SLU-PP-332: The ERR Engine
SLU-PP-332 is a synthetic pan-estrogen-related receptor agonist that activates an aerobic exercise-like transcriptional program, increases skeletal-muscle mitochondrial respiration, improves endurance in mice, and shows organ-protective signals in preclinical heart, kidney, liver, and metabolic-disease models.
At a glance
What the evidence says
SLU-PP-332 is a synthetic pan-estrogen-related receptor agonist that activates an aerobic exercise-like transcriptional program, increases skeletal-muscle mitochondrial respiration, improves endurance in mice, and shows organ-protective signals in preclinical heart, kidney, liver, and metabolic-disease models.
In the full-text preprint, SLU-PP-332 increased maximum mitochondrial respiration in C2C12 myocytes, increased mitochondrial biogenesis markers, increased mitochondrial DNA, and increased muscle complex I, complex V, cytochrome c, SDH staining, and mitochondrial content in vivo (bioRxiv full text).
In chow-fed, diet-induced obese, and ob/ob mice, SLU-PP-332 lowered respiratory exchange ratio, increased fatty-acid oxidation, elevated energy expenditure, and did not increase locomotor activity or food intake, which supports an exercise-mimetic rather than stimulant-like profile in mice (JPET).
Mitochondria
Oxidative capacity rises in skeletal muscle and other high-energy tissues in preclinical models.
Metabolism
Fuel use shifts toward fat oxidation and lower respiratory exchange ratio without a stimulant-like increase in movement.
Translation
Human efficacy is unproven; the literature remains preclinical and development-stage.
The big idea
SLU-PP-332 is best understood as a small-molecule ERR agonist that makes sedentary or metabolically stressed mouse tissue look more endurance-trained. Across the published preclinical data, the signal is not simple stimulation; it is a coordinated shift toward oxidative metabolism, mitochondrial support, and higher fatty-acid use.
That is why the strongest effects cluster in skeletal-muscle endurance, diet-induced obesity, heart failure, aging kidney biology, and other high-energy tissues where ERR-governed metabolic programs matter most.
Best preclinical studies
| Study area | What it found | Why it matters |
|---|---|---|
| Exercise endurance | SLU-PP-332 increased treadmill running time and distance in mice and depended on ERRα-linked programming in muscle. | Strongest direct support for exercise-mimetic positioning. |
| Metabolic syndrome | In obese and chow-fed mice, it lowered respiratory exchange ratio, increased fatty-acid oxidation, reduced fat gain, and improved glucose handling without reducing food intake. | Suggests a true metabolic remodeling effect rather than appetite suppression. |
| Heart failure | ERR agonist treatment improved ejection fraction, fibrosis, survival, and oxidative metabolism in pressure-overload heart failure models. | Supports organ protection through preserved mitochondrial energy handling. |
| Aging kidney | Older mice showed improved albuminuria, better podocyte markers, higher mitochondrial biogenesis signals, and lower inflammatory signaling. | Extends the compound beyond muscle into broader organ-resilience biology. |
Performance signal
In the full-text preprint, SLU-PP-332 increased maximum mitochondrial respiration in C2C12 myocytes, increased mitochondrial biogenesis markers, increased mitochondrial DNA, and increased muscle complex I, complex V, cytochrome c, SDH staining, and mitochondrial content in vivo (bioRxiv full text).
In chow-fed, diet-induced obese, and ob/ob mice, SLU-PP-332 lowered respiratory exchange ratio, increased fatty-acid oxidation, elevated energy expenditure, and did not increase locomotor activity or food intake, which supports an exercise-mimetic rather than stimulant-like profile in mice (JPET).
The practical interpretation is that SLU-PP-332 reproduces multiple molecular and physiological features associated with aerobic training, especially improved oxidative muscle programming and greater use of fat as fuel.
Organ health
SLU-PP-332 and SLU-PP-915 improved ejection fraction, fibrosis, and survival in pressure-overload heart failure while increasing mitochondrial oxidative capacity and fatty-acid use, and SLU-PP-332 reversed aging-kidney albuminuria, podocyte loss, mitochondrial dysfunction, and inflammatory signaling in 21-month-old mice (Circulation, The American Journal of Pathology).
The organ-health case is strongest when SLU-PP-332 is framed as a metabolic-resilience signal across muscle, heart, kidney, liver, and adipose tissue rather than as a narrow body-composition drug.
Mechanism map
| Mechanism | What SLU-PP-332 appears to do | Why it matters |
|---|---|---|
| ERR activation | Activates ERRα, ERRβ, and ERRγ, with strongest emphasis on ERRα in the skeletal-muscle endurance story. | ERRs govern oxidative metabolism, mitochondrial programming, and exercise-linked transcriptional responses. |
| Mitochondrial respiration | Raises cellular respiration, oxidative markers, mitochondrial content, and biogenesis-linked signals in preclinical tissues. | Supports higher aerobic capacity and better energy handling under stress. |
| Fuel selection | Lowers respiratory exchange ratio and increases fatty-acid oxidation without higher locomotor activity. | Fits an exercise-mimetic metabolic shift rather than a stimulant pattern. |
| Inflammation control | In aging kidney and stressed tissues, lowers inflammatory signaling linked to mitochondrial dysfunction. | Connects improved mitochondrial function with lower tissue injury and inflammatory drift. |
What the data does not prove
The University of Florida research summary described SLU-PP-332 as still requiring structural refinement, additional animal side-effect testing, and later human trials, and a 2026 doping-control paper described SLU-PP-332 as an exercise mimetic with metabolites being characterized for sports-drug testing purposes (University of Florida News, Drug Testing and Analysis).
The current evidence does not prove human performance enhancement, human fat loss, or safe clinical use. Most of the data come from mouse or other preclinical models using injection-heavy dosing regimens that cannot be directly translated into human use.
It is also not a peptide in the primary literature; it is a synthetic small-molecule ERR agonist. That distinction matters for both mechanism and expectations.
Bottom line
SLU-PP-332 is best understood as a preclinical chemical tool for turning on ERR-governed oxidative metabolism, not as a proven human performance drug or approved therapy.
Its most interesting signal is that it can make sedentary or metabolically stressed mouse tissue behave more like endurance-trained tissue across muscle, metabolism, and select organ systems.
