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.
Last reviewed on 2025-10-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
At the molecular level, GW501516 binds and activates PPARδ, a nuclear receptor that regulates transcription. Activation shifts expression of genes involved in fatty acid oxidation, energy expenditure, and lipid transport in skeletal muscle and liver. Animal studies report increased endurance and altered lipid profiles after exposure. Human data are limited to small trials and do not establish long-term safety or efficacy. PPARδ also has roles in cell proliferation, so the relationship between activation and cancer risk remains an open question.
Published literature on cardarine includes in vitro assays, rodent experiments, and a small number of human studies. Reports describe effects on exercise capacity and lipid metabolism in animals, while human evidence is sparse. Many online descriptions present the compound as a proven endurance aid, a claim not supported by regulatory approval or large clinical trials. Analytical studies focus on identifying the parent compound and its metabolites in biological samples. Important uncertainties include species differences, dose-response relationships, and the relevance of rodent tumor findings to humans.
Cardarine is the common name for GW501516, a synthetic compound studied as a peroxisome proliferator-activated receptor delta agonist. Researchers developed it to explore treatments for lipid disorders and metabolic conditions. It is not an approved medicine in any country. Early clinical work examined changes in HDL cholesterol and triglycerides, but development was discontinued after animal studies raised concerns about cancer. The compound remains available as a research chemical and appears in discussions of performance enhancement.
A common misconception is that cardarine has been proven safe for human use. In reality, human clinical data are limited, and long-term animal studies have raised concerns about cancer. Another misconception is that it is a supplement or vitamin-like compound. It is a synthetic research chemical with no approved medical indication. Scientific discussion often focuses on its mechanism and detection rather than therapeutic use. Regulatory and anti-doping literature treats it primarily as a prohibited substance.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Cardarine | Also called GW501516 and endurobol. |
| Chemical formula | C21H18F3NO3S2 | Molecular weight about 453.5 g/mol. |
| Appearance | White to off-white solid | Form depends on synthesis and purity. |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water. |
| Typical storage | -20 °C, desiccated, protected from light | Common for research chemicals. |
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.
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.
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 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.
In the fitness and bodybuilding literature, cardarine is frequently discussed as an endurance agent or fat-loss compound, although such claims are not supported by robust clinical evidence. Online descriptions often mix animal data, user anecdotes, and marketing language. Researchers who study PPARδ agonists distinguish between receptor activation in controlled experiments and unsupervised use of unverified products. The latter introduces unknown purity, dose, and interactions, making reported experiences difficult to interpret scientifically.
GW501516 acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in transcription of genes related to lipid handling and energy use. Activation of PPARδ can shift skeletal muscle toward greater fatty acid oxidation in animal models, which is one reason it drew interest for metabolic disease and exercise research. The exact downstream effects depend on tissue, species, dose, and duration. Human data are sparse, so many proposed benefits remain hypotheses rather than established clinical outcomes.
The C-terminal domain of ADP-ribose diphosphatase contains the Nudix sequence, a highly conserved amino acid sequence that is found in over 450 putative proteins in about 90 different species. A part of this sequence known as the Nudix fold is the catalytic part of the sequence. It is a structurally conserved loop-helix-loop motif that creates a scaffold for metal binding and pyrophosphatase chemistry in the enzyme. ADP-ribose hydrolases in general act as protective agents against excessive intracellular accumulation of ADP-ribose, as high intracellular levels of ADP-ribose can be damaging to the cell. ADP-ribose diphosphatase, in particular, hydrolyzes ADP-ribose into AMP and D-ribose 5-phosphate, both of which are intermediates of central metabolic pathways and therefore are easily reused. Other common names for ADP-ribose diphosphatase include ADP-ribose pyrophosphatase and ADPRase. ADP-ribose is commonly referred to as ADPR.
By 1951, Alec Todd and collaborators at the University of Cambridge had determined by biochemical methods how the backbone of DNA is structured via the successive linking of carbon atoms 3 and 5 of the sugar to phosphates. This would help to corroborate Watson and Crick's later X-ray structural work. Todd would later be awarded the 1957 Nobel Prize in Chemistry for this and other discoveries related to DNA. Late in 1951, Francis Crick started working with James Watson at the Cavendish Laboratory within the University of Cambridge. DNA's role in heredity was confirmed in 1952 when Alfred Hershey and Martha Chase in the Hershey–Chase experiment showed that DNA is the genetic material of the enterobacteria phage T2.
Agarose gel electrophoresis is a technique widely used to estimate the size of nucleic acid fragments and identify them based on their differential mobility in the gel. Nucleic acids are commonly stained and detected using either ethidium bromide or SYBR Green dyes. The most common electrophoretic stain in agarose gel is ethidium bromide, however, SYBR green presents greater resolution and yield for single-stranded nucleic acid detection. The dyes grant fluorescence to DNA and RNA under 300 nm UV light. This occurs due to their intercalating nature. In double helical nucleic acids, the dyes bind between two strands, and in single-stranded nucleic acids, the dyes bind short, duplex segments formed within a strand.
