September 19, 2026 · 2 min read

SLU-PP-332: an ERR agonist studied as an exercise mimetic

SLU-PP-332 is a synthetic small molecule, not a peptide, that activates estrogen-related receptors. Here is what the mouse studies report.

SLU-PP-332 came out of Saint Louis University, and it is a small molecule, not a peptide. We cover it because it gets lumped in with research peptides, and the published work deserves an accurate description.

Target

It is an agonist of the estrogen-related receptors (ERRs), orphan nuclear receptors that come in alpha, beta and gamma forms. They help regulate mitochondrial function and energy metabolism in tissues like skeletal muscle. The 2023 paper that introduced the compound reports activity at all three, strongest at ERR-alpha.

Cells and mice

In a skeletal muscle cell line, SLU-PP-332 increased mitochondrial function and cellular respiration. In mice it raised the share of type IIa oxidative muscle fibers, improved exercise endurance, and triggered a gene expression program that resembles the response to a bout of aerobic exercise. The authors found that ERR-alpha activation was required for the endurance effect.

A 2024 follow-up used diet-induced obese and ob/ob mice. Treatment increased energy expenditure and fatty acid oxidation, reduced fat mass gain, and improved insulin sensitivity.

From receptor to muscle to metabolism

  1. 1

    ERR agonist

    SLU-PP-332 activates ERR alpha, beta and gamma.

  2. 2

    Muscle cells

    More mitochondrial function and cellular respiration.

  3. 3

    Mice

    More type IIa oxidative fibers and better endurance.

  4. 4

    Obese mice

    More energy expenditure, less fat gain, better insulin sensitivity.

Findings from Billon et al., ACS Chem Biol 2023 and J Pharmacol Exp Ther 2024, all in cells or mice.

Follow-on chemistry

The same group has since reported an orally active analogue, SLU-PP-915, and other labs have published structural optimization of SLU-PP-332 itself. Analytical groups have also characterized its in vitro metabolism, with anti-doping testing in mind.

What is and isn't known

Every primary finding above comes from cell culture or mice. We found no published controlled human trials, so any claim that it works in people goes beyond the evidence.

Where the evidence stands

  1. Cell culture

    Positive findings reported.

  2. Mice

    Positive findings reported.

  3. Controlled human trials

    None found.

Based on the primary papers listed below and our literature search. Not a systematic review.

References

  1. Billon C et al. Synthetic ERR alpha/beta/gamma Agonist Induces an ERR alpha-Dependent Acute Aerobic Exercise Response and Enhances Exercise Capacity. ACS Chem Biol 2023.
  2. Billon C et al. A Synthetic ERR Agonist Alleviates Metabolic Syndrome. J Pharmacol Exp Ther 2024.
  3. Okda HE et al. Chemical optimization of the exercise mimetic SLU-PP-332 enables insight into estrogen-related receptor signaling. Int J Biol Macromol 2026.

Related research notes