Everything below concerns Ipamorelin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-02-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue family. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues that resist enzymatic breakdown. Researchers at Novo Nordisk described the compound in the 1990s while searching for agents that release growth hormone with fewer side effects than earlier secretagogues. The molecule acts as an agonist at the ghrelin receptor, also called GHS-R1a, which is expressed in the pituitary and in several peripheral tissues.
Selectivity distinguishes ipamorelin from first-generation secretagogues such as GHRP-6. At doses that reliably raise growth hormone, it shows little stimulation of adrenocorticotropic hormone or cortisol release in animal models, and it does not markedly raise prolactin or appetite. Binding at GHS-R1a on pituitary somatotrophs triggers calcium influx and pulsatile growth hormone secretion. Because the compound mimics the natural ghrelin signal, the release pattern tends to follow the body's own rhythm rather than producing a sustained elevation.
Ipamorelin is a synthetic pentapeptide that acts on the growth hormone secretagogue receptor, also known as the ghrelin receptor. Its sequence contains five amino acid residues, including a non-natural residue that increases stability against enzymatic breakdown. The compound was developed in the 1990s as part of research into small peptides that stimulate pituitary hormone release. Unlike larger protein hormones, it can be produced by solid-phase peptide synthesis and characterized by standard analytical methods.
At the receptor level, ipamorelin binds GHS-R1a and triggers signaling through Gq-coupled pathways. Activation leads to calcium release and downstream effects in pituitary somatotroph cells. These events promote the release of growth hormone into circulation. The response depends on the presence of the receptor and on the physiological state of the animal or tissue studied. Because the receptor is also found in other tissues, effects beyond the pituitary have been examined in laboratory models, though the extent of those effects remains an area of ongoing study.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Includes two non-natural residues |
| Molecular weight | About 711.9 g/mol | Confirmed by mass spectrometry |
| Appearance | White to off-white powder | Typical lyophilized form |
| Receptor target | GHS-R1a | Ghrelin receptor agonist |
| Plasma half-life | Roughly 2 hours | Varies by species and assay |
Ipamorelin 是一种合成五肽，在 20 世纪 90 年代被报道为生长激素促分泌剂。其结构基于胃饥饿素受体激动剂的设计思路，但并非天然激素。早期药理学研究显示，它可刺激垂体释放生长激素，而对应激激素轴的影响相对较小。该化合物常被用作研究生长激素调节通路的工具分子。
在机制层面，ipamorelin 与生长激素促分泌受体 1a 型结合，该受体也介导胃饥饿素的多种效应。受体激活后，细胞内信号促进生长激素从垂体前叶释放。由于对促肾上腺皮质激素和皮质醇的刺激较弱，它被视为选择性较高的促分泌剂。这种选择性在动物模型和少量人体研究中被观察到，但人体数据仍然有限。
Research quantities of ipamorelin are typically distributed as a white to off-white lyophilized powder. The solid dissolves readily in water and in aqueous buffers, and stock solutions are commonly prepared in sterile water or a mildly acidic diluent. Adsorption to plastic and glass surfaces can reduce the concentration of very dilute solutions, so containers and transfer steps deserve attention when accurate concentrations matter. Reconstituted material is generally used promptly rather than held for extended periods.
Storage recommendations for the dry solid center on low temperature and low moisture, most often -20 °C in a sealed, desiccated container protected from light. Solutions are less stable than the powder and are usually kept cold and used within a short window. Freeze-thaw cycling is a recognized source of loss, and aliquoting before freezing is a standard precaution. These practices derive from general peptide handling principles rather than from a single published stability trial, so exact shelf lives should be treated as approximate.
Former faculty member Ernest Lyon was a United States ambassador to Liberia and the founder of the Maryland Industrial and Agricultural Institute for Colored Youths. Noted African American historian and pioneering scholar Dr. Benjamin A. Quarles served on its faculty for many decades. Physician-scientist Charles R. Drew, known for his work on blood transfusion, was Morgan College's first athletic director. African-American historian Rosalyn Terborg-Penn wrote on women's suffrage. Flora E. Strout, Morgan College teacher and principal, wrote the school's anthem. Notable faculty currently teaching at Morgan State University include bestselling author and filmmaker MK Asante, and scholar Raymond Winbush.
== Temperature regulation == In addition to their role in weight control, dynorphins have been found to regulate body temperature. Opioid peptides were first investigated in hyperthermia, where it was found that μ-opioid receptor (MOR) agonists stimulate this response when injected into the periaqueductal gray (PAG) region of the brain. Xin et al. showed that delivery of dynorphin A1-17 (a KOR agonist) through microdialysis into the PAG region induced hypothermia in rats. The authors found that the severity of hypothermia was proportional to the dose of dynorphin A1-17 administered. Hypothermia could be prevented by administering KOR antagonist nor-BNI to the rat. Xin et al. hypothesized that while MOR agonists mediate hyperthermia, KOR agonists, such as dynorphin, mediate hypothermia. Sharma and Alm found that subjecting rats to heat (38˚C) caused dynorphins to be upregulated in the cerebral cortex, hippocampus, cerebellum, and the brain stem. Further, authors found that administration of nitric oxide synthase (NOS) inhibitors reduced dynorphin A1-17 levels in the brain and attenuated symptoms related to heat stress. Sharma and Alm concluded that hyperthermia increases dynorphin levels, which may cause damage and promote heat stress reaction. They further hypothesized that nitric oxide was part of this mechanism. Ansonoff et al. found that hypothermic effects are mediated through K1 (κ-opioid receptor 1), but not K2.
