A practical reference on Nuclear receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
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.
| 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. |
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.
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.
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.
Some bats prey on other vertebrates, such as fish, frogs, lizards, birds and mammals. The fringe-lipped bat (Trachops cirrhosus), for example, is skilled at catching frogs, locating them by tracking their mating calls. The greater noctule bat (Nyctalus lasiopterus) hunts and catches birds in flight. Some species, like the greater bulldog bat (Noctilio leporinus), hunt fish, flying over the water and grabbing them with their clawed feet. They use echolocation and may be alerted by ripples on the surface or a jumping fish. Some species feed on other bats, including the spectral bat (Vampyrum spectrum) and the ghost bat (Macroderma gigas).
== History == The use of iboga in African spiritual ceremonies was first reported by French and Belgian explorers in the 19th century, beginning with the work of French naval physician and explorer of Gabon Marie-Théophile Griffon du Bellay. The first botanical description of the Tabernanthe iboga plant was made in 1889. Ibogaine was first isolated from T. iboga in 1901 by Dybowski and Landrin and independently by Haller and Heckel in the same year using T. iboga samples from Gabon. Complete synthesis of ibogaine was accomplished by G. Büchi in 1966. Since then, several other synthesis methods have been developed. Use of low doses of ibogaine (e.g. 10–30 mg/day) as a stimulant and "anti-fatigue" drug in the treatment of conditions like "cardiac atony", neurasthenia, and convalescence was advocated by French researchers in 1905. From the 1930s to 1960s, ibogaine was sold in France as Lambarène, an extract of the Tabernanthe manii plant, and promoted as a mental and physical stimulant. It was formulated at doses of 200 mg extract containing low doses of 4 to 8 mg ibogaine per tablet. The drug enjoyed some popularity among post-World War II athletes. Lambarène was withdrawn from the market in 1966 when the sale of ibogaine-containing products became illegal in France. Another formulation was Iperton, which contained Tabernanthe iboga extract 40 mg per dose unit. In 2008, Mačiulaitis and colleagues stated that in the late 1960s, the World Health Assembly classified ibogaine as a "substance likely to cause dependency or endanger human health". The U.S.
== Production == Yeast extracts in general are produced in three steps: fermentation (growing the yeast), disruption (breaking of the cells), and separation (to keep the soluble part). Although the vast majority of yeast extract spreads are made using von Liebig's traditional approach of heat-autolysis using surplus yeast from beer brewing, other methods do exist for producing specialized types. In terms of fermentation, spent beer yeast is commonly contaminated with the bitter compounds from hops, requiring a "debittering" step to wash out most of this undesired flavor. Yeast from other sources are not affected by this issue. Spent brewer's yeast is also quite biodiverse, containing yeasts other than traditional Saccharomyces cerevisiae and sometimes beer spoilage-causing lactic acid bacteria too. For disruption of the cell, some physical and chemical methods may be used in place of the heat-autolysis process. Doing so may allow specific compounds to be extracted or to produce an extract without the hydrolysis of cell contents (as in autolysis) happening. Autolysis can be assisted with added enzymes; for example, additional nuclease would enhance the release of nucleosides from RNA. Separation removes insoluble parts, mainly the yeast's cell wall, from the extract. Cell wall can be separated into two commercially useful parts: the glucans as "yeast β-glucan" and the mannans further processed into mannan-oligosaccharide (MOS). The product is finally concentrated by drying, into a thick paste or a dry powder.
