Nuclear receptor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-20. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Visual description for typical solid reference material. |
| Solubility | Poorly soluble in water; soluble in DMSO | Solubility depends on solvent, purity, and form. |
| Storage | Cool, dry, protected from light | Long-term storage often uses low temperature and desiccant. |
| Common analytical method | LC-MS/MS | Used for detection and quantification in biological matrices. |
| Common synonyms | GW-501516; GW501516; endurobol | Naming varies among literature, vendors, and databases. |
== Selected publications == Bounous, G; Molson, JH (2003). "The antioxidant system". Anticancer Research. 23 (2B): 1411–5. PMID 12820403. Kennedy, RS; Konok, GP; Bounous, G; Baruchel, S; Lee, TD (1995). "The use of a whey protein concentrate in the treatment of patients with metastatic carcinoma: A phase I-II clinical study". Anticancer Research. 15 (6B): 2643–9. PMID 8669840. Bounous, Gustavo; Somersall, Allan (April 1999). Breakthrough In Cell-Defense. GOLDENeight Publishing. ISBN 978-1-890412-86-9.
=== Atomic and molecular physics === Some atomic energy levels are metastable. Rydberg atoms are an example of metastable excited atomic states. Transitions from metastable excited levels are typically those forbidden by electric dipole selection rules. This means that any transitions from this level are relatively unlikely to occur. In a sense, an electron that happens to find itself in a metastable configuration is trapped there. Since transitions from a metastable state are not impossible (merely less likely), the electron will eventually decay to a less energetic state, typically by an electric quadrupole transition, or often by non-radiative de-excitation (e.g., collisional de-excitation). This slow-decay property of a metastable state is apparent in phosphorescence, the kind of photoluminescence seen in glow-in-the-dark toys that can be charged by first being exposed to bright light. Whereas spontaneous emission in atoms has a typical timescale on the order of 10−8 seconds, the decay of metastable states can typically take milliseconds to minutes, and so light emitted in phosphorescence is usually both weak and long-lasting.
=== Rule of 13 === The Rule of 13 is a simple procedure for tabulating possible chemical formula for a given molecular mass. The first step in applying the rule is to assume that only carbon and hydrogen are present in the molecule and that the molecule comprises some number of CH "units" each of which has a nominal mass of 13. If the molecular weight of the molecule in question is M, the number of possible CH units is n and
Its vessels serve routes to and from Bacolod, Batangas, Butuan, Cagayan de Oro, Caticlan, Cebu, Coron, Davao, Dipolog, Dumaguete, General Santos, Iloilo, Manila, Odiongan, Ozamiz, Puerto Princesa, Roxas, Siargao, Tagbilaran, and Zamboanga.
Sources: en.wikipedia.org
== Politics and administration == Le Havre is one of two sub-prefectures of Seine-Maritime and the second largest subprefecture in France after Reims. It is the capital of the Arrondissement of Le Havre which includes 168 communes. It is also the largest member of the Le Havre Seine Métropole.
== P == Pier Paolo Pandolfi (b. 1963). Italian geneticist and molecular biologist at the Desert Research Institute, Reno, known for work on pseudogenes. Jakub Karol Parnas (1884–1949). Polish-Soviet biochemist at the University of Lviv, who discovered (with Gustav Embden and Otto Fritz Meyerhof), the glycolytic pathway. Linus Pauling (1901–1994). American chemist and biochemist at Caltech, known for many advances in chemistry, including the α-helical structure of proteins. Nobel Prize in Chemistry (1954). Louis Pasteur FRS (foreign associate) (1822–1895). French biologist, microbiologist and chemist at the Pasteur Institute (Paris), who made many contributions to microbiology, stereochemistry and medicine, including the first vaccines for rabies and anthrax. Natl. Acad. Sci. USA (foreign associate). Arthur Peacocke (1924–2006). British Anglican theologian and biochemist at the University of Oxford. Max Perutz FRS (1914–2002). Austrian-British molecular biologist and X-ray crystallographer at Cambridge University, who solved the crystal structure of haemoglobin. Nobel Prize in Chemistry (1962). Samuel Victor Perry FRS (1918–2009). British biochemist at the University of Birmingham, pioneer in the biochemistry of muscle. Gösta Pettersson (b. 1937). Swedish biochemist at the University of Lund, expert on enzyme kinetics. Antoinette Pirie (1905–1991), British biochemist, ophthalmologist, and educator. Norman Wingate Pirie FRS (1907–1997), British biochemist and virologist. Rosalind Pitt-Rivers (1907–1990).
=== Electromagnetic flux === In radio astronomy, the unit of electromagnetic flux is the jansky (symbol Jy), equivalent to 10−26 watts per square metre per hertz (= 10−26 kg/s2 in base units, about 8.8×10−31 BTU/ft2). It is named after the pioneering radio astronomer Karl Jansky. The brightest natural radio sources have flux densities of the order of one to one hundred jansky.
