SLU-PP-332
Also known as SLU-PP332, SLUPP-332, ERR agonist, exercise mimetic
SLU-PP-332 is a small molecule, not a peptide, that activates the estrogen-related receptors to mimic the metabolic effects of endurance exercise. In mice it increased running endurance and reduced fat gain; no human data exist.
Overview
SLU-PP-332 is not a peptide. It is a synthetic small molecule created in Thomas Burris's lab at Saint Louis University (hence the name) as an agonist of all three estrogen-related receptors, ERR alpha, beta and gamma. Despite the name, these receptors do not bind estrogen. They are transcription factors that switch on the genes for mitochondrial biogenesis and fatty acid oxidation, the same program that endurance training turns on in muscle.
Two mouse papers from 2023 supply the evidence. In the first, treated mice ran about 70 percent longer and farther on a treadmill after a month, with more oxidative muscle fibers. In the second, obese mice given the compound twice daily gained less weight, lost about 12 percent of their fat mass and improved insulin sensitivity without eating less. Energy expenditure went up, which the authors attributed to muscle burning more fatty acids even at rest.
Those studies used intraperitoneal injections at high doses, and the compound has a short half-life and poor reported oral bioavailability. It has been licensed to a biotech company for further development, but no human trial has started. The capsules and powders sold online are typically dosed in the hundreds of micrograms, numbers that do not come from any human pharmacology. It is a genuinely interesting mechanism with a wide gap between the mouse data and what is being marketed.
How it works
Estrogen-related receptors, particularly ERR alpha, sit at the center of the transcriptional program that builds mitochondria and ramps up fatty acid oxidation in skeletal muscle and heart. They normally work with the coactivator PGC-1 alpha, which exercise upregulates. SLU-PP-332 binds the receptors directly and stabilizes their active shape, driving expression of those target genes whether or not the animal has exercised. The result in mice is more oxidative type IIa fibers, higher mitochondrial content and increased whole-body energy expenditure. The obesity effects appear to follow from muscle burning more fat, since food intake did not change. The endurance effect was lost in ERR alpha knockout mice, confirming which receptor matters most.
What the research shows
- rodentMice treated for 4 weeks ran about 70 percent longer before exhaustion, with more oxidative muscle fibers.
- rodentDiet-induced obese mice lost about 12 percent of fat mass and gained less weight over 4 weeks without eating less.
- rodentIncreased whole-body energy expenditure and fatty acid oxidation in treated mice.
- rodentThe endurance effect disappeared in ERR alpha knockout animals, confirming the target.
- in vitroActivated ERR target genes and increased mitochondrial markers in cultured muscle cells.
Evidence labels: rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
No reconstitution needed
SLU-PP-332 is taken orally as capsules or tablets, so there is no vial to mix and nothing to draw into a syringe. The calculator only applies to injectable lyophilized peptides.
Open the calculator for an injectable peptideDosing and protocol
Community protocols run 250 mcg to 1 mg per dose, one to three times daily. Rodent studies used injections around 50 mg per kg, so these numbers are not scaled from any real pharmacology.
4-8 weeks, then reassess. Long-term safety is unknown.
Community use favors dosing before training. There is no evidence-based timing.
Powder or capsules: room temperature, dry, sealed, away from light. Nothing to reconstitute.
Cautions
- ▲Zero human data of any kind. No safety, dosing or absorption information exists for people.
- ▲ERR alpha activity drives metabolism in some cancers and is involved in heart remodeling, so chronic pharmacological activation carries theoretical risk nobody has measured.
- ▲Oral absorption appears poor and the half-life is short, so what capsules actually deliver is anyone's guess.
- ▲Product identity and purity vary between vendors, and the compound is not trivial to synthesize.
- ▲It does not replace exercise. Mice still had to run to show the endurance benefit; the drug changed how their muscle adapted.
Commonly stacked with
Frequently asked
Is SLU-PP-332 a peptide?
No. It is a small synthetic organic molecule that activates nuclear receptors. It is sold by peptide vendors and gets lumped in with peptides online, but chemically and pharmacologically it is closer to a drug like a PPAR agonist than to anything injectable on this site.
Does it replace exercise?
In mice it turned on part of the gene program that exercise activates, and the animals ran longer and burned more fat. It did not build strength, fix cardiovascular fitness or do the dozens of other things training does. Calling it an exercise mimetic is fair for the muscle metabolism piece and misleading for everything else.
How do people dose it?
Typically 250 mcg to 1 mg orally, once to three times daily, often before training. Those figures come from vendor convention, not from any study. Mouse dosing was by injection at levels far higher on a per-kilogram basis.
Is it safe?
Unknown. Mice tolerated a month of treatment with no obvious problems. The receptors it targets are involved in heart and cancer biology, which is a reason to be cautious about long-term use of something with no human safety data.
References
- Synthetic ERR alpha/beta/gamma agonist induces an ERR alpha-dependent acute aerobic exercise response in skeletal muscle. ACS Chemical Biology, 2023
- A synthetic ERR agonist alleviates metabolic syndrome. Journal of Pharmacology and Experimental Therapeutics, 2023