Diphtheria toxin is produced by virulent Corynebacterium diphtheriae that infect the mucosal membranes of the throat and nasal cavity causing a gray, thickened lining of the throat, sore throat, weakness, mild fever, swollen glands of the neck, and difficulty breathing. Diphtheria toxin is an ADP-ribosyltransferase that inhibits protein synthesis which causes the symptoms associated with the disease. Diphtheria used to be a leading cause of childhood death until the creation of a vaccine. The diphtheria vaccine contains a diphtheria toxoid, antigenically identical yet inactivated and non-toxic. When the toxoid is introduced to the body in a vaccine, an immune response is mounted without sequelae associated with the toxigenicity.
Naturally occurring samarium (62Sm) is composed of five stable isotopes, 144Sm, 149Sm, 150Sm, 152Sm and 154Sm, and two extremely long-lived radioisotopes, 147Sm (half life: 1.066×1011 y) and 148Sm (6.3×1015 y), with 152Sm being the most abundant (26.75% natural abundance). 146Sm (9.20×107 y) is also fairly long-lived, but is not long-lived enough to have survived in significant quantities from the formation of the Solar System on Earth, although it remains useful in radiometric dating in the Solar System as an extinct radionuclide. It is the longest-lived nuclide that has not yet been confirmed to be primordial. Its instability is due to having 84 neutrons (two more than 82, which is a magic number corresponding to a stable neutron configuration), and so it may emit an alpha particle (which has 2 neutrons) to form neodymium-142 with 82 neutrons. Other than those, the longest-lived radioisotopes are 151Sm, which has a half-life of 94.6 years, and 145Sm, which has a half-life of 340 days. All of the remaining radioisotopes, which range from 129Sm to 168Sm, have half-lives that are less than two days, and the majority of these have half-lives that are less than 48 seconds. The most stable of the known isomers is 141mSm (half-life 22.6 minutes). The long-lived isotopes, 146Sm, 147Sm, and 148Sm, decay by alpha emission to isotopes of neodymium. Lighter unstable isotopes of samarium primarily decay by electron capture to isotopes of promethium, while heavier ones decay by beta decay to isotopes of europium.
Sources: en.wikipedia.org
The study found an overall 1.4 fold increase in risk of cardiovascular ischemic events relative to the control arms. The results were heterogenous, with clear evidence of increased risk relative to placebo but not relative to other diabetes treatments and higher risk associated with combinations of rosiglitazone with insulin or metformin. Based on the 1.4 fold increased risk relative to control groups, FDA scientist David Graham presented an analysis suggesting that rosiglitazone had caused 83,000 excess heart attacks between 1999 and 2007. The advisory panel voted 20 : 3 that the evidence available indicated that rosiglitazone increased the risk of cardiovascular events and 22 : 1 that the overall risk:benefit ratio of rosiglitazone justified its continued marketing in the United States. The FDA placed restrictions on the drug, including adding a boxed warning about heart attacks, but did not withdraw it. In 2000 a study to address the concerns regarding cardiovascular safety was requested by the European Medicines Agency (EMA). GSK agreed to perform post-marketing a long-term cardiovascular morbidity/mortality study in patients on rosiglitazone in combination with a sulfonylurea or metformin: the RECORD study. The results as published in 2009 showed that rosiglitazone was non-inferior to treatment with metformin or a sulfonylurea with respect to the rate of cardiovascular events and cardiovascular death. European regulators concluded that due in part to design limitations, the results neither proved nor eliminated concerns of excess cardiovascular risk.
In January 2018, Thaçi said that Kosovo would have supported U.S. president Donald Trump's decision to relocate the U.S. embassy from Tel Aviv to Jerusalem, which would have made it the only Muslim-majority nation to do so. Thaçi told Express that if his country was given full United Nations membership, it would vote "all the time" with the U.S., even on the resolution motioned last month to protest Trump's decision. Thaçi met with Trump on the sidelines of the United Nations General Assembly in September 2017 in New York, inviting him to visit Pristina, the capital of Kosovo. According to local media, he said their meeting was "exceptionally friendly, warm." "The Head of State thanked President Trump for his personal support for Kosovo," his office said in a statement, calling the U.S. a "strategic partner" and saying the support of Washington was "crucial to the peace, stability and overall development of Kosovo and the region." Thaçi told Pristina-based broadcaster RTV21, "President Trump, like all other U.S. presidents, has a clear vision for Kosovo. It is unique support to our country. He said that Kosovo is a wonderful country and that we are a wonderful people." On 26 November 2019, an earthquake struck Albania. President Thaçi was part of a presidential delegation that visited the earthquake epicentre and expressed his condolences on behalf of Kosovo. In 2019 he met with Trump's special envoy Grenell, and in February 2020 signed an agreement with Serbia's president Vučić.
== Acquiring and manufacturing climbing gear == In the early 1950s, most American climbers imported climbing equipment from Europe or acquired it from US Army surplus. Pitons from these sources were made of mild steel that twisted and became unusable after only a few placements. Gallwas recognized the problem and was among the first to make and use heat-treated chrome-molybdenum steel alloy pitons. He patterned his pitons after John Salathé's so they could be placed hundreds of times without twisting. These improved pitons proved instrumental to the success of the first ascent of the Northwest Face of Half Dome in 1957. That same year, Yvon Chouinard began to produce and sell alloy-steel pitons. Chouinard's success with his pitons led him to establish Chouinard Equipment, Ltd, which later became Black Diamond Equipment, Ltd.
