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.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Because cardarine is not an approved medicine, no pharmacopeial monograph defines its identity, purity, or storage requirements. Laboratories typically rely on in-house methods and reference standards when testing materials labeled as GW501516. Certificates of analysis may report purity and identity for a specific batch, but their scope varies and they do not guarantee safety or legal status. Independent verification can include high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. The distinction between research chemical labeling and human use is significant because quality standards and oversight differ.
Cardarine can be detected in biological samples and product materials using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method separates compounds by chromatography and identifies them by mass-to-charge transitions, allowing low-level detection in urine or blood. Sample preparation often involves enzymatic hydrolysis, solid-phase extraction, or protein precipitation. Certified reference materials and isotope-labeled internal standards improve quantification. Detection windows depend on metabolism, matrix, and assay sensitivity, so no single universal window applies.
| Property | Value | Notes |
|---|---|---|
| CAS Registry Number | 317318-70-0 | Unique identifier for the compound. |
| Chemical class | PPARδ agonist | Synthetic ligand for peroxisome proliferator-activated receptor delta. |
| Appearance | White to off-white solid | Typical form of research-grade material. |
| Solubility | Soluble in DMSO and ethanol | Poorly soluble in water. |
| Typical storage | -20°C | Recommended for long-term storage of stock solutions. |
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.
The compound is typically described as a laboratory compound rather than a therapeutic product. Published reports have explored its role in lipid disorders, insulin sensitivity, and exercise metabolism, yet no major drug regulator has approved it for medical use. Commercial samples sold under the cardarine name may vary in purity and identity. Analytical confirmation is therefore necessary when the material is discussed in scientific or regulatory contexts. Its classification as a prohibited substance in sport further shapes how it is studied and reported.
Cardarine is a common name for GW501516, a synthetic compound studied for its effects on lipid and glucose metabolism. It functions as an agonist at peroxisome proliferator-activated receptor delta, or PPARδ, a nuclear receptor that influences gene expression. The molecule is not a steroid, nor is it a selective androgen receptor modulator. It is also known in research and sports literature as GW-501516 and endurobol. Early laboratory work examined its metabolic activity in cell cultures and animal models.
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.
Cyanosulfidic scenarios are mechanisms for proto-metabolism proposed by the Eschenmoser and Sutherland groups. Research from the Eschenmoser group suggested that interactions between HCN and aldehydes can catalyze the formation of diaminomaleodinitrile (DAMN). Iterations of this cycle would generate multiple intermediate metabolites and key biomolecular precursors through functional group transformations by hydrolytic and redox processes. To expand upon this finding, the Sutherland group experimentally assessed the assembly of biomolecular building blocks from prebiotic intermediates and one-carbon feedstocks. They synthesized precursors of ribonucleotides, amino acids and lipids from the reactants of hydrogen cyanide, acetylene, acrylonitrile (product of cyanide and acetylene), and dihydroxyacetone (stable triose isomer of glyceraldehyde and phosphate). These reactions are driven by UV light and use hydrogen sulfide (H2S) as the primary reductant in these reactions. As each of these synthesis reactions was tested independently and some reactions require periodic input of additional reactants, these biomolecular precursors were not strictly generated through a one-pot synthesis expected of early Earth environments. In the same work, these authors argue that flow chemistry or the movement of reactants through water could generate the conditions favorable for the synthesis of these molecules.
==== 2008 financial crisis ==== In December 2007, the United States entered the longest post–World War II recession, caused by a housing market correction, a subprime mortgage crisis, soaring oil prices, and other factors. In February 2008, 63,000 jobs were lost, a five-year record, and in November, over 500,000 jobs were lost, which marked the largest loss of jobs in the United States in 34 years. The Bureau of Labor Statistics reported that in the last four months of 2008, 1.9 million jobs were lost. By the end of 2008, the U.S. had lost 2.6 million jobs. To aid with the situation, Bush signed a $170 billion economic stimulus package which was intended to improve the economic situation by sending tax rebate checks to many Americans and providing tax breaks for struggling businesses. The Bush administration pushed for significantly increased regulation of Fannie Mae and Freddie Mac in 2003, and after two years, the regulations passed the House but died in the Senate. Many Republican senators, as well as influential members of the Bush Administration, feared that the agency created by these regulations would merely be mimicking the private sector's risky practices. In September 2008, the 2008 financial crisis intensified, beginning with the Federal takeover of Fannie Mae and Freddie Mac followed by the bankruptcy of Lehman Brothers and a federal bailout of American International Group for $85 billion. Many economists and world governments determined that the situation had become the worst financial crisis since the Great Depression.
