This is a working overview of Nuclear receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
Early clinical research explored GW501516 for lipid disorders, obesity, and diabetes. Some short-term human studies reported changes in HDL cholesterol, LDL cholesterol, and triglycerides. The development program was discontinued after rodent studies showed dose-dependent tumor formation in multiple tissues, including liver, bladder, stomach, and skin. These findings raised concerns about long-term cancer risk in humans. Because human exposure data are limited, the clinical significance of the rodent tumors remains uncertain.
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Prohibited in sport | Listed by WADA as a metabolic modulator. |
| Approved medical use | None in major jurisdictions | Not a registered drug. |
| Common test matrix | Urine | Most anti-doping samples use urine. |
| Typical detection method | LC-MS/MS | Detects parent compound and metabolites. |
| Reference standard storage | -20 °C, desiccated | Typical for analytical standards. |
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.
Cardarine is a common name for GW501516, a synthetic compound developed in the 1990s through research collaborations involving GlaxoSmithKline. It belongs to a class of molecules known as peroxisome proliferator-activated receptor delta agonists. Early studies explored its effects on lipid metabolism and energy expenditure in animal models. The compound was never approved as a human medicine, and clinical development was discontinued. In the years since, it has appeared in fitness and bodybuilding communities as a performance-enhancing substance. Regulatory agencies classify it as an unapproved drug.
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.
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.
According to a recent patent application, yields of up to 95% are obtained with the same starting materials in toluene in the presence of potassium methoxide. It is subject to keto-enol tautomerism and exists predominantly enol when dissolved. Upon UV radiation, it may convert to keto form, while converting back to enol form after placing in dark.
In 1941, at age 40, Pauling was diagnosed with Bright's disease, a renal disease. Following the recommendations of Thomas Addis, who actively recruited Ava Helen Pauling as "nutritionist, cook, and eventually as deputy 'doctor'", Pauling believed he was able to control the disease with Addis's then-unusual low-protein salt-free diet and vitamin supplements. Thus Pauling's initial – and intensely personal – exposure to the idea of treating disease with vitamin supplements was positive. In 1965, Pauling read Niacin Therapy in Psychiatry by Abram Hoffer and theorized vitamins might have important biochemical effects unrelated to their prevention of associated deficiency diseases. In 1968, Pauling published a brief paper in Science entitled "Orthomolecular psychiatry", giving a name to the popular but controversial megavitamin therapy movement of the 1970s, and advocating that "orthomolecular therapy, the provision for the individual person of the optimum concentrations of important normal constituents of the brain, may be the preferred treatment for many mentally ill patients." Pauling coined the term "orthomolecular" to refer to the practice of varying the concentration of substances normally present in the body to prevent and treat disease. His ideas formed the basis of orthomolecular medicine, which is not generally practiced by conventional medical professionals and has been strongly criticized. In 1973, with Arthur B.
On March 10, 2014, the first Dunkin' Donuts/Baskin-Robbins combination store in Southern California opened in Ramona. This is Dunkin' Donuts' third California shop to open, following shops in Barstow and on Camp Pendleton. Since March 2014, Dunkin' Donuts has opened several additional locations throughout California, including the Los Angeles area. Dunkin' Donuts shops opened in the San Francisco Bay Area in Walnut Creek, Half Moon Bay, and American Canyon in 2016, as well as South San Francisco and Fremont, in 2017.
=== Nutritional fortification === Breakfast cereals may be fortified with dietary minerals and vitamins. For example, breakfast cereal in Canada may be fortified with specific micronutrient amounts per 100 grams of cereal, including thiamin, (2.0 mg), niacin (4.8 mg), and vitamin B6 (0.6 mg), among others.
Sources: en.wikipedia.org
=== Epsilon (ε) opioid receptor === Another postulated opioid receptor is the ε opioid receptor. The existence of this receptor was suspected after the endogenous opioid peptide beta-endorphin was shown to produce additional actions that did not seem to be mediated through any of the known opioid receptors. Activation of this receptor produces strong analgesia and release of met-enkephalin; a number of widely used opioid agonists, such as the μ agonist etorphine and the κ agonist bremazocine, have been shown to act as agonists for this effect (even in the presence of antagonists to their more well known targets), while buprenorphine has been shown to act as an epsilon antagonist. Several selective agonists and antagonists are now available for the putative epsilon receptor; however, efforts to locate a gene for this receptor have been unsuccessful, and epsilon-mediated effects were absent in μ/δ/κ "triple knockout" mice, suggesting the epsilon receptor is likely to be either a splice variant derived from alternate post-translational modification, or a heteromer derived from hybridization of two or more of the known opioid receptors.
