If you have been reading about Nuclear receptor and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-04-25. Numbers and descriptions here follow the published literature rather than marketing material.
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.
A persistent misconception is that cardarine is a fat-burning drug or a safe alternative to anabolic steroids. No approved therapeutic product exists, and human safety data are limited. The tumor findings in rodents remain a central concern in scientific reviews. Products sold online may contain inaccurate labels, impurities, or different compounds entirely, which complicates any assessment of effects. Independent testing of such products has reported frequent mislabeling. For these reasons, discussions in the literature emphasize risks and unknowns rather than benefits.
Cardarine is not approved for human therapeutic use in any major jurisdiction. It appears on the World Anti-Doping Agency Prohibited List as a PPARδ agonist within the hormone and metabolic modulators category. Sports organizations test for it because it has been detected in athlete samples and seized products. Regulatory actions against marketed research chemical versions have occurred in several countries, though enforcement varies. Availability through unregulated channels complicates oversight.
Analytical laboratories typically identify cardarine and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is a common matrix in anti-doping testing, while blood and tissue may be used in research settings. Detection windows depend on the assay, the sample matrix, and the compound's metabolism. Because cardarine is extensively metabolized, laboratories often target specific metabolites to improve sensitivity and confirmation. Reference standards are required for reliable quantification. Method validation includes checks for selectivity, linearity, and carryover.
| Property | Value | Notes |
|---|---|---|
| Molecular target | PPAR delta (NR1C2) | Ligand-activated nuclear receptor. |
| Primary tissues studied | Skeletal muscle, liver, adipose | Effects on fatty acid oxidation and energy use. |
| Typical detection matrix | Urine | Used in anti-doping analysis. |
| Common analytical method | LC-MS/MS | Detects parent compound and metabolites. |
| Sport regulatory class | Prohibited at all times | Listed as a metabolic modulator by WADA. |
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.
A common misconception is that cardarine has been proven safe for human use. In reality, human clinical data are limited, and long-term animal studies have raised concerns about cancer. Another misconception is that it is a supplement or vitamin-like compound. It is a synthetic research chemical with no approved medical indication. Scientific discussion often focuses on its mechanism and detection rather than therapeutic use. Regulatory and anti-doping literature treats it primarily as a prohibited substance.
Cardarine is explicitly prohibited by the World Anti-Doping Agency under the class of PPARδ agonists. Its presence in urine or blood samples can be detected using mass spectrometry-based methods, often liquid chromatography-tandem mass spectrometry. Athletes who test positive may face sanctions, including bans from competition. The compound is also regulated as a prescription-only or unapproved drug in many countries. Enforcement varies by jurisdiction, and some regions treat it as a controlled substance. Online sales may occur despite these restrictions, creating quality and legal risks.
PPARδ is a nuclear receptor that regulates gene expression related to fatty acid oxidation, glucose homeostasis, and mitochondrial function. GW501516 binds to this receptor with high affinity and activates downstream signaling in skeletal muscle and other tissues. Animal studies reported increased endurance and altered fuel preference, but human data remain limited and inconsistent. The precise relationship between receptor activation and observed physiological changes is still an area of active investigation. Researchers have also examined whether the compound affects inflammation or cell proliferation. No approved therapeutic indication exists for cardarine.
In laboratory settings, cardarine is studied as a tool compound for probing PPARδ biology. Published experiments often use cell cultures, rodent models, or isolated tissues. Some investigations focus on metabolic effects, while others assess potential risks such as carcinogenicity observed in long-term animal studies. Because human trials are sparse, most knowledge comes from preclinical work and adverse event reports. Scientific literature frequently notes the gap between animal findings and human outcomes. The compound is not a dietary supplement and is not intended for human consumption.
