If you have been reading about GHSR-1a and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-04-16. Numbers and descriptions here follow the published literature rather than marketing material.
Structural features distinguish the molecule from earlier secretagogues. An alpha-aminoisobutyric acid residue near the N-terminus and a D-naphthylalanine substitution increase receptor affinity, while C-terminal amidation improves resistance to exopeptidases. These modifications are associated with reduced stimulation of appetite and of the hypothalamic-pituitary-adrenal axis compared with hexarelin or growth hormone releasing peptide-6. Whether the same profile applies at every dose level studied is a matter of ongoing investigation rather than settled consensus.
Ipamorelin is a synthetic pentapeptide that acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. Its sequence incorporates non-natural residues, which slows enzymatic breakdown relative to short native peptides. In laboratory and early clinical work the compound is described as a selective growth hormone secretagogue because it raises growth hormone with comparatively little effect on other pituitary outputs. The degree to which that selectivity holds across species and dosing regimens remains an open question in the published literature.
Signal transduction begins when the peptide binds GHSR-1a on pituitary somatotrophs. The receptor couples to Gq/11 proteins, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate into inositol trisphosphate and diacylglycerol. Inositol trisphosphate releases calcium from intracellular stores, and the resulting rise in cytosolic calcium drives growth hormone vesicle fusion. Concurrent Gs coupling and cyclic AMP elevation have also been reported, and the relative contribution of each arm to the overall secretory response is not fully settled.
Selectivity is the property most often attached to this peptide. Published animal and early human studies record increases in growth hormone release after administration, with adrenocorticotropic hormone and cortisol responses remaining small by comparison. Effects on appetite-related pathways also appear weaker than those reported for several earlier secretagogues. Reviews that compare members of the growth hormone secretagogue family cite these findings frequently, though the receptor-level explanation for the selectivity continues to be debated rather than settled.
Ipamorelin is a synthetic pentapeptide classified as a growth hormone secretagogue. Its sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combines three non-proteinogenic residues with a C-terminal amide. The N-terminal aminoisobutyric acid unit and the two aromatic D-amino acids distinguish it from peptides assembled only from standard L-amino acids. Its formula is C38H49N9O5, corresponding to an average mass near 711.9 Da. At neutral pH the molecule carries a net positive charge, a property that shapes its behaviour in chromatographic and electrophoretic systems.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Reported for the free peptide |
| Molecular mass | 711.85 Da | Monoisotopic value |
| Residue motif | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Non-natural residues at positions one and three |
| Primary target | GHSR-1a | Ghrelin receptor, G protein coupled |
| Reported plasma half-life | About two hours | Values vary with assay and subject group |
在 GHS 家族中，早期肽类如 GHRP-6 与 GHRP-2 会同时促进生长激素、皮质醇与催乳素的释放，并明显增加食欲。Ipamorelin 在动物与早期人体研究中表现出对生长激素释放的相对选择性，对上述其他激素的影响较小。这种差异通常归因于受体结合模式与下游信号偏向的不同，而完整的分子解释仍有待补充。需要区分的是，选择性是研究观察中的相对程度，并非绝对界限。
从用途定位看，ipamorelin 目前主要以研究用肽的身份被讨论，未见主要药品监管机构将其批准为治疗药物。市售材料通常标注仅供研究使用，不得用于人体或诊断程序。文献中它常与生长激素促分泌素、GHS-R1a 激动剂、胃饥饿素拟似物等表述并列出现。既有研究的样本量普遍偏小，因此对其效应强度与一致性的描述应保持谨慎。
Ipamorelin 是一种合成五肽，序列为 Aib-His-D-2-Nal-D-Phe-Lys-NH2，分子式 C38H49N9O5，游离碱分子量约 711.85 g/mol。它属于生长激素促分泌素（GHS）家族，作用靶点是胃饥饿素受体 GHS-R1a。该化合物由诺和诺德的研究团队在二十世纪九十年代末报道，设计目标是提高对生长激素释放的选择性。C 端酰胺化与 N 端 Aib 残基是两个用于抵抗肽酶降解的结构特征。
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class. It acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. The compound was designed in the 1990s during a search for agents that release growth hormone with fewer off-target hormonal effects than earlier secretagogues. It appears in the research literature under several sequence-based names. Material supplied for laboratory work is normally a lyophilized solid, and it is not marketed as an approved therapeutic in major jurisdictions.
