Sigma-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.
Lysergic acid diethylamide and 3,4-methylenedioxymethamphetamine activate the 5-hydroxytryptamine 2B receptor, a pathway known to cause drug-induced valvular heart disease. This systematic review of 17 studies found no research on psilocybin, dimethyltryptamine, or mescaline. Both lysergic acid diethylamide and 3,4-methylenedioxymethamphetamine show high or moderate affinity for this receptor and promote signaling linked to fibrotic changes in heart valve tissue. In vivo studies confirm serotonin-induced valvulopathy, and chronic 3,4-methylenedioxymethamphetamine use has been associated with valve abnormalities in humans. No clinical cases of lysergic acid diethylamide-induced valvulopathy have been reported, but preclinical data suggest potential for fibrotic signaling under sustained exposure. Preliminary evidence supports the need for cardiac safety monitoring in psychedelic research.