Research Use Only. The information presented here is for scientific and educational purposes. These compounds are not intended for human consumption, self-administration, or therapeutic use.
Introduction
AOD-9604 (also written AOD9604) is a synthetic peptide derived from the C-terminal region of human growth hormone (hGH), specifically the segment spanning residues 176-191. In preclinical and in-vitro research it is studied as a molecular tool for probing the lipolytic (fat-metabolizing) domain of the growth hormone molecule, separate from the receptor interactions that drive somatic growth. This article summarizes how the hGH fragment 176-191 is characterized in the laboratory and which adipose-tissue pathways investigators have examined.
Interest in this fragment stems from a longstanding observation in animal and cell-based studies: much of the fat-related activity of growth hormone appears to be concentrated in the terminal portion of the peptide chain. AOD-9604 was engineered to isolate that region. Everything discussed below reflects preclinical, in-vitro, and animal-model literature. Nothing here describes human use, dosing, or clinical outcomes. These materials are for research use only, not for human consumption. Researchers comparing candidates across the growth hormone axis often begin with the broader Rejuven8 research peptide catalog before narrowing to a specific mechanism study.
What Is AOD-9604? The hGH Fragment 176-191
Origin and structure
Human growth hormone is a 191-amino-acid protein. Decades of structure-function research indicated that its influence on lipid metabolism could be traced to a short stretch near the carboxyl terminus. AOD-9604 is a stabilized analog of that stretch: it corresponds to hGH residues 176-191 with an additional tyrosine residue added at the N-terminus to support handling and characterization. A single disulfide bond links the two cysteine residues, folding the short chain into the conformation studied in adipocyte models.
Why isolate a fragment?
Full-length hGH engages the growth hormone receptor and drives a wide range of downstream signals, including hepatic IGF-1 production and effects on glucose handling. By working with only the 176-191 region, researchers can ask a narrower question: which activities associated with growth hormone survive when the growth-promoting bulk of the molecule is removed? This makes the fragment a useful probe in mechanistic studies of fat cell biology rather than a stand-in for the intact hormone.
Molecular identity
The following values reflect commonly reported laboratory attributes and are provided for comparison only.
| Attribute | Reported value |
|---|---|
| Compound | AOD-9604 (hGH fragment 176-191 analog) |
| Class | Growth hormone C-terminal fragment (peptide) |
| Parent molecule | Human growth hormone (191 aa) |
| Sequence length | Approximately 16 amino acid residues |
| Approximate molecular weight | ~1815 g/mol (about 1.8 kDa) |
| Structural feature | N-terminal tyrosine, single disulfide bond |
| Research framing | Preclinical lipolysis and lipid-metabolism models |
Lipolysis Pathways Under Investigation
Stimulating fat breakdown, limiting fat storage
In cultured adipocytes and rodent models, the hGH fragment 176-191 has been studied for two complementary activities: promoting lipolysis (the enzymatic breakdown of stored triglycerides into free fatty acids and glycerol) and reducing lipogenesis (the synthesis and storage of new fat). Investigators typically measure glycerol release from fat cells as a readout of lipolytic activity, then compare the fragment against controls and against full-length growth hormone. These are laboratory endpoints in isolated tissue and animal systems, not statements about body composition in people.
The beta-3 adrenergic receptor question
Early hypotheses connected the fragment’s activity to the beta-3 adrenergic receptor (beta-3 AR), a signaling protein expressed on adipose tissue that participates in fat mobilization. Some rodent studies reported changes in beta-3 AR expression alongside altered fat metabolism. Later experiments using beta-3 AR knockout mice complicated that simple picture: fat-metabolism effects were still observed in animals lacking the receptor, suggesting the peptide may act through additional or parallel routes. The mechanism therefore remains an open research question rather than a settled pathway, which is part of why AOD-9604 continues to appear in metabolic-signaling investigations.
Reported independence from the IGF-1 growth axis
A recurring theme in the preclinical literature is that, unlike intact hGH, the 176-191 fragment has been reported to influence fat metabolism in animal and cell studies without producing the same increase in circulating IGF-1 or the same effect on insulin sensitivity and blood glucose. In mechanistic terms, this is the central reason the fragment is studied at all: it lets researchers examine a growth-hormone-associated metabolic effect while minimizing the growth-signaling activity that dominates the full molecule. As with every point here, these observations belong to laboratory and animal research and do not describe human physiology or results.