Sodium thiopental or pentobarbital: ultra-short-action barbiturate, an anesthetic agent used at a high dose that renders the person unconscious in less than 30 seconds. Depression of respiratory activity is one of the characteristic actions of this drug. Consequently, it will—even in the absence of the following two drugs—cause death due to lack of breathing, as happens with overdoses of opioids. Pancuronium bromide: non-depolarizing muscle relaxant, which causes complete, fast, and sustained paralysis of the striated skeletal muscles, including the diaphragm and the rest of the respiratory muscles; this would eventually cause death by asphyxiation. Potassium chloride: a potassium salt, which increases the blood and cardiac concentration of potassium to stop the heart via an abnormal heartbeat and thus cause death by cardiac arrest.
==== First two playoff appearances (1997–98) ==== The 1,000th hit of Bagwell's career was a home run on May 20, 1997, off Calvin Maduro, one of his two that game, in a 9–5 win over the Philadelphia Phillies. He was selected to the play in the All-Star Game. Exhibiting above-average speed and baserunning skills for a first baseman, Bagwell became the first full-time first baseman to join the 30–30 club, capping the 1997 season with 31 steals in 41 attempts. The only other first baseman to accomplish the 30–30 club is Joe Carter. Bagwell batted .286 and scored 109 runs. He finished second in the league with both 43 home runs and 135 RBI, his career high in RBI. He was third in the MVP balloting. He made the playoffs for the first time in 1997 when the Astros won the National League Central division, the club's first appearance in 11 years. The Astros faced the Atlanta Braves in the National League Division Series (NLDS), who swept them in three games. Bagwell, Biggio and Bell combined for two hits in 37 at bats. In 1998, Bagwell informed a Houston Chronicle reporter that he was using androstenedione (commonly referred to as "andro"), which at the time the United States Food and Drug Administration (FDA) classified it as a nutritional dietary supplement, finding it benign and authorized for non-medicinal purposes. It was considered a "weak" androgen steroid hormone and allegedly in widespread use around the sport at the time.[c] Bagwell hit his first career grand slam while tying a career-high six RBI against Cincinnati on September 8 in a 13–7 victory.
=== Overdose === Acute overdose is often manifested by nausea, weakness, slow heart rate, dizziness, low blood pressure, and abnormal heart rhythms. Plasma, serum, or blood concentrations of verapamil and norverapamil, its major active metabolite, may be measured to confirm a diagnosis of poisoning in hospitalized patients or to aid in the medicolegal investigation of fatalities. Blood or plasma verapamil concentrations are usually in a range of 50–500 μg/L in persons on therapy with the drug, but may rise to 1–4 mg/L in acute overdose patients and are often at levels of 5–10 mg/L in fatal poisonings.
Sources: en.wikipedia.org
Due to the rules, his case could have led to disqualification from the Seoul Olympics and suspension from competition for six months. The levels of the combined stimulants registered in the separate tests were 2 ppm, 4 ppm and 6 ppm. Lewis defended himself, claiming that he had accidentally consumed the banned substances. After the supplements that he had taken were analyzed to prove his claims, the USOC accepted his claim of inadvertent use, since a dietary supplement he ingested was found to contain "Ma huang", the Chinese name for Ephedra (ephedrine is known to help weight-loss). Fellow Santa Monica Track Club teammates Joe DeLoach and Floyd Heard were also found to have the same banned stimulants in their systems, and were cleared to compete for the same reason. The highest level of the stimulants Lewis recorded was 6 ppm, which was regarded as a positive test in 1988 but is now regarded as negative test. The acceptable level has been raised to ten parts per million for ephedrine and twenty-five parts per million for other substances. According to the IOC rules at the time, positive tests with levels lower than 10 ppm were cause of further investigation but not immediate ban.
== Avoiding categorical diagnosis == Current nosological approach does not provide a framework for internal (sub-threshold symptoms) or external (comorbidity) heterogeneity of the different diagnostic categories. The prevailing "Neo-Kraepelinian" diagnostic system solely accounts for a categorical diagnosis, therefore not allowing for the possibility of dual diagnosis. There has been substantial criticism to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), due to problems of diagnostic overlap, lack of clear boundaries between normality and disease, a failure to take into account findings from novel research and the lack of diagnostic stability over time.