== Research and innovation == BioDuro is involved in developing data-driven and automated workflows intended to accelerate discovery timelines. The company has partnered with technology firms, including Atombeat, to integrate AI-supported peptide-design platforms with high-throughput peptide synthesis and iterative screening workflows. According to the company, these approaches are designed to reduce design–test cycles in peptide and bioconjugate programs; independent evaluation of the platform’s performance is still limited in publicly available literature.
The following year he was elected to membership at the Institute of Medicine. In 1987, he became Professor Emeritus of Medicine at Harvard Medical School. One year later he was the first Paul Klemperer Award recipient at the New York Academy of Medicine. In 1995, Gross won the Lifetime Achievement Award of The Wound Healing Society.
Sources: en.wikipedia.org
Although towards the end of the century, MacBride's theories were being challenged, the medical authorities in Britain remained committed to the notion that scurvy was a disease of internal 'putrefaction' and the Sick and Hurt Board, run by administrators, felt obliged to follow its advice. Within the Royal Navy, however, opinion – strengthened by first-hand experience with lemon juice at the siege of Gibraltar and during Admiral Rodney's expedition to the Caribbean – had become increasingly convinced of its efficacy. This was reinforced by the writings of experts like Gilbert Blane and Thomas Trotter and by the reports of up-and-coming naval commanders. With the coming of war in 1793, the need to eliminate scurvy became more urgent. The first initiative came not from the medical establishment but from the admirals. Ordered to lead an expedition against Mauritius, Rear Admiral Gardner was uninterested in the wort, malt, and elixir of vitriol that were still being issued to ships of the Royal Navy, and demanded that he be supplied with lemons, to counteract scurvy on the voyage. Members of the Sick and Hurt Board, recently augmented by two practical naval surgeons, supported the request, and the Admiralty ordered that it be done. There was, however, a last-minute change of plan, and the expedition against Mauritius was canceled. On 2 May 1794, only HMS Suffolk and two sloops under Commodore Peter Rainier sailed for the east with an outward bound convoy, but the warships were fully supplied with lemon juice and the sugar with which it had to be mixed.
==== Autonomic problems ==== Although neurogastroenterological manifestations in connective tissue disorders are common, their root cause is not yet known. Splanchnic circulation, small fiber neuropathy and altered vascular compliance have all been named as potential contributors to gastrointestinal complaints, particularly for patients who have a known, comorbid autonomic condition. Dysautonomia symptoms, autonomic system dysfunction, in hEDS is associated with exercise intolerance and cardiac atrophy.
Growth factors, stimulated by integrins and MMPs, cause cells to proliferate at the wound edges. Keratinocytes themselves also produce and secrete factors, including growth factors and basement membrane proteins, which aid both in epithelialization and in other phases of healing. Growth factors are also important for the innate immune defense of skin wounds by stimulation of the production of antimicrobial peptides and neutrophil chemotactic cytokines in keratinocytes. Keratinocytes continue migrating across the wound bed until cells from either side meet in the middle, at which point contact inhibition causes them to stop migrating. When they have finished migrating, the keratinocytes secrete the proteins that form the new basement membrane. Cells reverse the morphological changes they underwent in order to begin migrating; they reestablish desmosomes and hemidesmosomes and become anchored once again to the basement membrane. Basal cells begin to divide and differentiate in the same manner as they do in normal skin to reestablish the strata found in reepithelialized skin.
==== Hyaluronic acid ==== Hyaluronic acid (or "hyaluronan") is a polysaccharide consisting of alternating residues of D-glucuronic acid and N-acetylglucosamine, and unlike other GAGs, is not found as a proteoglycan. Hyaluronic acid in the extracellular space confers upon tissues the ability to resist compression by providing a counteracting turgor (swelling) force by absorbing significant amounts of water. Hyaluronic acid is thus found in abundance in the ECM of load-bearing joints. It is also a chief component of the interstitial gel. Hyaluronic acid is found on the inner surface of the cell membrane and is translocated out of the cell during biosynthesis. Hyaluronic acid acts as an environmental cue that regulates cell behavior during embryonic development, healing processes, inflammation, and tumor development. It interacts with a specific transmembrane receptor, CD44.
Sources: en.wikipedia.org
Cardarine is a common name for the investigational compound GW501516. It acts as a PPARδ agonist and is not approved for human use. It is prohibited in sport.
It activates PPARδ, a nuclear receptor that influences gene expression related to lipid and energy metabolism. Animal studies show changes in endurance and lipid levels. Human effects and risks are not well established.
No, cardarine is not a steroid. It belongs to a different chemical class, the PPARδ agonists. It is also not a selective androgen receptor modulator.
Yes, WADA prohibits cardarine as a PPARδ agonist. It appears on the prohibited list and can be detected in urine or blood. Athletes using it risk sanctions.