On 16 May 2023, three weeks after Tangaraju was put to death, 36-year-old Muhammad Faizal Mohd Shariff, a Singaporean who was found guilty in 2019 of trafficking 1.5 kg of marijuana was reported to have lost his final appeal to commute his sentence. A day after losing his appeal, Muhammad Faizal was hanged at dawn on 17 May 2023, with the authorities confirming his execution despite not naming Muhammad Faizal out of consideration for his family's need for privacy. Two executions of a 56-year-old man and 45-year-old woman (both convicted of drug offences) were scheduled to take place on 26 July and 28 July 2023 respectively; the female offender Saridewi Djamani was believed to be the first woman to be executed in 19 years, as the last known execution of a woman took place on 19 March 2004, when 37-year-old Yen May Woen was put to death for diamorphine trafficking. The 56-year-old male drug offender Mohd Aziz Hussain, as well as Saridewi, were both hanged as scheduled, becoming the third and fourth persons respectively to be executed in Singapore in the year of 2023. On 3 August 2023, Singapore carried out the hanging of Mohamed Shalleh Abdul Latiff, a 39-year-old Singaporean and former delivery driver found guilty of trafficking 54.04g of diamorphine in 2016. In total, five executions, all once again for drug trafficking, took place in the year 2023. When 35-year-old Ahmed Salim was hanged on 28 February 2024 for murdering his former fiancée, he was the first criminal hanged in Singapore in that year.
Sources: en.wikipedia.org
=== Pests === Common herbarium pests include: silverfish, book lice (psocids), cigarette or tobacco beetles (Lasioderma), dermestids, drugstore beetles (Stegobium paniceum) A reoccurring threat to the longevity of herbarium specimens is insects, a number of which find dried plants palatable. Historically, various methods have been used to kill insects, which either come in with the plants when they are collected or are in the building where the plants are stored. Pests are commonly treated with two different methods:
=== Pray Codex === An image in the medieval manuscript of the Pray Codex (c. 1192–1195) has generated a debate among some believers since 1978. Although the Pray Codex predates the Shroud of Turin, some of the assumed features of the drawing, including the four L-shaped holes on the coffin lid, have pointed some people towards a possible attempted representation of the linen cloth. However the image on the Pray Codex has crosses on what may be one side of the supposed shroud, an interlocking step pyramid pattern on the other, and no image of Jesus. Critics point out that it may not be a shroud at all, but rather a rectangular tombstone, as seen on other sacred images. A crumpled cloth can be seen discarded on the coffin, and the text of the codex fails to mention any miraculous image on the codex shroud.
== In film and popular culture == The 1987 comedy Spaceballs features a character named Pizza the Hutt, which is a parody of Jabba the Hutt made to sound like Pizza Hutt. In the 1989 film Back to the Future Part II, Marty McFly and his family eat a "rehydrated" Pizza Hut pizza in the futuristic 2015. The 1992 film Wayne's World features a scene where Wayne, played by Mike Myers, tells the audience that he will not be bought by corporate sponsors while eating a slice of Pizza Hut pizza. There is a scene set in a Pizza Hut in the 2011 romantic comedy Just Go With It. In the 2014 Teenage Mutant Ninja Turtles film, pizza boxes from Pizza Hut are prominently displayed in the group's sewer lair. The film Slice of Life: The American Dream. In Former Pizza Huts, directed by Matthew Salleh and released in 2024, is a documentary about people who have converted former Pizza Hut buildings across America into a variety of new enterprises.
==== List of regions ==== Sometimes, overlaps and transition areas happen between the various regions of Lower Saxony. Several of the regions listed here are part of other, larger regions, that are also included in the list.
ATC code A10 Drugs used in diabetes is a therapeutic subgroup of the Anatomical Therapeutic Chemical Classification System, a system of alphanumeric codes developed by the World Health Organization (WHO) for the classification of drugs and other medical products. Subgroup A10 is part of the anatomical group A Alimentary tract and metabolism. Codes for veterinary use (ATCvet codes) can be created by placing the letter Q in front of the human ATC code: for example, QA10. National versions of the ATC classification may include additional codes not present in this list, which follows the WHO version. A10AB01 Insulin (human) A10AB02 Insulin (beef) A10AB03 Insulin (pork) A10AB04 Insulin lispro A10AB05 Insulin aspart A10AB06 Insulin glulisine A10AB30 Combinations === A10AC Insulins and analogues for injection, intermediate-acting === A10AC01 Insulin (human) A10AC02 Insulin (beef) A10AC03 Insulin (pork) A10AC04 Insulin lispro A10AC30 Combinations
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.
Rodent studies reported increased endurance and fat oxidation after GW501516 exposure. Long-term studies also found higher rates of some tumors, which led to halted development.