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.
Reviewed by the amino101 editorial team. , first published .
Quick start
What people commonly do. Not a prescription.- Typical dose
- 250 mcg
- How often
- once to three times daily
- Where
- Subcutaneous, belly or thigh, rotate sites. Also sold as capsules.
- Timing
- before training in community use; there is no evidence-based timing
- Effects timeline
- no human data; mouse endurance and fat changes appeared over 4 weeks of daily injections
- Storage
- fridge 2 to 8 C once mixed, use within 4 weeks
- Cycle length
- 4 to 8 weeks
- Break between
- 4 weeks, then reassess whether anything measurable changed
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.
Where the research stands
Endurance and exercise capacityEmerging
- Running endurance. Mouse study, about 70 percent longer time to exhaustion after 4 weeks, with more oxidative muscle fibers.
- Muscle mitochondrial adaptation. Rodent and cell work showing ERR target genes and mitochondrial markers switched on in muscle.
Fat lossEmerging
- Diet-induced obesity. Mouse study, about 12 percent fat mass lost over 4 weeks with higher energy expenditure and no reduction in food intake.
Heart failureWeak or mixed
- Cardiac energy metabolism. Rodent heart failure models from the same lab showed improved cardiac function with ERR activation; no human data.
- 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.
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.
Levels over time
Modeled from the half-life. Illustrative, not measured.A half-life of 1 h against dosing every 24 h means each dose has cleared before the next. Nothing stacks; you start from zero every time, and the tissue effect is what carries over.
A half-life around an hour, combined with poor oral absorption in rodents, is why community protocols split dosing into one to three times daily and why an oral capsule may deliver very little of the compound.
SLU-PP-332 dosage and protocols
Community protocols run 4 to 8 weeks then stop, partly because long-term ERR activation carries theoretical heart and cancer concerns nobody has measured. No loading or tapering; people start at the low end and add doses if nothing is felt.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Conservative start | 250 mcg | once daily | Subcutaneous or oral |
| Common community protocol | 500 mcg | once or twice daily | Subcutaneous or oral |
| Upper end reported | 1 mg | one to three times daily | Subcutaneous or oral |
Most community users take it 30 to 60 minutes before training on the theory that it primes the same pathways exercise does. Nothing supports that timing; the mouse studies dosed once daily regardless of activity. Avoid late evening doses if it disturbs sleep.
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. Sold both as lyophilized vials for subcutaneous injection and as oral capsules; injectable use avoids the poor oral absorption seen in rodents.
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 5 units |
| 10 mg | 2 mL | 5 mg/mL | 5 units |
How to reconstitute SLU-PP-332
- 1
Wash your hands and wipe the work surface. Swab both vial stoppers with alcohol and let them dry.
- 2
Pick the water volume with the calculator above and write it on the vial. The concentration means nothing without it.
- 3
Draw the bacteriostatic water into a mixing syringe.
- 4
Insert at an angle and let the water run down the inside wall. Never squirt it straight onto the powder.
- 5
Swirl gently or leave it to dissolve. Do not shake.
- 6
Label with the date and water volume. Store in the fridge at 2 to 8 C and use within about 4 weeks.
- 7
Unmixed vials keep for months in the fridge and longer in the freezer, sealed and out of light.
- Full walkthrough with syringe reading and site rotation: reconstitution guide.
- ✓White, fluffy cake
Lyophilized powder should look like a small white puck or fluffy cake at the bottom of the vial. That is a proper freeze-dry.
- ✓Clear after mixing
Once dissolved the solution should be water-clear with nothing floating in it.
- !Slight clumping
Small clumps that dissolve with gentle swirling are fine. Shipping compacts powder.
- ✕Collapsed or melted
Powder stuck to the sides, glassy, or shrunken means it got hot in transit. Contact the vendor.
- ✕Cloudy or particles
Persistent cloudiness or visible particles after mixing means degraded or contaminated product. Do not use it.
- Week 1 to 2
Usually nothing. Some people report a mild stimulant-like feeling or trouble sleeping with late doses, which may or may not be the compound.
- Week 2 to 8
If anything, a subjective sense of better endurance in training; body composition changes are not reliably reported and there is no human data to set expectations.
Interactions and stacking
MOTS-ccompatible
Both are marketed as exercise mimetics and get stacked in community protocols; overlapping metabolic pathways, no combined data.
5-Amino-1MQcompatible
Two untested fat-loss small molecules with different targets; stacking them makes any side effect impossible to attribute.
NAD+compatible
ERR activation drives mitochondrial biogenesis, which NAD+ feeds; a logical pairing with no data.
Semaglutidecompatible
Different mechanism, appetite versus energy expenditure; no conflict expected and no combined data.
Stimulants and pre-workout productscaution
Both raise energy expenditure and heart rate; anecdotal reports of palpitations are more common when they are combined.
Heart medicationscaution
ERR alpha is involved in cardiac remodeling, and anyone on drugs for heart rhythm or heart failure has no data to lean on.
Safety
- ▲No human safety data exist, so this list is anecdotal
- ▲Faster resting heart rate or palpitations
- ▲Trouble sleeping with evening doses
- ▲Stomach upset
- ▲Headache
- ▲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.
- ■Palpitations, chest discomfort or a resting heart rate that stays elevated
- ■Unusual fatigue or shortness of breath during training rather than improvement
- ■No measurable change after 8 weeks; there is no reason to keep taking an untested compound
- ■You compete in tested sport; unapproved substances are prohibited under the WADA catch-all rule
Community poll
Self-reported by visitors. Not clinical evidence.SLU-PP-332: 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