The short version of nuclear receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-26. Anything still debated is marked as such rather than presented as settled.
In the fitness and bodybuilding literature, cardarine is frequently discussed as an endurance agent or fat-loss compound, although such claims are not supported by robust clinical evidence. Online descriptions often mix animal data, user anecdotes, and marketing language. Researchers who study PPARδ agonists distinguish between receptor activation in controlled experiments and unsupervised use of unverified products. The latter introduces unknown purity, dose, and interactions, making reported experiences difficult to interpret scientifically.
GW501516 acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in transcription of genes related to lipid handling and energy use. Activation of PPARδ can shift skeletal muscle toward greater fatty acid oxidation in animal models, which is one reason it drew interest for metabolic disease and exercise research. The exact downstream effects depend on tissue, species, dose, and duration. Human data are sparse, so many proposed benefits remain hypotheses rather than established clinical outcomes.
Laboratory studies have examined GW501516 in cell cultures and rodents for conditions such as dyslipidemia, insulin resistance, and obesity. Some trials in humans were initiated, but development was discontinued after preclinical findings raised concerns about cancer in certain models. Those findings do not prove that the compound causes cancer in people, but they contributed to regulatory caution. Later reviews often describe the evidence as preliminary and insufficient for assessing long-term safety.
Products sold as cardarine have been found to contain incorrect compounds, variable amounts, or no active ingredient at all. Independent testing is required to verify identity and purity. Common analytical approaches include high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance for structural confirmation. These methods can distinguish GW501516 from related PPAR agonists and from unrelated steroids. For regulators and researchers, such verification is central to interpreting both biological results and adverse event reports.
Cardarine is prohibited in competitive sport under the World Anti-Doping Agency code, where it is classified as a metabolic modulator. It is not approved as a prescription medicine in the United States, European Union, or other major markets. Regulatory action has focused on its presence in sports and in products marketed as research chemicals. Because it has no accepted medical indication, supply is often unregulated. This status creates legal and safety uncertainties for anyone who encounters the substance.
Anti-doping laboratories detect GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be used in some programs. Detection depends on factors such as dose, timing, metabolism, and the sensitivity of the assay. Published methods describe limits of detection in the low nanogram per milliliter range for related compounds. Exact detection windows are not fixed for all situations and remain an area of ongoing study.
| Property | Value | Notes |
|---|---|---|
| Solubility | Soluble in dimethyl sulfoxide and some organic solvents; practically insoluble in water | Solvent choice affects laboratory handling |
| Typical storage | -20 °C, desiccated, protected from light | Common condition for research samples |
| Analytical method | Liquid chromatography–tandem mass spectrometry (LC-MS/MS) | Used for identification and quantification in biological or product samples |
| Common synonyms | GW501516, GW-501516, GSK-516, Endurobol | Names found in research and anti-doping literature |
| Regulatory status | Unapproved therapeutic; prohibited in competitive sport | Status can vary by country and context |
Quality assessment for cardarine samples usually combines identity, purity, and impurity testing. Nuclear magnetic resonance spectroscopy and mass spectrometry can confirm molecular structure, while high-performance liquid chromatography estimates purity. Certificates of analysis from testing laboratories may list these results, but they do not establish safety or legality. In the absence of approved manufacturing, products sold online may contain the wrong compound, variable amounts, or unlisted contaminants. Independent verification is therefore central to analytical work and to interpreting any reported biological activity.
Laboratory detection of GW501516 commonly uses liquid chromatography coupled with tandem mass spectrometry. The method can identify the parent compound or its metabolites in urine and blood after sample cleanup. Protein precipitation, solid-phase extraction, or enzymatic hydrolysis may precede analysis, depending on the matrix. Reference standards are required for accurate quantification and confirmation. Because the compound is not approved, testing often occurs in anti-doping, forensic, or research settings rather than routine clinical care. Results are reported with limits of detection and quantification.
