychedelics, confirming their usefulness. Electrophysiology showed that serotonin increases firing of specific pyramidal neurons through HTR2A, consistent with the receptor's location on the cell surface. These tools will help clarify how psychedelics work at molecular, cellular, and behavioral levels.