# How does AOD-9604 work? What rat and mouse studies measured Updated 2026-10-16. Most of what is known about how AOD-9604 works comes from three Monash University papers published in 2000 and 2001. In obese rats and mice, treated animals showed more fat breakdown and more fat burning. In a cell test, AOD-9604 did not bind the growth hormone receptor. These are animal and lab results. How AOD-9604 works in people has not been established in the sources read. | | | | --- | --- | | Compound | AOD-9604, a 16-amino-acid peptide based on the tail end of human growth hormone | | Rat study | Obese Zucker rats treated daily for 19 days (Ng et al., Hormone Research, 2000) | | Mouse study, body weight and fuel use | Obese ob/ob and lean mice treated for 14 days (Heffernan et al., International Journal of Obesity, 2001) | | Mouse study, beta-3 receptor | Obese mice and beta-3 knock-out mice (Heffernan et al., Endocrinology, 2001) | | Growth hormone receptor binding | None found in a cell assay (Heffernan et al., 2001) | | Mechanism in people | Not established in the sources read (16 October 2026) | | Published human half-life | Not established in the sources read (16 October 2026) | Between meals, your fat cells slowly let stored fuel out into your blood. Hormones set how fast that happens. AOD-9604 was built from one end of growth hormone, one of those hormones. The early studies asked a simple question: can that small piece change how fat cells behave on its own? This page is part of [the AOD-9604 hub](/learn/aod-9604). Every result below comes from rats, mice or cells, and each one comes with its limit. New to the compound? Start with [what AOD-9604 is](/learn/aod-9604/what-is-aod-9604). The human obesity trial is on [the study findings page](/learn/aod-9604/aod-9604-study-findings). ## How does AOD-9604 work in the body? How AOD-9604 works in the human body has not been established in the sources read. The clues come from animals. In obese Zucker rats, fat tissue from treated animals showed more lipolytic activity. Lipolysis means breaking down stored fat. In obese mice treated for 14 days, two measures went up. One was fat oxidation, which means burning fat for fuel. The other was plasma glycerol, a substance in the blood that rises when fat is broken down. These are results in rodents. They do not show that the same changes happen in people. Glycerol is a useful clue. Fat cells release it when they break down stored fat, so more glycerol in the blood points to more breakdown. It does not tell you how much fat a body lost. The mouse study also tracked body weight. Treated obese mice gained less weight than untreated ones. That is a mouse finding, and it does not show a weight effect in people. ## Does AOD-9604 act through the growth hormone receptor? No, going by a 2001 cell test. Researchers used cells built to carry the human growth hormone receptor. A receptor is like a lock on a cell, and a hormone is the key that fits it. The team checked two things: whether AOD-9604 competed with growth hormone for the lock, and whether it made the cells multiply. AOD-9604 did neither. Growth hormone did both. The authors concluded that AOD-9604 does not interact with the growth hormone receptor. This was a test on cells in a dish. It does not describe what happens in a person. That result raises an obvious question. If AOD-9604 comes from growth hormone but does not use its receptor, what does it use instead? The paper does not answer that. The beta-3 experiments in the next section were the authors' attempt to find out. [What AOD-9604 is](/learn/aod-9604/what-is-aod-9604) sets out how the fragment differs from the whole hormone. ![Two receptors on a cell surface, each labelled Receptor: one holds a large shape labelled Whole hormone, the other stays empty beside a small chain labelled Short fragment.](/assets/content/edu-receptor-lock-and-key.png) In a 2001 cell test, growth hormone bound its receptor and made the cells multiply; AOD-9604 did not compete for the receptor and did not make the cells multiply. Source: Heffernan et al., International Journal of Obesity, 2001. ## What did the beta-3 adrenergic receptor experiments find? The beta-3 adrenergic receptor is another docking spot on fat cells, linked to fat breakdown. A 2001 mouse study tested its role. In obese mice treated for 14 days, AOD-9604 raised beta-3 receptor RNA back to the level seen in lean mice. RNA is the message a cell reads to build the receptor. Next, the team used mice bred without the beta-3 receptor. In those mice, long-term treatment did not change body weight and fat breakdown the way it did in normal mice. Yet a short, one-off test still raised energy use and fat burning. So the authors concluded the effects do not run directly through this receptor. This result has layers, and it shows why one experiment rarely settles how something works. The receptor level went up. The long-term effect needed the receptor. The short-term effect did not. The authors suggested that the higher receptor level may add to fat cells becoming more sensitive