nuclear receptor is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-04-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
GW501516 acts as an agonist at the peroxisome proliferator-activated receptor delta, a nuclear receptor that regulates gene expression. Activation shifts transcription toward genes involved in fatty acid uptake, oxidation, and energy expenditure. The compound does not bind the androgen receptor and therefore differs from anabolic steroids and SARMs. In rodent models, this metabolic shift has been linked to increased running endurance and reduced fat accumulation. The exact downstream pathways in humans remain incompletely characterized.
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.
Anti-doping laboratories identify GW501516 and related metabolites using liquid chromatography coupled with tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be analyzed. The method targets the parent compound and phase I and phase II metabolites, which extend the detection window. Because the substance is prohibited at all times, athletes can be tested outside competition. Detection limits and windows depend on the assay, sample type, and individual metabolism.
Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ | Nuclear receptor; not androgen receptor |
| Studied indications | Dyslipidemia; obesity; diabetes | Early clinical research; development discontinued |
| Rodent toxicity | Tumor formation in multiple tissues | Dose-dependent findings in some studies |
| Human approval | None | No approved therapeutic use |
| Typical analytical method | LC-MS/MS | Used for identity and quantification |
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.
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.
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.
Activation of PPARδ changes transcription of genes involved in fatty acid transport, mitochondrial function, and skeletal muscle fuel preference. In rodent studies, pharmacological PPARδ activation was associated with increased endurance and altered body composition. These findings generated interest in performance enhancement, but species differences and study designs limit direct extrapolation to humans. Small human trials were conducted in the 2000s and later discontinued. The extent to which cardarine produces similar metabolic or performance effects in people remains an open question.
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 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.
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.
==== Cap-independent initiation ==== The best-studied example of cap-independent translation initiation in eukaryotes uses the internal ribosome entry site (IRES). Unlike cap-dependent translation, cap-independent translation does not require a 5' cap to initiate scanning from the 5' end of the mRNA until the start codon. The ribosome can localize to the start site by direct binding, initiation factors, and/or ITAFs (IRES trans-acting factors) bypassing the need to scan the entire 5' UTR. This method of translation is important in conditions that require the translation of specific mRNAs during cellular stress, when overall translation is reduced. Examples include factors responding to apoptosis and stress-induced responses.
=== Humanitarian work === Collins is a supporter of animal rights. She has appeared in numerous campaigns for the animal rights organisation PETA. In 2013, she posed naked for the "I'd Rather Go Naked Than Wear Fur" campaign. In 2020, Collins was photographed in a bathtub to highlight the fact that marine animals are separated from their families and confined to concrete tanks. In 2021, she posed with a skinned fox as she backed the campaign to end the fur trade in the United Kingdom. Addressing then prime minister Boris Johnson, Collins said "Take it from an icon, Boris – no one needs fur in their wardrobe. Do the right thing – ban fur imports and sales. Let's wear our skin and let the animals keep theirs." Speaking on her podcast, Collins expressed her interest in becoming a humanitarian and said she wishes to promote conservation and animal welfare to the next generation. In November 2022, Collins opened a newly refurbished Cats Protection adoption centre in Chelmsford, during which she was given a tour and the opportunity to name one of the cats, which she named after Mr. Mistoffelees from Cats. Following the re-opening, Collins said she was "putting out a plea to help these amazing people give cats a home". In March 2023, Collins assisted with the launch of the Be A Cat Cafe in Soho, a pop-up experience from cat food brand Felix. Attending the event, Collins said "I'm here for cattitude and think that if people tried being more like a cat, they'd be a lot more chilled out and relaxed".
Food and Drug Administration (FDA) has issued a black box warning for suicidal behavior/ideation. Similar warnings have been issued in Australia. Unlike stimulant medications, atomoxetine does not have misuse liability or the potential to cause withdrawal effects upon abrupt discontinuation. Atomoxetine has been found to directly inhibit hERG potassium currents with an IC50Tooltip half-maximal inhibitory concentration of 6,300 nM, which has the potential to cause arrhythmia. No substantial QTc interval changes were observed in a clinical study of atomoxetine in CYP2D6 poor metabolizers. However, small changes could not be ruled out, and there was a slight but significant increase in QTc interval with higher atomoxetine concentrations. QT prolongation has been reported with atomoxetine at therapeutic doses and in overdose; it is suggested that atomoxetine not be used with other medications that may prolong the QT interval, concomitantly with CYP2D6 inhibitors, and caution to be used in poor metabolizers. Unlike α2-adrenergic receptor agonists such as guanfacine and clonidine, atomoxetine's use can be abruptly stopped without significant withdrawal symptoms being observed.
The original liquid formulation without EDTA was returned to the market in the US in May 2008. In 2009, Genzyme acquired the rights to Leukine from Bayer, including the manufacturing facility in the Seattle area. In March 2018 the label was extended to use as a countermeasure for acute radiation syndrome. In February 2018, Partner Therapeutics, Inc. acquired the global rights to develop, manufacture, and commercialize Leukine (sargramostim) from Sanofi.
