The short version of nuclear receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-08. Anything still debated is marked as such rather than presented as settled.
Safety concerns emerged from long-term animal studies. In rodents given the compound for extended periods, researchers found an increased incidence of certain cancers, including liver and bladder tumors. These findings contributed to the discontinuation of clinical development. Whether similar risks apply to short-term or low-level exposure in humans is not established, and controlled human safety data are limited. The relevance of high-dose rodent carcinogenicity findings to human use remains a subject of debate.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
Laboratory studies indicate that GW501516 activates PPARδ, a nuclear receptor involved in fatty acid oxidation and energy metabolism. In rodent experiments, treated animals often showed increased endurance and reduced fat mass. These effects were observed under controlled conditions and do not establish safe or effective use in humans. The exact dose-response relationship in humans remains poorly characterized. Species differences in metabolism can affect how results translate across animals and people.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid metabolism |
| Preclinical effect | Increased fatty acid oxidation | Observed in rodent studies |
| Key safety signal | Tumors in rodents after long-term exposure | Contributed to halted clinical development |
| Human trial status | No approved product; development stopped | Limited short-term metabolic data |
| Sport regulatory status | Prohibited at all times | WADA hormone and metabolic modulators class |
Laboratory detection of cardarine typically involves sample preparation followed by chromatographic separation and mass spectrometric identification. Urine is the most common matrix for anti-doping tests, though blood and hair have also been explored. Methods can target the parent compound or its metabolites, depending on the expected window of detection. Reference standards are required for accurate quantification. Matrix effects and dilution can influence results, so laboratories use internal standards and validation protocols. The exact detection window varies with dose, route, and individual metabolism.
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.
Cardarine is a common name for the investigational chemical GW501516, also written GW-1516. It was developed as a peroxisome proliferator-activated receptor delta agonist for metabolic conditions such as dyslipidemia. Early research focused on lipid handling and energy use in skeletal muscle and other tissues. The compound was never approved as a medicine. In public discussion, it is often grouped with performance-enhancing substances, although its receptor target differs from that of anabolic steroids or selective androgen receptor modulators. Regulatory and health authorities have issued warnings about its use.
GW501516 acts on PPARδ, a nuclear receptor that helps regulate fatty acid oxidation and energy homeostasis. In animal studies, activation of this receptor was associated with increased endurance and changes in lipid metabolism. Human trials examined effects on blood lipids and other metabolic markers, but the compound did not advance to approval. Rodent studies later reported tumors in multiple tissues at doses used in those experiments. Whether those findings translate to human risk remains uncertain, and the clinical relevance of the animal data is still debated.
Regulatory bodies treat GW501516 as a prohibited substance in competitive sport. The World Anti-Doping Agency added it to the prohibited list, and it falls under classes covering metabolic modulators and hormone-related agents. It is not approved by drug regulators for human use, and it is not a lawful dietary supplement. Products sold under the cardarine name may contain unlisted ingredients or different compounds. Because no approved product exists, quality and identity are not guaranteed by pharmaceutical manufacturing standards.
Regulatory treatment varies, but cardarine is not approved as a medicine. Sports authorities list GW501516 as a prohibited substance, and it is banned at all times under the World Anti-Doping Agency code. Many countries restrict sales for human consumption, while online vendors market it as a research chemical. Such products may lack purity data, and their actual contents can differ from the label. Purchasing or possessing cardarine may carry legal consequences depending on jurisdiction. The compound is not a dietary supplement ingredient in regulated markets.
Clinical development stopped after rodent studies showed tumors at multiple sites. Whether those findings predict human cancer risk remains an open question, but they led sponsors to discontinue programs. Human safety data are limited to small, short-term studies that were not designed to assess cancer risk. Reported effects in those studies included changes in blood lipids, but the evidence is insufficient for medical use. Long-term consequences of nonmedical use are not well characterized. Questions about dose, duration, and individual susceptibility remain unresolved.
Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.
GW501516 acts as a selective agonist at PPARδ, a nuclear receptor that regulates transcription of genes involved in lipid handling and energy metabolism. Activation of PPARδ in preclinical models increases fatty acid oxidation, mitochondrial biogenesis, and exercise endurance in rodents. These effects have made the compound a subject of metabolic research and also a target for sport anti-doping rules. In humans, however, controlled studies are limited, and whether similar endurance or metabolic changes occur at tolerated exposures remains an open question. The receptor’s broad tissue distribution also means downstream effects may vary by organ and condition.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
==== Organorhodium compounds ==== Rhodium is known for its many organometallic derivatives. Rhodium(I) complexes are commonly used as catalysis, with a few being BINAP-Rh(I), DIPAMP-Rh(I), and BDPP-Rh(I). Cyclopentadienyl complexes of rhodium have been investigated as analogues of ferrocene. The parent is rhodocene, which participates in an unusual monomer-dimer equilibrium: Related cyclopentadienyl compounds include the Rh(I) and Rh(III) half-sandwich complexes (C5H5)Rh(CO)2 and Pentamethylcyclopentadienyl rhodium dichloride dimer (C5(CH3)5RhCl2)2. The latter compound is prepared by the reaction of rhodium trichloride trihydrate and pentamethylcyclopentadiene in hot methanol. A related but cationic family of hydrogenation catalysts arise from cyclooctadiene rhodium chloride dimer, Rh2Cl2(C8H12)2. The cyclooctadiene (C8H12) ligands are easily displaced, and this allows the easy introduction of chiral ligands, leading to asymmetric hydrogenations, including the Nobel Prize-winning route to the chiral drug L-DOPA. When treated with sodium borohydride and carbon monoxide, RhCl(P(C6H5)3)3 converts to the pentacoordinate complex RhH(CO)(P(C6H5)3)3, which is used commercially for the hydroformylation of alkenes. Despite its much higher cost, tris(triphenylphosphine)rhodium carbonyl hydride has displaced cheaper cobalt-based catalysts for this application.
