What are growth hormone secretagogues?
Growth hormone secretagogues are compounds that stimulate the secretion of endogenous growth hormone in research models. The category includes growth hormone-releasing hormone (GHRH) analogs such as CJC-1295 and growth hormone-releasing peptides (GHRPs) such as ipamorelin, GHRP-6, GHRP-2, and hexarelin. In published in-vitro and animal studies, these molecules act on pituitary somatotroph cells to influence GH release rather than supplying GH directly. They are studied as research tools for examining the GH axis and are supplied strictly for laboratory use, not for human or animal consumption.
What is the difference between a GHRH analog and a GHRP?
The two classes act on different receptors in research models. A GHRH analog such as CJC-1295 binds the growth hormone-releasing hormone receptor on pituitary somatotrophs, mimicking the body's natural GHRH signal. A GHRP such as ipamorelin or GHRP-6 binds the growth hormone secretagogue receptor (GHS-R1a), the same receptor associated with ghrelin signaling. Because the two classes engage distinct receptors, laboratory studies often examine them separately and in combination to characterize their independent and additive effects on measured GH output.
What does CJC-1295 do in research models?
CJC-1295 is a synthetic GHRH analog studied for its ability to stimulate growth hormone release from pituitary cells in laboratory models. As a modified fragment of natural GHRH, it binds the GHRH receptor and, in published animal and in-vitro work, is associated with increased measured GH and downstream IGF-1 in those systems. Researchers study it to investigate GHRH receptor pharmacology and the dynamics of the GH axis. It is a research chemical supplied for in-vitro and laboratory study only and is not approved for therapeutic use.
What is the DAC modification on CJC-1295?
DAC stands for Drug Affinity Complex, a modification that extends the circulating half-life of CJC-1295 in research models. The DAC version incorporates a chemical group that binds serum albumin, which in published studies slows clearance and prolongs the molecule's presence compared with the non-DAC form. The non-DAC variant, sometimes labeled modified GRF (1-29), clears more rapidly. Laboratories select between the two forms depending on whether a study design calls for sustained or short-acting GHRH receptor activity. Both are research-use-only materials.
What is ipamorelin and why is it called selective?
Ipamorelin is a pentapeptide GHRP that binds the growth hormone secretagogue receptor (GHS-R1a) in research models. It is described as selective because, in published studies, it stimulates measured growth hormone release with relatively little effect on other pituitary hormones such as cortisol and prolactin, compared with earlier secretagogues like GHRP-6. This selectivity profile makes it a frequent subject in laboratory work isolating GHS-R-mediated GH effects. Ipamorelin is supplied as a research chemical for in-vitro and laboratory use only, not for consumption.
How does GHRP-6 differ from ipamorelin?
GHRP-6 and ipamorelin both bind the GHS-R1a receptor, but they differ in selectivity in research models. GHRP-6 is one of the earlier growth hormone-releasing peptides and, in published studies, is associated with a marked increase in appetite signaling and a broader effect on cortisol and prolactin. Ipamorelin, a later pentapeptide, shows a cleaner profile with less off-target hormone activity in laboratory data. Researchers may select GHRP-6 specifically when studying ghrelin-receptor-linked appetite pathways. Both are research-use-only compounds.
What is the rationale for studying CJC-1295 with ipamorelin together?
The pairing is studied because the two compounds act through different receptors and, in research models, can produce additive or synergistic GH release. CJC-1295 engages the GHRH receptor while ipamorelin engages the GHS-R1a receptor, so combining them in laboratory studies allows investigators to examine dual-pathway stimulation of the same somatotroph cells. Published work explores whether co-administration in animal models yields a larger measured GH pulse than either alone. This combination is examined as a research model only and is not a product for human or animal use.
What is IGF-1 LR3 and how does it differ from the secretagogues?
IGF-1 LR3 (Long R3 IGF-1) is a modified analog of insulin-like growth factor 1, a hormone that acts downstream of growth hormone in research models. Unlike the secretagogues, which prompt the pituitary to release GH, IGF-1 LR3 acts directly on IGF-1 receptors and bypasses the pituitary entirely. The LR3 modification reduces binding to IGF-binding proteins, extending its activity in laboratory studies. Researchers use it to study IGF-1 receptor signaling independent of the GH-release step. It is a research-use-only material, not for consumption.
What is the GH axis?
The GH axis is the regulatory loop that controls growth hormone in research models. In the hypothalamus, GHRH stimulates and somatostatin inhibits the pituitary's release of growth hormone. Circulating GH then acts on peripheral tissues, notably the liver, prompting production of IGF-1, which mediates many downstream effects and feeds back to dampen further GH release. Growth hormone secretagogues are studied as tools that act at different points in this axis, which is why their measured effects on GH and IGF-1 are a frequent subject of laboratory investigation.
What is the role of somatostatin?
Somatostatin is the inhibitory signal in the GH axis, acting as a counterweight to GHRH in research models. Released from the hypothalamus, it suppresses growth hormone secretion from the pituitary, and the interplay between rising GHRH and falling somatostatin is thought to shape the pulsatile pattern of GH release observed in animal studies. Researchers studying secretagogues consider somatostatin tone because it can blunt or modulate the measured GH response to a GHRH analog or GHRP in laboratory systems. It is a core variable in GH axis research.
Are these peptides FDA approved?
No. CJC-1295, ipamorelin, GHRP-6, GHRP-2, hexarelin, and IGF-1 LR3 are not approved by the FDA for therapeutic use and are not approved drugs. They are supplied as research chemicals for laboratory and in-vitro study only. They have not been evaluated by the FDA for safety or efficacy in humans or animals, and they are not intended to diagnose, treat, cure, or prevent any condition. Any handling should follow appropriate laboratory safety practices, and these materials are not for human or animal consumption.
How are they reconstituted and stored for research?
In published laboratory protocols, lyophilized peptides such as these are typically reconstituted with bacteriostatic or sterile water and kept cold. General research practice stores lyophilized powder frozen and protected from light, with reconstituted solution refrigerated and used within a limited window to preserve stability. Specific volumes and concentrations depend on the study design and the documentation supplied with the material. This is a general description of laboratory handling for research use only, not instructions for any form of administration or consumption.
Why is pulsatile signaling important?
Pulsatile signaling matters because growth hormone in research models is released in discrete bursts rather than at a constant level. Animal studies indicate that the pattern of GH pulses, shaped by the alternating influence of GHRH and somatostatin, can affect downstream measurements differently than steady exposure would. Because secretagogues can alter the timing and amplitude of these pulses, researchers studying the GH axis often examine pulsatility rather than total output alone. It is a key consideration when interpreting laboratory data on GH-releasing compounds.
What is MK-677 / ibutamoren?
MK-677, also called ibutamoren, is a non-peptide growth hormone secretagogue studied in research models. Unlike the injectable peptides, it is an orally active small molecule that binds the same GHS-R1a receptor as the GHRPs, and in published studies it is associated with sustained stimulation of measured GH and IGF-1. Because it is not a peptide, it is sometimes grouped separately from compounds like ipamorelin. MK-677 is a research-use-only material, is not FDA approved, and is not intended for human or animal consumption.
Are these for human use?
No. None of the compounds described on this page are for human use, animal use, or consumption of any kind. They are sold strictly as research chemicals for laboratory and in-vitro study by qualified investigators. They are not approved drugs or supplements, have not been evaluated for safety in humans, and must not be ingested, injected, or otherwise administered to people or animals. Purchasers are responsible for handling these materials in compliance with applicable laws and appropriate laboratory safety standards.
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