Sources: en.wikipedia.org
== Mission and Research Strategy == The mission of TBRI is targeted towards the control, the diagnosis and management of endemic diseases and their complications especially those affecting the liver, the gastrointestinal and the urinary tracts, mainly as result of schistosomiasis and viral hepatitis, this is to meet the social, economic and technological needs of Egypt and the regional area. The Institute adopts an integrated strategy based on six research programs that can cope with and fulfill this objective:
=== Ion mobility spectrometry === Explosive detection using ion mobility spectrometry (IMS) is based on velocities of ions in a uniform electric field. There are some variant to IMS such as Ion trap mobility spectrometry (ITMS) or Non-linear dependence on ion mobility (NLDM) which are based on IMS principle. The sensitivity of devices using this technology is limited to pg levels. The technology also requires the ionization of sample explosives which is accomplished by a radioactive source such as nickel-63 or americium-241. This technology is found in most commercially available explosive detectors such as the GE VaporTracer, Smith Sabre 4000 and Russian built MO-2M and MO-8. The presence of radioactive materials in these equipments cause regulatory hassles and requires special permissions at customs ports. These detectors cannot be field serviced and may pose radiation hazard to the operator if the casing of the detector cracks due to mishandling. Bi-yearly checks are mandatory on such equipment in most countries by regulating agencies to ensure that there are no radiation leaks. Disposal of these equipments is also controlled owing to the high half-life of the radioactive material used. Electrospray ionization, mobility analysis (DMA) and tandem mass spectrometry (MS/MS) is used by SEDET (Sociedad Europea de Detección) for the “Air Cargo Explosive Screener (ACES)”, targeted to aviation cargo containers currently under development in Spain.
Nemonapride, also previously known as emonapride and sold under the brand name Emilace, is an atypical antipsychotic which is used in the treatment of schizophrenia. It is taken by mouth. Side effects of nemonapride include akathisia, dystonia, hypokinesia, tremor, hypersalivation, and hyperprolactinemia, among others. The drug acts as a dopamine D2, D3, and D4 receptor antagonist. To a lesser extent, it is also a serotonin 5-HT1A receptor partial agonist. Structurally, nemonapride is a benzamide derivative and is related to sulpiride and other benzamides. Nemonapride was introduced for medical use in either 1991 or 1997. It was developed and marketed by Yamanouchi Pharmaceuticals. The drug is approved only in Japan and China.
Sources: en.wikipedia.org
The reinforcing effects of alcohol consumption are mediated by acetaldehyde generated by catalase and other oxidizing enzymes such as cytochrome P-4502E1 in the brain. Although acetaldehyde has been associated with some of the adverse and toxic effects of ethanol, it appears to play a central role in the activation of the mesolimbic dopamine system. Ethanol's rewarding and reinforcing (i.e., addictive) properties are mediated through its effects on dopamine neurons in the mesolimbic reward pathway, which connects the ventral tegmental area to the nucleus accumbens (NAcc). One of ethanol's primary effects is the allosteric inhibition of NMDA receptors and facilitation of GABAA receptors (e.g., enhanced GABAA receptor-mediated chloride flux through allosteric regulation of the receptor). At high doses, ethanol inhibits most ligand-gated ion channels and voltage-gated ion channels in neurons as well. With acute alcohol consumption, dopamine is released in the synapses of the mesolimbic pathway, in turn heightening activation of postsynaptic D1 receptors. The activation of these receptors triggers postsynaptic internal signaling events through protein kinase A, which ultimately phosphorylate cAMP response element binding protein (CREB), inducing CREB-mediated changes in gene expression. With chronic alcohol intake, consumption of ethanol similarly induces CREB phosphorylation through the D1 receptor pathway, but it also alters NMDA receptor function through phosphorylation mechanisms; an adaptive downregulation of the D1 receptor pathway and CREB function occurs as well.
=== Compensatory mutations in RNA === As the function of a RNA molecule is dependent on its structure, the structure of RNA molecules is evolutionarily conserved. Therefore, any mutation that alters the stable structure of RNA molecules must be compensated by other compensatory mutations. In the context of RNA, the sequence of the RNA can be considered as ' genotype' and the structure of the RNA can be considered as its 'phenotype'. Since RNAs have relatively simpler composition than proteins, the structure of RNA molecules can be computationally predicted with high degree of accuracy. Because of this convenience, compensatory mutations have been studied in computational simulations using RNA folding algorithms.
lack of resistance to permanent deformation, resisting only relative rates of deformation in a dissipative, frictional manner, and the ability to flow (also described as the ability to take on the shape of the container). These properties are typically a function of their inability to support a shear stress in static equilibrium. By contrast, solids respond to shear either with a spring-like restoring force—meaning that deformations are reversible—or they require a certain initial stress before they deform (see plasticity). Solids respond with restoring forces to both shear stresses and to normal stresses, both compressive and tensile. By contrast, ideal fluids only respond with restoring forces to normal stresses, called pressure: fluids can be subjected both to compressive stress—corresponding to positive pressure—and to tensile stress, corresponding to negative pressure. Solids and liquids both have tensile strengths, which when exceeded in solids creates irreversible deformation and fracture, and in liquids cause the onset of cavitation. Both solids and liquids have free surfaces, which cost some amount of free energy to form. In the case of solids, the amount of free energy to form a given unit of surface area is called surface energy, whereas for liquids the same quantity is called surface tension. In response to surface tension, the ability of liquids to flow results in behaviour differing from that of solids, though at equilibrium both tend to minimise their surface energy: liquids tend to form rounded droplets, whereas pure solids tend to form crystals.
Sources: en.wikipedia.org
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.
Rodent studies found dose-dependent tumors in several organs. The sponsor discontinued the program over cancer concerns. Human risk from long-term use remains unknown.
Controlled human endurance trials are lacking. Animal studies show increased exercise capacity under some conditions. Anecdotal reports are not equivalent to clinical evidence.
Legal status varies by country. It is not approved as a medicine, and it is prohibited in sport. Some jurisdictions restrict import, sale, or possession.