Everything below concerns GHS-R1a. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-12-19. 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.
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.
The compound was developed at Novo Nordisk during the 1990s as part of a programme seeking secretagogues with improved selectivity. It was described in the peer-reviewed literature in 1998 alongside related pentapeptides from the same series. Investigators advanced it because it raised growth hormone output in animal models while leaving other pituitary hormones comparatively unaffected. The development code NNC 26-0161 appears in earlier reports, and ipamorelin later became the common designation in published work.
| 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。
Published animal and early human work describes growth hormone release that is separated from comparable rises in adrenocorticotropic hormone and cortisol. Prolactin changes are reported as small in the same studies. Selectivity is attributed to binding at the ghrelin receptor and to the downstream signaling that follows, rather than to differences in how quickly the peptide is cleared. Authors commonly label the compound selective rather than potent, because the same mass produces a smaller growth hormone response than some older secretagogues tested in parallel. Whether that profile holds across species and routes of administration remains an open question.
Human data remain limited and come mainly from small, short-term studies conducted decades ago. The peptide has not received approval as a medicine from major regulators, so current availability is largely as a research chemical. Reported effects on growth hormone pulsatility, appetite, and body composition should be read as preliminary, since few independent groups have replicated the original findings. Analytical characterization of research-grade material varies between suppliers, which complicates comparison across studies. Regulatory status also differs by country, and some jurisdictions classify it as a prescription-only or otherwise restricted item.
Ipamorelin is a synthetic pentapeptide first described in the 1990s by researchers at Novo Nordisk during a program to develop selective growth hormone secretagogues. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues, alpha-aminoisobutyric acid and D-2-naphthylalanine. The C-terminus is amidated, and the material is supplied as a white lyophilized powder. The molecular formula is C38H49N9O5 and the monoisotopic mass is approximately 711.85 daltons. The short chain and modified residues give it greater resistance to enzymatic degradation than many larger peptide hormones.
At the molecular level, ipamorelin acts as an agonist at the growth hormone secretagogue receptor type 1a, the same G protein-coupled receptor that binds ghrelin. Receptor activation couples to Gq/11 signaling, raising intracellular calcium through inositol trisphosphate and diacylglycerol, which in turn promotes exocytosis of growth hormone from pituitary somatotroph cells. Ipamorelin binds this receptor with high affinity and shows weak activity at other secretagogue-related targets in vitro. Its action requires the intact receptor and is not reversed by growth hormone-releasing hormone antagonists.
Compared with earlier growth hormone secretagogues such as GHRP-6 and hexarelin, ipamorelin has been reported to produce less stimulation of adrenocorticotropic hormone, cortisol, and prolactin in animal and early human studies. This selectivity is usually attributed to differences in receptor subtype interactions and to the tissue distribution of the receptor. Effects on appetite appear weaker than those of ghrelin itself, although the supporting evidence base is small. Whether these differences produce a distinct clinical profile remains an open question, since controlled human trials are limited.
=== Anatomy === The blood-brain barrier protects the brain by restricting the ability of large molecules to cross the barrier between the blood, CSF, and interstitial fluid of the brain. ICV injection circumvents this barrier, to be able to deliver drugs to the CSF. An ICV device is implanted under the scalp, into the subgaleal space where it is then connected to the ventricles with an outlet catheter. This allows for repeated doses of the drug without having to re-puncture the scalp. Production of CSF is at a rate of about .3 mL/minute and occurs at the ependymal and parenchymal regions and the choroid plexus. Up to 80 percent of CSF production comes from the choroid plexus, which is present within the lateral, third, and fourth ventricles. The choroid is lined with epithelium with tight junctions at the ventricular side of the cells. This comprises the blood-CSF barrier. Whereas the blood-brain barrier is made up of vascular endothelium in capillary beds throughout the CNS parenchyma.
Prolactin-releasing peptide (PrRP) is a peptide hormone that in humans is encoded by the PRLH gene. PrRP binds to the receptor PrRPR and seems to be involved in appetite regulation, but its precise function isn’t fully understood. Though early research suggested that PrRP stimulates prolactin (PRL) release, hence its name, this potential function is debated. Unlike other anterior pituitary hormones, the hypothalamus seems to primarily regulate prolactin release through inhibition, mostly via dopamine as part of the hypothalamic–pituitary–prolactin axis.
The Industrial Revolution in Japan occurred during the Meiji era. The industrial revolution began around 1870 as Meiji era leaders decided to catch up with the West. The government built its first railroads, improved roads, and inaugurated a land reform program to prepare the country for further development. It inaugurated a new Western-based education system for all young people, sent thousands of students to the United States and Europe, and hired more than 3,000 Westerners to teach modern science, mathematics, technology, and foreign languages in Japan (O-yatoi gaikokujin). In 1871, a group of Japanese politicians known as the Iwakura Mission toured Europe and the US to learn western ways. The result was a deliberate state-led industrialization policy to enable Japan to quickly catch up. Japan developed modern industry through direct state intervention. Government-owned enterprises were important to the development of key economic sectors like railways. Through government connections, major private enterprises received various forms of financial support from the state. Modern industry first appeared in textiles, including cotton and especially silk, which was based in home workshops in rural areas. Due to the importing of new textile manufacturing technology from Europe, between 1886 and 1897, Japan's total value of yarn output rose from 12 million to 176 million yen. In 1886, 62% of yarn in Japan was imported; by 1902, most yarn was produced locally.