==== Marginality: Abortion and Chicano Rights ==== At a time where both the Chicano Movement and the Abortion rights movement were well underway, many Mexican-American women were pushed to the margins of both historical developments. The Chicana women interviewed in No Más Bebés (2015) briefly touched on experiences of neglect from white feminist developments; while Antonia Hernandez and ten immigrant mothers were fighting for the right to bear children, many white, women activists were advocating for the legal right to immediate sterilization. In other words, white women wanted to establish on-demand sterilizations while Chicana women were advocating against the harmful policy. The absence of a waiting period for (postpartum) sterilizations put non-white women like Maria Hurtado, Consuelo Hermosillo, and Maria Figueroa in direct danger of forceful sterilization. In essence, the racialization of Latina's bodies had profound effects on their inclusion in the Women's Rights Movement of the 1960s and 1970s. This plays a significant role in how the Abortion Rights Movement is remembered in particular; though it is often characterized by inclusive activism, the lived experiences of Mexican-American women prove otherwise. Several women from the No Más Bebés documentary also expressed the disregard of Mexican-American men within the Chicano Movement. Though none of the women involved in the Madrigal v. Quilligan case directly participated in the Chicano Movement kickstarted by Cesar Chavez's United Farm Workers Movement, their lives were uprooted by postpartum sterilizations.
Rotating cell‑based ligand binding assay using radioactivity or fluorescence, is a recent method that measures molecular interactions in living cells in real-time. This method allows the characterization of the binding mechanism, as well as Kd, kon and koff. This principle is being applied in several studies, mainly with protein ligands and living mammalian cells. An alternative technology to measure protein interactions directly on cells is Real-Time Interaction Cytometry (RT-IC). In this technology, the living or fixed cells are physically retained on the surface of biosensor chips using biocompatible and flow-permeable polymer traps. Binding and unbinding of automatically injected labeled analytes is measured by time-resolved fluorescence detection. Single colour reflectometry (SCORE) is a label-free technology for measuring all kinds of biomolecular interactions in real-time. Similar to BLI, it exploits interference effects at thin layers. However, it does not need a spectral resolution but rather uses monochromatic light. Thus, it is possible to analyse not only a single interaction but high-density arrays with up to 10,000 interactions per cm2. switchSENSE is a technology based on DNA nanolevers on a chip surface. A fluorescent dye as well as the unlabeled ligand are attached to this nanolever. Upon binding of an analyte to the ligand, the real-time kinetic rates (kon, koff) can be measured as changes in fluorescence intensity and the Kd can be derived.
== Analytical techniques used for characterizing lipids == There are various analytical instruments and techniques used to characterized and monitor the different properties of lipids; X-ray diffraction, differential scanning calorimetry (DSC), nuclear magnetic resonance which include 2HNMR and 31PNMR, thin layer chromatography (TLC), fluorescence recovery after photobleaching (FRAP), nearest-neighbor recognition (NNR), and atomic molecular dynamics simulations (AMDS).
=== Peptide modifications === Radical SAM enzymes that can catalyze sulfur-to-alpha carbon thioether cross-linked peptides (sactipeptides) generate a class of peptide with antibacterial properties. These peptides belong to the emerging class of ribosomally synthesized and post-translationally modified peptides (RiPPs). Another subset of peptide-modifying radical SAM enzymes is SPASM/Twitch domain-carrying enzymes. SPASM/Twitch enzymes carry a functionalized C-terminal extension for the binding of two [4Fe-4S] clusters, especially in post-translational modifications of peptides. The following examples are representative enzymes that can catalyze peptide modifications to generate specific natural products or cofactors.
Radial chromatography is a form of chromatography, a preparatory technique for separating chemical mixtures. It can also be referred to as centrifugal thin-layer chromatography. It is a common technique for isolating compounds and can be compared to column chromatography as a similar process. A common device used for this technique is a Chromatotron. Here the solvent travels from the center of the circular chromatography silica layered on a plate towards the periphery. The entire system is kept covered in order to prevent evaporation of solvent while developing a chromatogram. The wick at the center of system drips solvent into the system which the provides the mobile phase and moves the sample radially to form the sample spots of different compounds as concentric rings. Continuous annular chromatography uses a stationary phase which is filled into an annular gap. The eluent is continuously fed across the whole bed interface also the feed is continuously fed at the top of the stationary however only at a certain point and not a cross the whole bed. The stationary phase is then rotated with a certain rotation speed. The rotation speed, eluent and feed flow rates have to be defined precisely such that the collector vessels only collect the correct substance. The retention times are transformed into the respective retention angles.