Stability of GW501516 depends on form, temperature, light exposure, and moisture. Solid reference material is typically stored frozen or refrigerated in a desiccator and protected from light. Solutions in organic solvents such as dimethyl sulfoxide are often kept frozen in aliquots to reduce freeze-thaw cycling. Aqueous solubility is low, so aqueous stock solutions can be difficult to prepare without cosolvents. Degradation may appear as changes in chromatographic purity or mass spectral signal. Stability studies are needed to establish shelf life for any specific preparation.
Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.
Anti-doping laboratories identify GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the usual matrix, and detection can occur after the parent compound has cleared from blood. The exact detection window depends on dose, formulation, individual metabolism, and assay sensitivity. Because the compound is prohibited at all times, athletes are subject to testing in and out of competition. Analytical methods continue to improve as new metabolites and designer analogs are characterized.
GW501516 acts as a ligand for PPAR delta, a nuclear receptor that regulates transcription of genes involved in fatty acid oxidation and energy use. Activation of this receptor in skeletal muscle shifts metabolism toward fat burning in animal models. The compound does not burn fat directly; it changes gene expression over hours to days. Researchers study it to understand metabolic flexibility and exercise adaptation. Effects observed in rodents are not automatically expected in humans.
=== Antibody-based method === Antibodies are known for their high affinity and selectivity, making them a good way to detect AMPylated proteins. Recently, ɑ- AMP antibodies were developed to directly detect and isolate AMPylated proteins (especially AMPylated tyrosine and AMPylated threonine) from cells and cell lysates. AMPylation is a post-translational modification that can be found on many protein sequences. Thus, instead of using antibodies that detect a specific AMPylated peptide sequence, raising AMP antibodies directly targeted to specific amino acids are considered superior.
A mineralocorticoid receptor antagonist (MRA or MCRA) or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is often used as adjunctive therapy, in combination with other drugs, for the management of chronic heart failure. Spironolactone, the first member of the class, is also used in the management of hyperaldosteronism (including Conn's syndrome) and female hirsutism (due to additional antiandrogen actions). Most antimineralocorticoids, including spironolactone, are steroidal spirolactones. Finerenone is a nonsteroidal antimineralocorticoid.
== Early life and education == Valerie Horsley was raised by a single mother, who was working toward her doctorate in industrial engineering throughout her early childhood. Horsley was often placed in the care of graduate students, who served as her babysitters. She initially considered a career in medicine working as a physician, but opted to pursue a career in research instead. In 1998, Horsley achieved a Bachelor of Science in biology at Furman University, and later her doctorate from Emory University in 2003.
== Cold CNO cycles == Under typical conditions found in stars, catalytic hydrogen burning by the CNO cycles is limited by proton captures. Specifically, the timescale for beta decay of the radioactive nuclei produced is faster than the timescale for fusion. Because of the long timescales involved, the cold CNO cycles convert hydrogen to helium slowly, allowing them to power stars in quiescent equilibrium for many years.
== Function == HLA-G is a major immune checkpoint, meaning it downregulates the immune system's response. Soluble HLA-G can be found in the saliva, ascitic fluid, plasma, thymus, seminal plasma, cerebrospinal fluid, and in first and second term placentas. Membrane-bound HLA-G is predominantly found on trophoblast cells in the placenta, but it is also found in the thymus, cornea, erythroblasts, and mesenchymal stem cells. It can be upregulated in cancers. Peptides are connected to HLA-G by the peptide loading complex in the endoplasmic reticulum.
Sources: en.wikipedia.org
Bovine somatotropin or bovine somatotrophin (abbreviated bST and BST), or bovine growth hormone (BGH), is a peptide hormone produced by cows' pituitary glands. Like other hormones, it is produced in small quantities and is used in regulating metabolic processes. Recombinant bovine somatotropin (usually "rBST") is a synthetic version of the bovine growth hormone given to dairy cattle by injection to increase milk production. BST increases milk production by around 10 percent. Controversy over its safety for cows has led to rBST being banned in several countries, including the European Union since 1990, and Canada, Japan, Pakistan, Australia, New Zealand, and Argentina, as it has been found to increase health risks in cows. The Codex Alimentarius has not approved it as safe. The FDA approved it in 1993 and gave guidance to manufacturers that marking a product as "bST-free" or "rbST free" is misleading and a less misleading text would be "No significant difference has been shown between milk derived from rbST-treated and non-rbST-treated cows".
