This is a working overview of Nuclear receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-12 and is reviewed periodically as new material appears.
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.
PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.
Published studies have examined GW501516 in animal models of obesity, insulin resistance, and exercise endurance. Early human trials reportedly ended, and development was discontinued after preclinical findings raised concerns about cancer in some rodent studies. Regulatory agencies have not approved cardarine for any medical use. Its availability through non-pharmaceutical channels raises questions about identity, purity, and legal status that are separate from its laboratory pharmacology. Those questions are often addressed through analytical testing rather than assumptions about product labels.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic PPARδ agonist | Not a steroid or a selective androgen receptor modulator. |
| Common synonyms | Cardarine, GW501516, GW-501516, endurobol | Names vary by supplier and literature source. |
| Appearance | White to off-white powder | Consistent with many small-molecule research chemicals. |
| Solubility | Low in water; soluble in DMSO and ethanol | Often prepared in organic solvent for laboratory work. |
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid and energy metabolism. |
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.
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.
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.
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.
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.
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.
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.
H2S. Very small amounts of H2S, SF6, and probably any other sulfur containing gases, cause immediate and complete deactivation of the catalyst. It is not possible to regenerate a poisoned catalyst that has been deactivated by sulfur, by treating with either oxygen or hydrogen. If sulfur containing gases are present in the sample, a switching valve should be used either to bypass the catalyst, or to back-flush the column to vent after elution of CO2. Air or O2. Reports of oxygen poisoning seem to be rather rumors than real facts. Small amounts of air through a catalyst will not kill it but anything over about 5 cc/min will cause an immediate and continual degradation of the catalyst. Unsaturated hydrocarbons. Samples of pure ethylene cause immediate, but partial, degradation of the catalyst, evidenced by slight tailing of CO and CO2 peaks. The effect of 2 or 3 samples might be tolerable, but since it is cumulative, such gases should be backflushed or bypassed. Low concentrations do not cause any degradation. Samples of pure acetylene affect the catalyst much more severely than does ethylene. Low concentrations have no effect. Probably some carbonization with high concentrations of unsaturates occurs, resulting in the deposit of soot on the catalyst surface. It is likely that aromatics would have the same effect. Other compounds. Water has no effect on the catalyst, as well as various Freons and NH3. Here again, with NH3, there is conflicting evidence from some users, who have seen a degradation after several injections, but other researchers were not able to confirm it.
== Corneal keratocytes == Keratocytes are flattened cells found dispersed within the corneal stroma. The primary role of this sparse population of cells is thought to be in maintaining the extracellular matrix of collagen lamellae that surround them. However, keratocytes also play a defensive role during pathogenic invasion. They can be influenced by IL-1α (secreted by corneal epithelial cells) and tumor necrosis factor (TNF)-α to produce both IL-6 and defensins. Of these, the former is found to combine synergistically with other interleukins to increase co-stimulation of other immune aspects as well as increase antibody secretion. The latter, defensins, have a wide range of antimicrobial affects against bacteria, fungi, and viruses, as well as effects in accelerating healing of damaged epithelial cells. It has also been found that the presence of secreted defensins secreted by corneal keratocytes is correlated with cases of corneal transplant rejection, suggesting that these peptides may have a role in tissue rejection. Furthermore, keratocytes have also been found to secrete IL-8, which attracts neutrophils, in infections involving the herpes simplex virus.
=== Pharmacokinetics === When administered orally, ketoconazole is best absorbed at highly acidic levels, so antacids or other causes of decreased stomach acid levels will lower the drug's absorption. Absorption can be increased by taking it with an acidic beverage, such as cola. Ketoconazole is very lipophilic and tends to accumulate in fatty tissues.