=== Laboratory evaluation === Polycythemia is often initially identified on a complete blood count (CBC). The CBC is often repeated to evaluate for persistent polycythemia. If an etiology of polycythemia is unclear from history or physical, additional laboratory evaluation might include:
Flap endonuclease (FEN) is an endonuclease that catalyzes structure-specific cleavage. This cleavage is highly sensitive to mismatches and can be used to interrogate SNPs with a high degree of specificity In the basic Invader assay, a FEN called cleavase is combined with two specific oligonucleotide probes, that together with the target DNA, can form a tripartite structure recognized by cleavase. The first probe, called the Invader oligonucleotide is complementary to the 3’ end of the target DNA. The last base of the Invader oligonucleotide is a non-matching base that overlaps the SNP nucleotide in the target DNA. The second probe is an allele-specific probe which is complementary to the 5’ end of the target DNA, but also extends past the 3’ side of the SNP nucleotide. The allele-specific probe will contain a base complementary to the SNP nucleotide. If the target DNA contains the desired allele, the Invader and allele-specific probes will bind to the target DNA forming the tripartite structure. This structure is recognized by cleavase, which will cleave and release the 3’ end of the allele-specific probe. If the SNP nucleotide in the target DNA is not complementary to the allele-specific probe, the correct tripartite structure is not formed and no cleavage occurs. The Invader assay is usually coupled with fluorescence resonance energy transfer (FRET) system to detect the cleavage event. In this setup, a quencher molecule is attached to the 3’ end and a fluorophore is attached to the 5’ end of the allele-specific probe.
Sources: en.wikipedia.org
=== TNF inhibitors === Tumor necrosis factor inhibitors (TNFi) are a class of biologic drugs used in the treatment of ankylosing spondylitis. TNFi drugs, such as etanercept, infliximab, adalimumab, certolizumab, and golimumab, target the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). TNF-alpha plays a key role in the inflammatory process in ankylosing spondylitis. By blocking TNF-alpha, TNFi drugs help reduce inflammation, pain, and stiffness associated with AS, and may also slow down the progression of spinal damage.
Cupuaçu trees usually range from 5–15 m (16–49 ft) in height, though some can reach 20 m (66 ft). They have brown bark, and the leaves range from 25–35 cm (9.8–13.8 in) long and 6–10 cm (2.4–3.9 in) across, with 9 or 10 pairs of veins. As the trees mature, the leaves change from pink-tinted to green, and eventually they begin bearing fruit. Flowers of cupuaçu are structurally complex, and require pollination from biotic vectors. The majority of cupuaçu trees are self-incompatible, which can result in decreased pollination levels, and consequently, a decrease in fruit yields. Pollination can also be negatively affected by environmental conditions. Pollinators, which include chrysomelid weevils and stingless bees, are unable to fly between flowers in heavy rains.
=== Team indiscipline and fair play === In his early years at Arsenal, Wenger was scrutinised for the club's poor disciplinary record; Winter in 2003 described it as "little short of a crime-wave", while chairman Peter Hill-Wood admitted the players' conduct was unacceptable. Between September 1996 and February 2014, the team received 100 red cards. Wenger has often tried to defend his players, involved in controversial incidents on the field, by saying that he has not seen the incident; this is an option he resorts to when there is no "rational explanation" to defend him, and that he has the player's best interests in mind. However, in both 2004 and 2005, Arsenal topped the Premier League's Fair Play League tables for sporting behaviour and finished second in 2006. Their record as one of the most sporting clubs in the division continued up to 2009, where the team featured in the top four of the Fair Play table. Wenger's team again topped the fair play table for the 2009–10 season. In February 1999, Wenger offered Sheffield United a replay of their FA Cup fifth round match immediately after the match had finished, due to the controversial circumstances in which it was won. The decisive goal was scored by Overmars after Kanu failed to return the ball to the opposition; it was kicked into touch to allow Sheffield United's Lee Morris to receive treatment for an injury. Arsenal went on to win the replayed match 2–1.
Southern Association, previously Class A1 (1936–1945) Texas League, previously Class A1 (1936–1942; idle for three seasons during World War II) The Texas League remained in Double-A for the next 75 years. During this time, there were limited changes to leagues at the Double-A level:
Sources: en.wikipedia.org
Rodent studies reported increased endurance and fat oxidation after GW501516 exposure. Long-term studies also found higher rates of some tumors, which led to halted development.
Small short-term human trials examined metabolic markers such as lipids and glucose. The trials did not continue after rodent cancer findings, so long-term human safety is unknown.
Controlled human trials have not established a performance benefit. Anecdotal reports exist, but they are not reliable evidence.
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.