Epigenetic mechanisms of rapid-acting antidepressants

Rapid-acting antidepressants, such as dissociative anesthetics, psychedelics, and empathogens, may improve psychiatric disorders by modulating neuroplasticity, neurotransmission, and immunity. Preliminary evidence suggests these drugs are accompanied by epigenetic changes—including alterations in DNA methylation, histone modifications, and non-coding RNA regulation—in stress-responsive brain regions, similar to those seen with conventional antidepressants. Whether these epigenetic changes causally contribute to therapeutic effects, are a consequence, or are unrelated remains unknown. Candidate mechanisms involve neuronal activity, serotonin and TRKB signaling, and direct interaction with chromatin. Causation, cell type-specificity, and mechanisms are largely unconfirmed.

Study at a glance

Abstract

BACKGROUND: Rapid-acting antidepressants (RAADs), including dissociative anesthetics, psychedelics, and empathogens, elicit rapid and sustained therapeutic improvements in psychiatric disorders by purportedly modulating neuroplasticity, neurotransmission, and immunity. These outcomes may be mediated by, or result in, an acute and/or sustained entrainment of epigenetic processes, which remodel chromatin structure and alter DNA accessibility to regulate gene expression. METHODS: In this perspective, we present an overview of the known mechanisms, knowledge gaps, and future directions surrounding the epigenetic effects of RAADs, with a focus on the regulation of stress-responsive DNA and brain regions, and on the comparison with conventional antidepressants. MAIN BODY: Preliminary correlative evidence indicates that administration of RAADs is accompanied by epigenetic effects which are similar to those elicited by conventional antidepressants. These include changes in DNA methylation, post-translational modifications of histones, and differential regulation of non-coding RNAs in stress-responsive chromatin areas involved in neurotrophism, neurotransmission, and immunomodulation, in stress-responsive brain regions. Whether these epigenetic changes causally contribute to the therapeutic effects of RAADs, are a consequence thereof, or are unrelated, remains unknown. Moreover, the potential cell type-specificity and mechanisms involved are yet to be fully elucidated. Candidate mechanisms include neuronal activity- and serotonin and Tropomyosine Receptor Kinase B (TRKB) signaling-mediated epigenetic changes, and direct interaction with DNA, histones, or chromatin remodeling complexes. CONCLUSION: Correlative evidence suggests that epigenetic changes induced by RAADs accompany therapeutic and side effects, although causation, mechanisms, and cell type-specificity remain largely unknown. Addressing these research gaps may lead to the development of novel neuroepigenetics-based precision therapeutics.