== Toxicity == Modern medicine finds that mercury is inherently toxic, and that its toxicity is not due to the presence of impurities. While mercury does have anti-microbial properties, and used to be widely used in Western medicine, its toxicity does not warrant the risk of using it as a health product in most circumstances. The Centers for Disease Control and Prevention have also reported a number of cases of lead poisoning associated with Ayurvedic medicine. Other incidents of heavy metal poisoning have been attributed to the use of rasashastra compounds in the United States, and arsenic has also been found in some of the preparations, which have been marketed in the United States under trade names such as "AyurRelief", "GlucoRite", "Acnenil", "Energize", "Cold Aid", and "Lean Plus". Ayurvedic practitioners claim that these reports of toxicity are due to failure to follow traditional practices in the mass production of these preparations for sale, however there is ample evidence of mercury and lead toxicity. The government of India has ordered that Ayurvedic products must specify their metallic content directly on the labels of the product; however, M. S. Valiathan noted that "the absence of post-market surveillance and the paucity of test laboratory facilities [in India] make the quality control of Ayurvedic medicines exceedingly difficult at this time."
== Legal status == Dioxaphetyl butyrate is listed as an internationally controlled opioid under Schedule I of the 1961 Single Convention on Narcotic Drugs.[ref] In Australia, the Office of Drug Control lists it as a narcotic requiring import and export licensing and permits. In the United States it is a Schedule I Narcotic controlled substance with an ACSCN of 9621 and a 2013 annual aggregate manufacturing quota of zero.
Sources: en.wikipedia.org
In January 2020, astronomers reported that silicon carbide grains from the Murchison meteorite had been determined to be presolar material. The oldest of these grains was found to be 3 ± 2 billion years older than the 4.54 billion years age of the Earth and Solar System, making it the oldest material found on Earth to date.
== Track listing == "Sickman", "Junkhead", "Dirt" and "God Smack" are credited to Cantrell/Staley with no specification for lyrics or music. "Rain When I Die" is credited to Cantrell/Staley/Kinney/Starr, and it was later stated that Cantrell and Staley wrote the lyrics.
== Life == Biolik's parents emigrated to Canada from Poland after World War 2. Her roots in Poland are reflected in her coat of arms which was granted to her in 2003. Biolik was Canada's Consul General to Saint Petersburg, Russian Federation from 2001 to 2004. She is fluent in Russian and she encouraged sustainable development as a likely area for cooperation between Canada and Russia as they share a similar interest in the frozen north. Biolik was Ambassador Extraordinary and Plenipotentiary to Kazakhstan from 2004 to 2006, with concurrent accreditation to the Republic of Kyrgyzstan and the Republic of Tajikistan. In 2006 she outlined Canada's concerns about drug smuggling. She was briefed by Tajikistan ’s Drug Control Agency about their work. She wanted to ensure that Afghanistan's neighbours were aware as she saw that country's stability as key to the region. She was replaced in 2006 by Margaret Skok. Biolik was Canada's first Ambassador to Mongolia in 2008. Canada is the second largest investor in Mongolia after Russia - where she had previously been head of mission. She was thanked by Prime Minister Sükhbaataryn Batbold when she left. She was succeeded by J. Gregory Goldhawk. In 2011, she was appointed as the Regional Director of the Department of Foreign Affairs and International Trade's Vancouver Regional Office.
32S + n → 32P + p Neutron irradiation is performed in a nuclear reactor. The other main method used to synthesize radioisotopes is proton bombardment. The proton are accelerated to high energy either in a cyclotron or a linear accelerator.
Atoms and molecules of gas or liquid can be trapped on a solid surface in a process called adsorption. This is an exothermic process involving a release of heat, and heating the surface increases the probability that an atom will escape within a given time. At a given temperature
Sources: en.wikipedia.org
Cardarine is a common name for GW501516, a synthetic PPARδ agonist developed for research. It has not been approved as a medication in any country. It is classified as an unapproved drug and a prohibited substance in sport.
No. Cardarine is not an anabolic steroid; it belongs to a different chemical class that targets PPARδ. Steroids act primarily through androgen receptors, while cardarine acts through a nuclear receptor involved in metabolism.
Some rodent studies reported increased endurance and changes in fat metabolism after cardarine exposure. Long-term studies in animals also raised concerns about cancer in certain tissues. Human trial data are limited, so these findings cannot be directly translated to people.
Anti-doping laboratories typically use LC-MS/MS to detect GW501516 and its metabolites in urine. The method is sensitive and can identify the compound at low concentrations. Detection depends on sample timing, metabolism, and the specific assay.