In 1992, Volkman et al. reported the first evidence of dinosterol in a laboratory culture of a marine diatom Navicula sp., indicating that diatoms may be a source of dinosterol in marine sediments. Within this diatom, 4-methyl sterols comprised less than 0.7% abundance, whereas these sterols are much more abundant in dinoflagellates. Notably, the stereochemistry of the C-24 alkyl substituent in the sterols of diatoms is 24α, whereas in dinoflagellates it is 24β. If the C-24 alkylated sterols in Navicula (CS-46c) are the epimers of dinosterol and dinostanol, then this may be used to discriminate between dinoflagellate and diatom sources of "dinosterol" in sediments. However, the C-24 substituents in steroidal compounds rapidly isomerize in sediments such that a mixture of C-23 and C-24 isomers is formed. Therefore, once the sediment reaches a certain thermal maturity, the stereochemistry at the C-24 position can no longer be used to distinguish between diatom and dinoflagellate sources of dinosterol.
For voluntary and charitable services to the My Name'5 Doddie Foundation. Helen Ruth Waite. Deputy Director, Family Support, Department for Education. For services to Education. Professor Mark Watson-Gandy. Chair, Biometrics and Forensics Ethics Group. For Public and Voluntary Services. Dr. David Clark Watt. Chair, Fife College. For services to the Economy, to Sport and to Education. Lieutenant Colonel (Rtd) David Ian Whimpenny. Lately Board Trustee, The Royal British Legion. For Voluntary Service. Stephen John Whitton. Head, Border Force Maritime Command, Home Office. For services to Maritime Border Security. Professor Mark Harvey Wilcox. Lately National Clinical Director for Infection Prevention and Control, NHS England and Chair, SAGE Sub-Committee on Hospital Onset Covid Infection. For services to Healthcare, particularly during Covid-19. Howard Wilkinson. Chairman, League Managers Association. For services to Association Football and to Charity. Yvonne Marie Wilks-O'Grady. Philanthropist and Co-Founder, Roots Magazine. For services to Media, to Publishing and to Charity. Professor Bryan Williams. Chair of Medicine, University College London and lately Director of Research, University College London Hospitals NHS Foundation Trust. For services to Medicine. Robert John Williamson, DL. Chief Executive, The Community Foundation Tyne and Wear and Northumberland. For Voluntary and Charitable Services. Stephen John Willmer. Lately Deputy Head France, Security Policy and Operations, Ministry of Defence. For services to Defence and to International Relations. Dr.
Detrital zircon geochronology is a scientific technique for understanding the age and provenance of sedimentary deposits. To determine the age of zircons deposited within a specific sedimentary unit, mass spectrometry is used to measure the abundance of radioisotopes in the grains, most commonly the uranium–lead ratio. Zircon is a common accessory or trace mineral constituent of most granite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircons contain trace amounts of uranium and thorium and can be dated using several modern analytical techniques. Detrital zircon geochronology has become increasingly popular in geological studies from the 2000s mainly due to the advancement in radiometric dating techniques. Detrital zircon age data can be used to constrain the maximum depositional age, determine provenance, and reconstruct the tectonic setting on a regional scale.
Famotidine, sold under the brand name Pepcid among others, is a histamine H2 receptor antagonist medication that decreases stomach acid production. It is used to treat peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellison syndrome. It is taken by mouth or by injection into a vein. It begins working within an hour. Common side effects include headache, abdominal pain, diarrhea or constipation, and dizziness. Serious side effects may include pneumonia and seizures. Use in pregnancy appears safe but has not been well studied, while use during breastfeeding is not recommended. Famotidine was patented in 1979 and came into medical use in 1985. It is available as a generic medication. In 2023, it was the 33rd most commonly prescribed medication in the United States, with more than 16 million prescriptions.
Sources: en.wikipedia.org
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.
Anti-doping laboratories use LC-MS/MS to detect GW501516 and its metabolites, usually in urine. The method can identify the parent compound at low concentrations. Detection windows vary with dose and individual factors.
No, cardarine has no approved medical uses in major jurisdictions. Early research explored metabolic conditions, but those programs were discontinued. It is not a registered treatment for any disease.
It targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not act primarily on androgen receptors. This distinction separates it from SARMs.