=== Primary sources === Cross, J. P., and Buddhiman Gurung, eds. Gurkhas at War in Their Own Words: The Gurkha Experience 1939 to the Present (London: Greenhill, 2002), Masters, John (1956). Bugles and a Tiger: Viking. (autobiographical account of his service as a junior British officer in a Gurkha regiment in the years leading up to World War II) Omissi, David E. ed. Indian Voices of the Great War: Soldiers' Letters, 1914–18 (1999) Francis J Short. Stories from the British Indian Army (2015)
Cy1: Curly; the wings curve away from the body, flight may be somewhat impaired e1: Ebony; black body and wings (heterozygotes are also visibly darker than wild type) Sb1: Stubble; bristles are shorter and thicker than wild type w1: White; eyes lack pigmentation and appear white bw: Brown; eye color determined by various pigments combined. y1: Yellow; body pigmentation and wings appear yellow, the fly analog of albinism
In 2019, Dream Market was the most popular market by far, with over 120,000 current trade listings, followed at one time by Wall Street Market with under 10,000 listings. Dream Market was shut down in 2019, and Wall Street Market was seized by law enforcement in May 2019 as part of an Internal Law Enforcement Operation Dark Huntor. That same operation also shut down the dark markets DeepSea, Berlusconi, White House, and Dark Market. The May 2019 seizure of news and links site DeepDotWeb for conspiring with the markets created a temporary disruption around market navigation. In 2021, authorities took down the dark web marketplace DarkMarket, along with arresting the Australian man who was believed to be the operator of the website. The 20 servers that hosted the website were seized. In August 2021, AlphaBay was relaunched after the return of one of the original security administrators DeSnake. In June 2025, Europol took down the Archetyp Market with an estimated 3200 registered vendors and 600,000 customers worldwide.
== I == IgA - IgE receptor - IGF type 1 receptor - IGF type 2 receptor - IgG - IgM - immediate-early protein - immune cell - immune system - immunoglobulin - immunoglobulin joining region - immunoglobulin variable region - immunologic receptor - immunology - In vivo - infrared spectroscopy - inhibin - inhibitor - inhibitory gi G-protein - Inorganic chemistry - insect protein - Insulin - insulin receptor - insulin-like growth factor I - Integral membrane protein - intein - intercellular adhesion molecule-1 - interferon receptor - interferon type I - interferon type II - interferon-alpha - interferon-beta - interleukin receptor - interleukin-1 receptor - interleukin-2 receptor - interleukin-3 - interleukin-3 receptor - intermediate filament - intermediate filament protein - intermembrane space - Intermolecular force - International Union of Pure and Applied Chemistry (IUPAC) - interphase - intracisternal A-particle gene - Intramolecular force - intron - Inverse agonist - invertebrate peptide receptor - invertebrate photoreceptor - Ion channel - ion channel gating - Ionic bond - ionization potential - iron–sulfur protein - isoenzyme - isoleucine - Isomer - Isothermal titration calorimeter - Isotopic tracer
Sources: en.wikipedia.org
It binds and activates PPARδ, a nuclear receptor that influences gene expression related to fatty acid metabolism and energy balance. This mechanism has been studied mainly in animals and cell models, not established as a safe human therapy.
No. It is not an anabolic-androgenic steroid; it is a synthetic PPARδ agonist. Because it is banned in sport, it is sometimes grouped with doping agents even though its chemical class differs from steroids.
Human data are limited and development was discontinued, so major effects and long-term risks are not well characterized. Some early studies examined metabolic markers, but they do not provide a basis for unsupervised use.
Legal status varies by country, but cardarine is not approved as a medicine in major jurisdictions. It is often sold as a research chemical, a category that may not be lawful for human use. Buyers should check local laws and product labels carefully.