How AOD-9604 Sits Within the GH Axis Toolkit
AOD-9604 is frequently discussed alongside other peptides that act on the growth hormone axis, though the mechanisms differ substantially. Growth hormone secretagogues and releasing-hormone analogs act upstream, influencing the pituitary’s output of growth hormone, whereas the 176-191 fragment is studied as a downstream, adipose-directed probe. The table below sketches those distinctions; the values reflect commonly reported laboratory attributes and are provided for comparison only.
| Peptide | Class | Approx. MW | Primary research framing |
|---|---|---|---|
| AOD-9604 | hGH C-terminal fragment analog | ~1.8 kDa | Adipocyte lipolysis and lipid-metabolism models |
| Tesamorelin | GHRH analog | ~5.1 kDa | GHRH receptor and GH secretion research |
| CJC-1295 | GHRH analog | ~3.6 kDa | GH pulse and half-life extension studies |
| Ipamorelin | Ghrelin-receptor agonist (GHRP) | ~0.7 kDa | Selective GH secretagogue research |
The contrast is instructive. Releasing-hormone and secretagogue peptides, such as the widely referenced CJC-1295 and Ipamorelin combination, are studied for how they modulate the timing and amplitude of growth hormone release. AOD-9604, by contrast, is examined for activity localized to fat tissue and is not thought to raise systemic growth hormone in the same way. Grouping them together clarifies that “GH axis” spans several distinct molecular targets rather than a single pathway.
Research Handling and Laboratory Context
Form and reconstitution
AOD-9604 is typically supplied as a lyophilized (freeze-dried) powder, with a 5 mg vial being a common research presentation. For studies requiring a solution, the powder is reconstituted with a suitable diluent such as bacteriostatic water; the general procedure and a worked concentration example are covered in the dedicated bacteriostatic water reconstitution guide rather than repeated here. As a short peptide, reconstituted material is generally kept refrigerated and protected from repeated freeze-thaw cycles to preserve integrity for analysis.
Purity and documentation
Because mechanistic conclusions depend on the identity and purity of the material used, verifying a certificate of analysis is a routine part of responsible sourcing. Learning to read those documents, covered in the peptide COA and purity primer, helps researchers confirm that a sample matches the expected molecular weight and contains the stated compound before any experiment begins.
Frequently Asked Questions
What is AOD-9604 and how is it related to hGH?
AOD-9604 is a synthetic analog of the hGH fragment spanning residues 176-191, the C-terminal region of human growth hormone, with an added N-terminal tyrosine. It is studied in preclinical research as a way to isolate the fat-metabolism-associated portion of the growth hormone molecule from its growth-signaling activity.
How does AOD-9604 work in lipolysis research?
In cultured fat cells and animal models, the fragment is examined for its ability to promote lipolysis (the breakdown of stored fat) and reduce lipogenesis (the storage of new fat). Investigators often measure glycerol release as a marker of lipolytic activity. The precise receptor pathway, including the role of the beta-3 adrenergic receptor, remains an open question in the literature.
Does AOD-9604 affect IGF-1 or blood glucose in studies?
Preclinical reports describe the 176-191 fragment as influencing fat metabolism in animal and cell systems without producing the same rise in circulating IGF-1 or the same effect on insulin sensitivity seen with full-length growth hormone. These are laboratory observations and do not describe outcomes in humans.
What is the molecular weight of AOD-9604?
AOD-9604 has a commonly reported molecular weight of approximately 1815 g/mol, roughly 1.8 kDa, with a sequence of about 16 amino acid residues and a single disulfide bond. Confirming these attributes against a certificate of analysis is standard practice before laboratory work.
How is AOD-9604 different from CJC-1295 or Ipamorelin?
CJC-1295 and Ipamorelin act upstream on the growth hormone axis, studied for how they influence the pituitary’s release of growth hormone. AOD-9604 is a downstream fragment studied for activity localized to adipose tissue and is not thought to raise systemic growth hormone the way secretagogues do.
Is AOD-9604 approved for human use?
No. AOD-9604 is discussed here strictly as a research compound. It is for research use only, not for human consumption, and the material in this article reflects preclinical, in-vitro, and animal studies rather than approved human applications.
References and Further Reading
- Heffernan and colleagues, studies of the hGH lipolytic fragment AOD9604 and lipid metabolism in obese and beta-3 adrenergic receptor knockout mice. PubMed: AOD9604 lipolysis
- Ng and colleagues, metabolic effects of the C-terminal fragment of human growth hormone. PubMed: growth hormone fragment 176-191
- Research on growth hormone and lipolysis in adipose tissue. PubMed: growth hormone lipolysis adipocyte
- Studies of the beta-3 adrenergic receptor in fat metabolism. PubMed: beta-3 adrenergic receptor lipolysis
- Structure-function analysis of human growth hormone domains. PubMed: human growth hormone structure function
- General literature on the AOD-9604 peptide. PubMed: AOD-9604
- Reports on the hGH 177-191 lipolytic fragment. PubMed: hGH fragment 177-191
