The sigma-1 receptor: a mechanistically-informed therapeutic target for antidepressants.
Naomi Xiao, Liyang Yin, Kayla M Teopiz, Angela T H Kwan, Gia Han Le, Sabrina Wong, Kyle Valentino, Hayun Choi, Joshua D Rosenblat, Roger Ho, Serene Lee, Roger S McIntyre
Expert opinion on therapeutic targets June 1, 2025 DOI: 10.1080/14728222.2025.2500424 via PubMed
Summary
AI-generated from the abstractSigma-1 receptors (S1Rs) may be a target and mediator of antidepressant activity. They regulate neurotransmitter release (including monoamines and glutamate), influence intracellular calcium levels, and affect immune inflammatory responses. In August 2022, the FDA approved dextromethorphan-bupropion, the first antidepressant whose hypothesized mechanism includes activity at S1Rs. The review synthesizes preclinical and clinical data on S1R physiology, pathophysiology, and function. Modulating sigma-1 systems is relevant to current FDA-approved treatments for major depressive disorder and may inform future therapeutic development. Whether sigma-1 modulation uniquely targets difficult-to-treat symptoms like anhedonia remains unknown.
Study at a glance
| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Ketamine |
| Keywords | Sigma-1 receptor Anhedonia Cognition Dextromethorphan Glutamate |
| Citations | 5 |
| Key finding | Sigma-1 receptors regulate neurotransmitter systems and immune responses, and their modulation is relevant to the mechanism of action of the FDA-approved antidepressant dextromethorphan-bupropion. |
Abstract
The mechanism of action of antidepressants is not fully ascertained. In addition to monoamines, disparate other effectors are also implicated in the molecular and cellular effects of chronic stress including neurogenesis, neurodifferentiation, and neuroplasticity. Evidence suggests sigma-1 receptors (S1Rs) as a putative target and possible mediator of antidepressant activity. Data from preclinical and clinical trials was synthesized from inception to August 2024. Results showed that S1Rs regulate neurotransmitter availability and release (e.g. monoamines, glutamate), and influence intracellular Ca2+ levels as well as immune inflammatory responses. The introduction of the N-Methyl-D-aspartic Acid (NMDA) antagonist/S1R agonist dextromethorphan-bupropion in August of 2022 represented the first time the Food and Drug Administration (FDA) permitted language that the hypothesized mechanism of an antidepressant involved activity at S1Rs. We also describe the physiology, pathophysiology, and function of S1Rs. Sigma-1 modulation is relevant to the mechanism of action of agents currently FDA-approved in major depressive disorder (MDD) (e.g. dextromethorphan-bupropion). Modulating sigma-1 systems is fit for purpose as it relates to future therapeutic discoveries and development in depressive and other mental disorders. Whether sigma-1 modulation is uniquely relevant to targeting dimensions of psychopathology that are more difficult to treat (i.e. anhedonia) awaits determination.