The molecule contains five residues, including alpha-aminoisobutyric acid, D-2-naphthylalanine, and D-phenylalanine, and it ends in a lysine amide. Non-natural and D-configured residues make the chain less susceptible to common peptidases, which helps explain its resistance to rapid breakdown. Its molecular formula is C38H49N9O5, corresponding to a free-base mass near 711.9 daltons. The C-terminal amide removes a negative charge and is a recurring feature in receptor-active peptides of this family. These structural choices are usually discussed as the basis for its selectivity profile.
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=== Overlay === Translucent or sheer fabrics are used to stabilize the textile without altering its appearance. This is typically done using nylon netting, silk crepeline, or polyester Tetex. Overlay is generally applied to textiles too fragile to withstand localized stitching methods. Overlay materials may be stitched to a more stable backing fabric.
In 1940–1941, some 325,000 Polish citizens were deported by the Soviet Union. The number of Polish citizens who died at the hands of the Soviets is estimated at less than 100,000. In 1943–1944, Ukrainian nationalists associated with the Organization of Ukrainian Nationalists (OUN) and the Ukrainian Insurgent Army perpetrated the Massacres of Poles in Volhynia and Eastern Galicia. Estimates of the number of Polish civilian victims vary greatly, from tens to hundreds of thousands. Approximately 90% of Poland's war casualties were the victims of prisons, death camps, raids, executions, the annihilation of ghettos, epidemics, starvation, excessive work and ill treatment. The war left one million children orphaned and 590,000 persons disabled. The country lost 38% of its national assets (whereas Britain lost only 0.8%, and France only 1.5%). Nearly half of pre-war Poland was expropriated by the Soviet Union, including the two great cultural centers of Lwów and Wilno. The policies of Nazi Germany have been judged after the war by the International Military Tribunal at the Nuremberg trials and Polish genocide trials to be aimed at extermination of Jews, Poles and Roma, and to have "all the characteristics of genocide in the biological meaning of this term".
=== United States === Similar to the law of Canada, the U.S. law (27 CFR 5.148) says that tequila must be "made in Mexico, in compliance with the laws and regulations of Mexico governing the manufacture of Tequila for consumption in that country."
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== Normal levels == Progesterone is used as part of hormone replacement therapy in people who have low progesterone levels, and for other reasons. For purposes of comparison with normal physiological circumstances, luteal phase levels of progesterone are 4 to 30 ng/mL, while follicular phase levels of progesterone are 0.02 to 0.9 ng/mL, menopausal levels are 0.03 to 0.3 ng/mL, and levels of progesterone in men are 0.12 to 0.3 ng/mL. During pregnancy, levels of progesterone in the first 4 to 8 weeks are 25 to 75 ng/mL, and levels are typically around 140 to 200 ng/mL at term. Production of progesterone in the body in late pregnancy is approximately 250 mg per day, 90% of which reaches the maternal circulation.
Circularly polarised ultraviolet light has been shown to generate L-excesses in crystallising amino acids for experimental conditions mimicking alteration on asteroids, and this is thought to be the dominant extraterrestrial source of chiral symmetry breaking (i.e., the favouring of one enantiomer over another). It is notable that only excesses of the L-enantiomer have been observed in extraterrestrial amino acids, suggesting that the abiotic process responsible for enantiomeric enrichments may be the original source of the L-amino acid selectivity currently observed in terrestrial life.