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Sources: en.wikipedia.org
Finally, Marshall and coworkers found that P-selectin:PSGL-1 bonds exhibited increasing bond lifetime as step loads were applied between 0 and ~10 pN for monomeric interaction but 1 and ~20 pN for dimeric interaction, exhibiting catch bond behavior; after reaching maximum values, which were ~0.6 and 1.2 seconds for monomeric and dimeric interaction, respectively, the bond lifetime fell rapidly at higher loads, displaying slip bond behavior ("catch-slip" bonds). These data were collected using an atomic force microscope and a flow chamber, and have subsequently been duplicated using a biomembrane force probe. These finding prompted the discoveries of other important catch bonds in the 2000s, including those between L-selectin and PSGL-1 or endoglycan, FimH and mannose, myosin and actin, platelet glycoprotein Ib and von Willebrand factor, and integrin alpha 5 beta 1 and fibronectin. Emphasizing their importance and general acceptance, in the three years following their discovery there were at least 24 articles published on catch bonds. More catch bonds were discovered in the 2010s, including E-selectin with carbohydrate ligands, G-actin with G-actin or F-actin, cadherin-catenin complex with actin, vinculin with F-actin, microtubule with kinetochore particle, integrin alpha L beta 2 and intercellular adhesion molecule 1 (ICAM-1), integrin alpha 4 beta 1 with vascular adhesion molecule 1, integrin alpha M beta 2 with ICAM-1, integrin alpha V beta 3 with fibronectin, and integrin alpha IIb beta 3 with fibronectin or fibrinogen.
=== Surgical irrigation solutions === BSS (ophthalmic irrigation solution) (produced by Alcon) Composition per 1 mL: sodium chloride (NaCl) 6.4 mg, potassium chloride (KCl) 0.75 mg, calcium chloride dihydrate (CaCl2·2H2O) 0.48 mg, magnesium chloride hexahydrate (MgCl2•6H2O) 0.3 mg, sodium acetate trihydrate (C2H3NaO2·3H2O) 3.9 mg, sodium citrate dihydrate (C6H5Na3O7·2H2O) 1.7 mg, sodium hydroxide and/or hydrochloric acid (to adjust pH), and water for injection. The pH is approximately 7.5. The osmolality is approximately 300 mOsm/Kg. BSS Plus (ophthalmic irrigation solution) (produced by Alcon) Composition per 1 mL (once preparation complete): sodium chloride 7.14 mg (122.17 mmol), potassium chloride 0.38 mg (5.097 mmol), calcium chloride dihydrate 0.154 mg (1.04754 mmol), magnesium chloride hexahydrate 0.2 mg (0.983767 mmol), dibasic sodium phosphate 0.42 mg (2.95858 mmol), sodium bicarbonate 2.1 mg (24.998 mmol), dextrose 0.92 mg (5.1067 mmol), glutathione disulfide (oxidized glutathione) 0.184 mg (0.3003 mmol), hydrochloric acid and/or sodium hydroxide (to adjust pH), in water for injection. The reconstituted product has a pH of approximately 7.4. Osmolality is approximately 305 mOsm.
== Plot == At the underground Black Mesa Research Facility, the theoretical physicist Gordon Freeman participates in an experiment on a crystal of unknown origin. This triggers a "resonance cascade", which greatly damages the facility and teleports in hostile alien creatures. Eli Vance tells Freeman to get to the surface and find help. After going through several layers of Black Mesa, Freeman discovers that United States Marines and black operators have been dispatched to the facility to terminate the aliens but also to cover up the incident by eliminating all the remaining Black Mesa personnel. A scientist instructs him to make his way to the Lambda Complex to stop the alien invasion. Freeman then discovers a monster called the Tentacle, and kills the giant creature using a rocket engine test facility that incinerates it, and uses an underground monorail to reach a rocket silo. He launches a satellite to help the Lambda team, but is captured by vengeful Marines and left for dead in a trash compactor. Escaping through a waste treatment complex, Freeman travels through a part of Black Mesa filled with alien specimens, collected long before the resonance cascade. Overpowered by the aliens, the Marines withdraw and begin to launch air strikes. Freeman crosses the facility's surface to reach the Lambda Complex, where he discovers secret teleportation technology. There, scientists inform him that a powerful alien creature is preventing them from closing the portal. They teleport him to the alien dimension Xen to kill it.
Sources: en.wikipedia.org
The peptide is Aib-His-D-2-Nal-D-Phe-Lys-NH2. Two of its residues are non-natural, which slows enzymatic degradation. The C-terminal amide is common among bioactive peptides.
It binds the same ghrelin receptor but with greater selectivity in functional assays. Preclinical work reports less cortisol and prolactin stimulation at growth-hormone-releasing doses. Those differences are relative, not absolute, and depend on dose and model.
No major regulatory authority has approved it for human therapeutic use. It is sold as a research chemical for laboratory investigation. Clinical status varies by country and is subject to change.
It acts on the growth hormone secretagogue receptor, GHS-R1a, which is also the receptor for ghrelin. Binding triggers intracellular signaling that promotes growth hormone release from the pituitary. The interaction is the basis for its classification as a secretagogue.