DMT and the sigma-1 receptor: what the 2009 discovery does and doesn’t show

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Sigma-1 is the receptor that turns up whenever people argue DMT is more than a psychedelic: a natural protector of brain cells, perhaps, or the key to why the body makes it at all. This article separates what was actually shown, in which species and at what concentration, from what has been proposed. For the receptor most researchers think drives the psychedelic effects, see DMT and the 5-HT2A receptor; for the molecule itself, what is DMT.

What is the sigma-1 receptor?

Despite the name, sigma-1 is unlike most receptors. It was originally mischaracterized as an opioid receptor; it binds a vast number of synthetic compounds but not the body’s opioid peptides, and in 2009 it was still considered an “orphan” receptor with no known natural partner. It is widely distributed in the central nervous system and the rest of the body (Fontanilla et al., 2009). Evidence: established.

Its main home is inside the cell. A 2007 study found sigma-1 sits on the endoplasmic reticulum, the cell’s protein-folding network, at the contact points with mitochondria, where it acts as a calcium-sensitive “chaperone” that helps steady calcium signalling into the mitochondria. In cells, more sigma-1 counteracted stress responses in the endoplasmic reticulum, and less sigma-1 increased cell death (Hayashi and Su, 2007). That is why it is often linked to cell survival and neuroprotection. Evidence: established as cell biology.

What did the 2009 DMT sigma-1 receptor study find?

A team at the University of Wisconsin noticed that DMT carries a chemical feature common to sigma-1 binders. They found that tryptamine itself bound sigma-1 poorly, but adding methyl groups to the nitrogen made binding tighter, and DMT bound sigma-1 receptors. DMT inhibited voltage-gated sodium channels in heart muscle cells and in cells engineered to carry sigma-1, and it made wild-type mice hypermobile but had no such effect in mice lacking sigma-1. They concluded DMT is an endogenous agonist for the sigma-1 receptor (Fontanilla et al., 2009). Evidence: established as a lab and mouse finding.

Why heart cells? Sigma-1 activation is known to inhibit several ion channels, and sodium channels in heart muscle were a convenient, measurable target. The team confirmed sigma-1 dependence by comparing heart cells from normal mice with cells from mice bred without sigma-1 (Fontanilla et al., 2009). A review notes that sigma-1 can move toward the cell surface to interact with ion channels when it is stimulated with higher concentrations of activators (Carbonaro and Gatch, 2016), which ties back to the concentration question below. Evidence: established as a cell finding.

Note what the study measured. Hypermobility in mice is a behaviour, not a psychedelic effect, and the sodium-channel work was in isolated cells. The same paper says there were no conclusive measurements of how much DMT the body makes, because it is broken down so fast (Fontanilla et al., 2009). A commentary in the same year proposed a hypothetical signalling scheme by which sigma-1 might partly mediate DMT’s effects, framed as a possibility (Su et al., 2009). Evidence: preliminary.

Is there ever enough DMT to activate sigma-1?

This is the central weakness. A review notes that DMT binds sigma-1 only at “what should be considered as a high concentration”, in the micromolar range, against the nanomolar range for 5-HT2A, a gap of roughly 190-fold, and that both hallucinogens and non-hallucinogens bind sigma-1, which complicates treating it as DMT’s main site of action (Barker, 2018). A 2009 drug-target study put DMT’s potency at 5-HT2A about 100-fold better than at sigma-1, and concluded 5-HT2A is the primary target for its hallucinogenic effects (Keiser et al., 2009). Evidence: established.

Another review calls this “the main problem” with the theory: DMT needs micromolar concentrations, whereas selective sigma-1 drugs work in the nanomolar range (Carbonaro and Gatch, 2016). Compare the levels actually measured. Modelling of human lab data estimated the blood concentration at which DMT produced half its maximum intensity, and that figure is roughly 150 times lower than the sigma-1 activity level (Eckernäs et al., 2022; Barker, 2018). In living rats, average DMT in the cortex was 0.56 nanomolar with a pineal gland and 1.02 without one, and even the highest values recorded after experimental cardiac arrest were thousands of times below that level (Dean et al., 2019). The rat study is explained in full in the DMT rat brain study, explained. Evidence: established for the gap; whether local concentrations could ever close it is unresolved.

Could local levels be much higher?