Where k is a constant that depends on muscle mass, which itself varies with a child's age: In first year of life, for pre-term babies k=0.33 and for full-term infants k=0.45 For infants and children of age 1 to 12 years, k=0.55. The method of selection of the constant k has been questioned as being dependent upon the gold-standard of renal function used (i.e. inulin clearance, creatinine clearance, etc.) and also may be dependent upon the urinary flow rate at the time of measurement. In 2009 the formula was updated to use standardized serum creatinine (recommend k=0.413) and additional formulas that allow improved precision were derived if serum cystatin C is measured in addition to serum creatinine.
Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. Leeuwenhoek did not recognize bacteria as a distinct category of microorganisms, and referred to all microorganisms, including bacteria, protists, and microscopic animals, as animalcules. He published his observations in a series of letters to the Royal Society of London. His observations also included protozoans. The German Ferdinand Cohn began studying bacteria in 1870 and is also said to be a founder of bacteriology, as he was the first to classify bacteria into groups based on their cell shapes. He defined bacteria as "chlorophyll-free cells of spherical, oblong, or cylindrical form, sometimes twisted or bent, which multiply exclusively by transverse division and occur either isolated or in cell families," and placed them in the plant kingdom. He also discovered heat-resistant bacterial endospores Louis Pasteur demonstrated in 1859 that microorganisms cause the fermentation process, and that this growth is not due to spontaneous generation (yeasts and molds, commonly associated with fermentation, are not bacteria, but rather fungi). Along with his contemporary Robert Koch, Pasteur was an early advocate of the germ theory of disease. Between 1880 and 1881 Pasteur produced two successful vaccinations for animals against diseases caused by bacteria. The importance of bacteria was recognized as it led to a study of disease prevention and treatment of diseases by vaccines.
Sources: en.wikipedia.org
=== BPI lawsuit === On September 13, 2012, BPI announced that it filed a $1.2 billion lawsuit, Beef Products, Inc. v. American Broadcasting Companies, Inc., against ABC News; three reporters (Diane Sawyer, Jim Avila and David Kerley) and others, claiming ABC News made nearly "200 false, misleading and defamatory statements, repeated continuously during a month-long disinformation campaign", engaged in "product and food disparagement, and tortious interference with business relationships". BPI called the ABC News series a "concerted disinformation campaign" against LFTB. ABC News denied BPI's claims, and called the lawsuit without merit. ABC News sought to have the case removed from South Dakota state court to federal court. In June 2013, a federal judge sent the lawsuit back to state court. On March 27, 2014, South Dakota state court Judge Cheryle Gering rejected ABC's motion to dismiss, and allowed the defamation suit to move forward. Diane Sawyer's motion for summary judgment was granted and she was dismissed. The trial of the case began June 5, 2017, in Elk Point, South Dakota. The trial, in a courthouse remodeled for the occasion, was expected to take 8 weeks, but was settled after three weeks. The court ruled that BPI is a public figure; thus, proof of "actual malice" is required to support a verdict of defamation. ABC was represented by Williams & Connolly, BPI by Winston & Strawn. South Dakota has a food disparagement law which may have permitted triple damages to $5.7 billion had there been a verdict for the plaintiff.
== History == In 1943, diphenhydramine was discovered by chemist George Rieveschl and one of his students, Fred Huber, while they were conducting research into muscle relaxants at the University of Cincinnati. Huber first synthesized diphenhydramine. Rieveschl then worked with Parke-Davis to test the compound, and the company licensed the patent from him. In 1946, it became the first prescription antihistamine in the United States approved by the FDA. In the 1960s, diphenhydramine was found to weakly inhibit reuptake of the neurotransmitter serotonin. This discovery led to a search for viable antidepressants with similar structures and fewer side effects, culminating in the invention of fluoxetine (Prozac), a selective serotonin reuptake inhibitor (SSRI). A similar search had previously led to the synthesis of the first SSRI, zimelidine, from brompheniramine, also an antihistamine. In 1975, diphenhydramine was still available only by prescription in the US and required medical supervision.
=== Modulated drug release and zero-order drug release === Many scientists worked to create oral formulations that could maintain a constant drug level because of the ability of drug release at a zero-order rate blood's concentration. However, a few physiological restrictions made it challenging to create such oral formulations. First, because the lower parts of the intestine have a decreased capacity for absorption, the medication absorption typically declines as an oral formulation moves from the stomach to the intestine. The decreased drug amount released from the formulation over time frequently made this condition worse. Phenylpropanolamine HCl release from was the only instance of sustaining consistent blood concentration for roughly 16 hours.
therapeutic area) might be tempted or encouraged to expand their engagement with that CRO into other, unrelated areas; however, caution is required as CROs are always seeking to expand their experience and success in one area cannot reliably predict success in unrelated areas that might be new to the organization.
Sources: en.wikipedia.org
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.
Most methods use liquid chromatography with tandem mass spectrometry. Urine is common in anti-doping testing, and blood or plasma may be used in research.
Typical guidance is cool, dry, dark storage, often at low temperature and with desiccant. Stability data are limited, so storage conditions should be verified for each batch or supplier.
Cardarine is an investigational synthetic compound that acts as a PPARδ agonist. It is also known as GW501516 and has been studied mainly in preclinical research. It is not an approved medicine.