Cold Cave would be featured on the soundtrack for Tony Hawk's Pro Skater 5 later that year, and two of their songs were selected by Hawk for inclusion on 2018's Tony Hawk's Skate Jam. In mid-February 2016, a single called "Nothing Is True But You" was released. In Spring, Max G. Morton, who played keyboards for a short portion of the band's early days and also collaborated with Eisold on prose and publishing via the singer's own Heartworm Press, rejoined the band. At end of August 2016, the band shared another single, an almost cacophonic track called "The Idea of Love". In September, they embarked on a domestic mini-tour together with dark electropop act TR/ST. In late September 2017, Cold Cave released a single called "Glory", a track reminiscent of early New Order. The video accompanying the track revealed a full live band featuring, besides the ever-present Eisold and Amy Lee, steady touring member Max G. Morton, Nils Bue (bass/guitar) and Ryan McMahon (drums). The band kicked off a small US tour before heading to Europe to support The Jesus and Mary Chain until mid-October. In early April 2018, the band premiered another song, "You & Me & Infinity", and announced a 26-date North American Spring tour with Choir Boy and Black Marble. At the end of the month, a new EP bearing the title of their latest single was made available digitally. In November of the same year the band headed overseas for a string of selected European dates, again with support from Choir Boy.
Sources: en.wikipedia.org
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a cholesterol test, are often grouped together into one test panel called a blood panel or blood work. Blood tests are often used in health care to determine physiological and biochemical states, such as disease, mineral content, pharmaceutical drug effectiveness, and organ function. Typical clinical blood panels include a basic metabolic panel or a complete blood count. Blood tests are also used in drug tests to detect drug abuse.
Polymerase chain reaction (PCR) is the primary gene amplification technique that has revolutionized modern biochemistry. Polymerase chain reaction was developed by Kary Mullis in 1983. There are four steps to a proper polymerase chain reaction: 1) denaturation 2) extension 3) insertion (of gene to be expressed) and finally 4) amplification of the inserted gene. These steps with simple illustrative examples of this process can be seen in the image below and to the right of this section. This technique allows for the copy of a single gene to be amplified into hundreds or even millions of copies and has become a cornerstone in the protocol for any biochemist that wishes to work with bacteria and gene expression. PCR is not only used for gene expression research but is also capable of aiding laboratories in diagnosing certain diseases such a lymphomas, some types of leukemia, and other malignant diseases that can sometimes puzzle doctors. Without polymerase chain reaction development, there are many advancements in the field of bacterial study and protein expression study that would not have come to fruition. The development of the theory and process of polymerase chain reaction is essential but the invention of the thermal cycler is equally as important because the process would not be possible without this instrument. This is yet another testament to the fact that the advancement of technology is just as crucial to sciences such as biochemistry as is the painstaking research that leads to the development of theoretical concepts.
=== Medical imaging === A physician may diagnose an inguinal hernia, as well as the type, from medical history and physical examination. For confirmation or in uncertain cases, medical ultrasonography is the first choice of imaging, because it can both detect the hernia and evaluate its changes with for example pressure, standing and Valsalva maneuver. When assessed by ultrasound or cross sectional imaging with CT or MRI, the major differential in diagnosing indirect inguinal hernias is differentiation from spermatic cord lipomas, as both can contain only fat and extend along the inguinal canal into the scrotum. On axial CT, lipomas originate inferior or lateral to the cord, and are located inside the cremaster muscle, while inguinal hernias lie anteromedial to the cord and are not intramuscular. Large lipomas may appear nearly indistinguishable as the fat engulfs anatomic boundaries, but they do not change position with coughing or straining.
Sources: en.wikipedia.org
Cardarine is a common name for GW501516, a synthetic PPARδ agonist. It is not a steroid or a selective androgen receptor modulator. It was developed and studied as a research compound for metabolic pathways.
It binds to and activates PPARδ, a nuclear receptor that regulates genes related to fatty acid oxidation and energy use. This activation alters transcription in tissues such as skeletal muscle and liver. The full range of downstream effects in humans is not fully established.
No, cardarine is not known to occur naturally in plants, animals, or humans. It is a synthetic molecule produced for laboratory research. Products labeled as cardarine should therefore be treated as manufactured chemicals with variable purity.
Cardarine is commonly known as GW501516 or GW-1516. These names refer to the same synthetic compound. It is not a brand-name approved medicine.