The pathway of wing expansion is regulated by a signal-receptor pathway, where the neurohormone bursicon interacts with its complementary G protein-coupled receptor; this receptor drives one of the G-protein subunits to signal further enzyme activity and results in development in the wing, such as apoptosis and growth. se: sepia – The eye color of the sepia mutant is sepia, a reddish-brown color. In wild-type flies, ommochromes (brown) and drosopterins (red) give the eyes the typical red color. The drosopterins are made via a pathway that involves a pyrimidodiazepine synthase, which is encoded on chromosome 3L. The gene has a premature stop codon in sepia flies, so that the flies cannot produce the pyrimidodiazepine synthase and thus no red pigment, so that the eyes stay sepia. The sepia allele is recessive and thus offspring from sepia flies and homozygous wild type flies, has red eyes. The sepia phenotype does not depend on the sex of the fly. v: vermilion – The vermilion mutants cannot produce the brown ommochromes leaving the red drosopterins so that the eyes are vermilion colored (a radiant red) compared to a wild-type D. melanogaster. The vermilion mutation is sex-linked and recessive. The gene that is defective lies on the X chromosome. The brown ommochromes are synthesised from kynurenine, which is made from tryptophane. Vermilion flies cannot convert tryptophane into kynurenine and thus cannot make ommochromes, either. Vermilion mutants live longer than wild-type flies.
These findings mirror human epidemiological data showing a link between nicotine use and increased risk of later cannabis and cocaine use, as well as other substances. Similarly, in rats, alcohol consumption raises the probability of later cocaine addiction and is associated with changes in the brain's reward system. Human studies also show that alcohol use increases the risk of transitioning from cocaine use to addiction. Experimentally, cocaine injections can be delivered to animals such as fruit flies to study the mechanisms of cocaine addiction.
Sources: en.wikipedia.org
In 1996, it became a contract research organization (CRO) for the biopharmaceutical sector and entered into collaboration with SmithKline Beecham biologicals (Rixensart, Belgium) for the production of recombinant proteins for phase I, II and III clinical trials. In addition to its pharmaceutical manufacturing activities, Eurogentec became a service company for the biotechnical research industry and university laboratories. In 1999, Eurogentec acquired Oswel Research Product Ltd. a biotechnology company based in Southampton, Great Britain and specialized in the synthesis of chemically modified and complex oligonucleotides and their analogues (DNA, RNA, PNA). In 2002, Eurogentec acquired Wita Proteomics, a company specialized in proteomics services, based in Berlin (Germany). A few months later, Eurogentec installed its US office in San Diego for the production of oligonucleotides (EGT NA).
Their KOR agonism may be involved in ibogaine's putative antiaddictive effects in the setting of opioid dependence. Analogues with strongly enhanced KOR agonist potency such as oxa-noribogaine, GM-3009, and 4-allyl-6-oxa-noribogainalog have been developed. GM-3009 is under development by Gilgamesh Pharmaceuticals for the treatment of opioid-related disorders. The selective KOR agonist and benzomorphan MR-2034 ((–)-MR-2033) led to the initial discovery in the 1980s that KOR agonists produce hallucinogenic and dysphoric effects as opposed to these effects being mediated by concomitant sigma receptor agonism.
Apiin (apigenin 7-O-apioglucoside), isolated from parsley and celery Apigetrin (apigenin 7-glucoside), found in dandelion coffee Vitexin (apigenin 8-C-glucoside) Isovitexin (apigenin 6-C-glucoside) Rhoifolin (apigenin 7-O-neohesperidoside) Schaftoside (apigenin 6-C-glucoside 8-C-arabinoside)
Synovial cavity: all diarthroses have the characteristic space between the bones that is filled with synovial fluid. Joint capsule: the fibrous capsule, continuous with the periosteum of articulating bones, surrounds the diarthrosis and unites the articulating bones; the joint capsule consists of two layers - (1) the outer fibrous membrane that may contain ligaments and (2) the inner synovial membrane that secretes the lubricating, shock absorbing, and joint-nourishing synovial fluid; the joint capsule is highly innervated, but without blood and lymph vessels, and receives nutrition from the surrounding blood supply via either diffusion (slow), or via convection (fast, more efficient), induced through exercise. Articular cartilage: the bones of a synovial joint are covered by a layer of hyaline cartilage that lines the epiphyses of the joint end of the bone with a smooth, slippery surface that prevents adhesion; articular cartilage functions to absorb shock and reduce friction during movement. Many, but not all, synovial joints also contain additional structures:
Sources: en.wikipedia.org
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.