Supporters of the sigma-1 idea argue they might be. In mouse motor neurons, the enzyme long credited with making DMT, INMT, sits right beside sigma-1 at certain synapses, and the authors suggest DMT is made locally to activate sigma-1 there (Mavlyutov et al., 2012). A review also describes evidence that DMT can be taken up and stored in vesicles inside cells, and says high vesicle concentrations would be needed for sigma-1 activation (Carbonaro and Gatch, 2016). Both are proposals: no one has measured DMT at sigma-1-activating levels inside living neurons. Gene-knockout studies have since questioned whether INMT makes DMT in rodents at all; see INMT: the enzyme said to make DMT. Evidence: unresolved.

Does sigma-1 explain the DMT experience?

There is no human evidence that it does. One review concludes that, at best, sigma-1 receptors may partially mediate DMT’s subjective effects (Carbonaro and Gatch, 2016). We found no published study that blocked sigma-1 before giving people DMT, and the animal and receptor evidence points to 5-HT2A as the main driver (Keiser et al., 2009). Evidence: unresolved.

Does DMT protect cells through sigma-1?

Most of what is said online about DMT “protecting the brain” traces back to a small set of lab studies, several of them sharing authors. They are listed here with what each model can and cannot show. None involved people taking DMT.

In human immune cells in a dish (monocyte-derived dendritic cells), DMT and 5-MeO-DMT reduced the release of several inflammatory signals and increased an anti-inflammatory one when the cells were provoked, and gene silencing confirmed a sigma-1 role (Szabo et al., 2014). In 2016, the same group reported that DMT robustly increased the survival of human stem-cell-derived cortical neurons and immune cells kept in severe oxygen shortage in culture, through sigma-1 (Szabo et al., 2016). Evidence: preliminary, from cells.

In anaesthetised rats with experimentally induced global brain ischaemia (loss of blood flow), DMT reduced spreading depolarizations, waves of electrical shutdown that damage tissue, and reduced the number of dying cells; a sigma-1 blocker counteracted the effect (Szabó et al., 2021). In a rat stroke model, DMT had previously reduced the volume of damaged tissue, and a 2025 study added that it reduced brain swelling, helped restore the blood-brain barrier, and reduced inflammatory activity in brain immune cells via sigma-1 (László et al., 2025). Evidence: preliminary, from rats.

The researchers behind this work have framed DMT as an agent of adaptive, protective mechanisms rather than mainly a hallucinogen (Frecska et al., 2013). That is an interpretation, not a finding. Lab concentrations, animal models and anaesthesia all differ from human physiology. Evidence: unresolved.

It also matters that DMT is not unique here. In the 2014 immune-cell study, 5-MeO-DMT, a related but different psychedelic, had similar sigma-1-dependent effects, and a synthetic, high-affinity sigma-1 drug was used as a comparison (Szabo et al., 2014). The rat ischaemia study likewise compared DMT with a selective synthetic sigma-1 activator, and both reduced spreading depolarizations (Szabó et al., 2021). What these studies show, then, is mainly that activating sigma-1 can protect cells in these models, and that DMT is one of several molecules that can do it at lab concentrations. For how 5-MeO-DMT differs from DMT, see 5-MeO-DMT vs DMT. Evidence: preliminary.

What has been tested in people?

Only safety groundwork, and none of it on sigma-1. A randomized, double-blind, placebo-controlled study in the Netherlands gave 29 healthy volunteers a six-hour intravenous DMT infusion (amounts not reproduced here) as a basis for future studies in stroke patients. No serious adverse events occurred, and effects were mild (van der Heijden et al., 2025). That study measured safety, blood levels and mild drug effects in healthy people. It did not test whether DMT protects the brain, and it did not measure sigma-1. Whether any of the rat findings apply to people is unknown; our DMT therapy research overview tracks the clinical studies, and is DMT neuroprotective? covers the claim in full. Evidence: established that no human sigma-1 or efficacy data exist in the sources we read.

What is still unknown?

• Whether DMT ever reaches sigma-1-activating concentrations anywhere in a living body, including inside cells (unresolved).
• Whether sigma-1 contributes anything to the DMT experience in people; no human blocking study exists that we found (unresolved).
• Whether the cell and rat protective findings replicate in independent labs and apply to humans (unresolved).
• Whether sigma-1 is a natural role for DMT made in the body, as proposed in 2009 (unresolved).

The fair summary: DMT does bind and activate sigma-1, in cells and mice, but only at concentrations far above those seen in human studies or living rat brains. The protective findings are real lab results in cells and rats, not evidence of anything in people. Evidence: established for binding; preliminary for protection; unresolved for any role in people. For the wider receptor picture, see psilocybin, LSD and DMT: how they differ.

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