Sources: en.wikipedia.org
Prime Minister Pedro Sánchez also said that they would not recognize a US intervention that violates international law after President Trump announced that the US would run Venezuela. Sweden: Prime Minister Ulf Kristersson stated that "Venezuela has been one of the world's most ruthless socialist dictatorships," adding that "the Venezuelan people have been freed from Maduro's dictatorship," whilst reiterating that "all states have a responsibility to respect and act in accordance with international law". Foreign Minister Maria Malmer Stenergard stated that "dictator Nicolás Maduro lacked democratic legitimacy. The Swedish government sheds no tears over the fact that he has lost power," but that "Venezuela's future must be decided by the Venezuelan people. Respecting the will of the Venezuelan people and achieving a negotiated, democratic, and peaceful solution is the only way for Venezuela to restore democracy and resolve the ongoing crisis." Switzerland: The Federal Department of Foreign Affairs stated that "Switzerland has called for de-escalation, restraint and respect for international law." The Swiss government later ordered to freeze potential assests by Maduro in the country. Turkey: Turkey said it was monitoring the situation in Venezuela, and urged restraint and called on all parties maintain order for the sake of regional and international security and safety. Ukraine: Foreign Minister Andrii Sybiha stated that "Ukraine has consistently defended the right of nations to live freely, free of dictatorship, oppression, and human rights violations.
In 2008, the US government initiated another program, known as the Merida Initiative, to help combat drug trafficking in Mexico. This program increased US security assistance to $1.4 billion over several years, which helped supply Mexican forces with "high-end equipment from helicopters to surveillance technology". Despite US aid, Mexican "narcogangs" continue to outnumber and outgun the Mexican Army, allowing for continued activities of drug cartels across the US–Mexico border.
== Health effects == Trifluoroacetic acid is a strong acid. TFA is harmful when inhaled, causes severe skin burns and is toxic for aquatic organisms even at low concentrations. Skin burns are severe, heal poorly and can be necrotic. Vapour fumes have an LC50 of 10.01 mg/L, tested on rats over 4 hours. Inhalation symptoms include mucus irritation, coughing, shortness of breath and possible formation of oedemas in the respiratory tract. Exposure damages the kidneys. TFA is also thought to be responsible for halothane-induced hepatitis. In 2024, the German Federal Institute for Risk Assessment (BfR) formally requested that the European Chemicals Agency (ECHA) reclassify TFA as "presumed" toxic to human reproduction, based on studies showing damage to animal fetuses. In June 2026, ECHA's Risk Assessment Committee (RAC) concluded that TFA fulfils the criteria for toxic to the reproduction class 1B, persistent, mobile and toxic (PMT) as well as very persistent and very mobile (vPvM). In July 2026, the European Food Safety Authority (EFSA) reduced the acceptable daily intake for TFA by 72%, from 0.05 mg/kg body weight/day down to 0.014. It also set the acute reference dose (ARfD) to 0.07 mg/kg body weight. These reductions were based on an assessment of new evidence, including changes in levels of the hormone thyroxine.
== Chemistry == Naltrexone, also known as N-cyclopropylmethylnoroxymorphone, is a derivative of oxymorphone (14-hydroxydihydromorphinone). It is specifically the derivative of oxymorphone in which the tertiary amine methyl substituent is replaced with methylcyclopropane.
Sources: en.wikipedia.org
It binds to and activates PPAR delta, a nuclear receptor that controls expression of genes related to fatty acid oxidation. This mechanism can alter energy metabolism in animal models. It is not a direct stimulant or fat-burning enzyme.
Early-stage trials examined lipid and glucose markers, but the development program was discontinued. Published human results are limited and do not support approved use for any indication. Claims of performance or health benefits remain unproven.
Yes. Laboratories use LC-MS/MS to detect GW501516 and its metabolites in urine. Detection depends on timing and sensitivity, but the substance is banned at all times.
No. Cardarine has not received approval for human therapeutic use in major jurisdictions. It remains an investigational compound.