to signals to break down fat. All of this was seen in mice, and it does not show the same pathway in people. ## Does AOD-9604 change blood sugar, insulin or IGF-1? The animal studies report on blood sugar and insulin, but their summaries say nothing about IGF-1. In obese Zucker rats treated daily for 19 days, AOD-9604 did not harm insulin sensitivity, which is how well the body responds to insulin. The team measured it with a euglycemic clamp, a test that holds blood sugar steady while it records that response. Whole growth hormone did harm insulin sensitivity. In obese mice, AOD-9604 did not cause high blood sugar or lower insulin release, but growth hormone did. IGF-1, a growth signal made mainly in the liver, was not reported in the summaries read. There are some human measurements too. A 2013 paper by Stier and colleagues summed up blood sugar, insulin and IGF-1 readings from the human trials. The paper has ties to the company that ran the trials, and it does not show safety for other groups of people or other products. [The side-effects page](/learn/aod-9604/aod-9604-side-effects) covers the safety record. ## What happens to AOD-9604 in the body? How long AOD-9604 stays in the human body is an open question. No human half-life was established in the sources read. A half-life is the time it takes for the measured level of a substance to fall by half. One lab study mixed AOD-9604 with serum, the liquid part of blood, and with urine in a dish. It found six possible metabolites, the smaller pieces left after enzymes cut the peptide up. One piece, made of the amino acids CRSVEGSCG, was significantly more stable than the other pieces or the whole peptide. That work was done in a dish. It describes chemistry, not time in a living person. The team built this study for anti-doping labs, which test athletes for banned substances. They wrote that screening for the stable piece may allow a longer window of detection. That is a testing goal, not a finding about safety or effects. [Do peptides show up on drug tests](/learn/peptide-science/do-peptides-show-up-on-drug-tests) explains how this kind of screening works in general. ## Comparison What each of the three early papers measured for AOD-9604, and what it cannot show. The table records measurements and limits and does not rank the papers. | Paper | Animals or cells | What was measured | What it cannot show | | --- | --- | --- | --- | | Ng et al., Hormone Research, 2000 | Obese Zucker rats, 19 days | Weight gain and fat breakdown in fat tissue; insulin sensitivity by euglycemic clamp | That the same changes happen in people | | Heffernan et al., International Journal of Obesity, 2001 | Obese ob/ob and lean mice, 14 days; cells carrying the human growth hormone receptor | Weight gain, fat burning, blood glycerol, blood sugar and insulin; receptor binding and cell growth | That a cell result holds in a whole body, or that mouse results hold in people | | Heffernan et al., Endocrinology, 2001 | Obese mice and mice bred without the beta-3 receptor | Beta-3 receptor RNA, body weight and fat breakdown in long-term and one-off tests | That the beta-3 pathway works the same way in people | ## Frequently asked questions ### Is AOD-9604 a fat burner? AOD-9604 is a synthetic peptide. In obese mice, treatment went with more fat burning and more glycerol in the blood. That is a mouse measurement. The human obesity trial announced on 21 February 2007 did not reach statistical significance on weight loss compared with placebo, a dummy tablet. ### Does AOD-9604 bind the growth hormone receptor? A 2001 cell test found that AOD-9604 did not compete with growth hormone for the human growth hormone receptor. It also did not make the cells multiply through that receptor. ### What is lipolysis? Lipolysis is the breakdown of stored fat in fat cells into glycerol and fatty acids, which the body can use as fuel. The AOD-9604 mouse study used a rise in blood glycerol as a sign of lipolysis. ## Citations - Stier H, Vos E, Kenley D.. Journal of Endocrinology and Metabolism. 2013;3(1-2):7-15. DOI: 10.4021/jem157w - Ng FM, Sun J, Sharma L, et al.. Hormone Research. 2000;53(6):274-278. DOI: 10.1159/000053183 - Heffernan MA, Thorburn AW, Fam B, et al.. International Journal of Obesity. 2001;25(10):1442-1449. DOI: 10.1038/sj.ijo.0801740 - Heffernan M, Summers RJ, Thorburn A, et al.. Endocrinology. 2001;142(12):5182-5189. DOI: 10.1210/endo.142.12.8522 - Cox HD, Smeal SJ, Hughes CM, Cox JE, Eichner D.. Drug Testing and Analysis. 2015;7(1):31-38. DOI: 10.1002/dta.1715 --- Canonical page: https://www.formlaboratories.com/learn/aod-9604/how-aod-9604-works Form Laboratories - Perth-based research-use-only peptide supplier, shipping Australia-wide. - Site guide for agents: https://www.formlaboratories.com/llms.txt - Sitemap: https://www.formlaboratories.com/sitemap.xml - Full catalogue: https://www.formlaboratories.com/shop - Contact: hello@formlaboratories.com All materials are supplied for laboratory research use only - not for human or veterinary use, and nothing on this site is medical advice.