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== Academic background == Gerngross received a M.S. (Dipl. Ing.) in chemical engineering (1989) and later a Ph.D. in molecular biology from the Technical University of Vienna, Austria. Following his studies in Austria he became a visiting scientist at the Massachusetts Institute of Technology in the laboratory of the late Arnold Demain (1989–91) and later joined the laboratory of Anthony Sinskey and JoAnne Stubbe at MIT as a postdoctoral associate from 1991 to 1993. From 1993 till 1998 he headed the fermentation and process development group at Metabolix Inc., a small startup company in Cambridge, Massachusetts. In 1998 he left industry to join the faculty at Dartmouth where he focused his research on protein engineering, glycoprotein engineering in yeast, and life cycle analysis of competing manufacturing technologies. In addition to this work, Gerngross’ lab also developed a novel protein expression system based on the industrial fermentation organisms Ralstonia eutropha, formerly Alcaligenes eutrophus. With certain model proteins, this expression system has shown to outperform E. coli, the well proven workhorse of prokaryotic protein expression. The work on Ralstonia eutropha was later expanded in collaboration with Prof. Wood at Princeton University to combine recombinant expression of proteins with the ability to purify them in vivo. In the late 1990s Gerngross became one of the first vocal critics of biobased processes.
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The I1 receptor appears to be a G protein-coupled receptor that is localized on the plasma membrane. It may be coupled to PLA2 signalling and thus prostaglandin synthesis. In addition, activation inhibits the sodium-hydrogen antiporter and enzymes of catecholamine synthesis are induced, suggesting that the I1 receptor may belong to the neurocytokine receptor family, since its signaling pathways are similar to those of interleukins. It is found in the neurons of the reticular formation, the dorsomedial medulla oblongata, adrenal medulla, renal epithelium, pancreatic islets, platelets, and the prostate. They are notably not expressed in the cerebral cortex or locus coeruleus. Animal research suggests that much of the antihypertensive action of imidazoline drugs such as clonidine is mediated by the I1 receptor. In addition, I1 receptor activation is used in ophthalmology to reduce intraocular pressure. Other putative functions include promoting Na+ excretion and promoting neural activity during hypoxia.
The musculoskeletal system consists of the human skeleton (which includes bones, ligaments, tendons, joints and cartilage) and attached muscles. It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in the body contain bone marrow, the site of production of blood cells. Also, all bones are major storage sites for calcium and phosphate. This system can be split up into the muscular system and the skeletal system.
Cecropin A Peptide Sequence (KWKLFKKIEKVGQNIRDGIIKAGPAVAVVGQATQIAK). Secondary structure includes two α helices. At low peptide to lipid ratios ion channels are formed, at high peptide to lipid ratios pores are formed. Cecropin B Peptide Sequence (KWKVFKKIEKMGRNIRNGIVKAGPAIAVLGEAKAL). Secondary structure includes two α helices. CECD from Aedes aegypti (Yellowfever mosquito). Papiliocin from Papilio xuthus (a butterfly) Cecropin P1 Peptide Sequence (SWLSKTAKKLENSAKKRISEGIAIAIQGGPR). An antibacterial peptide from Ascaris suum, a parasitic nematode that resides in the pig intestine, also belongs to this family.
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Both molecules activate the same receptor, GHSR-1a, but they share little sequence identity. Ghrelin is a 28-amino-acid hormone carrying a distinctive acyl modification, whereas ipamorelin is a short synthetic peptide. The shared target explains overlapping endocrine effects, while the different structures account for differences in metabolic stability and receptor selectivity.
Early animal and human studies reported growth hormone release at levels that produced small changes in cortisol, prolactin and adrenocorticotropic hormone. That contrast with older secretagogues gave rise to the selectivity label. The observation is consistent across several reports but rests on a limited number of small studies.
Plasma peptidases cleave the molecule into smaller fragments, and reported half-lives in human studies are on the order of a couple of hours. The identity and activity of individual breakdown products have not been fully mapped. Questions about tissue-level clearance remain open.
It is a synthetic five-amino-acid peptide that acts as a growth hormone secretagogue. Three of its residues are non-standard amino acids, and the chain ends in an amide rather than a free acid. The molecule is small enough that it can be characterised by routine peptide analytical techniques.