This is a working overview of growth hormone secretagogue, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-01 and is reviewed periodically as new material appears.
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.
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.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Value for the free base |
| Molar mass | 711.9 g/mol | Calculated from the formula |
| Appearance | White to off-white powder | Typical lyophilized form |
| Mechanism class | Ghrelin receptor agonist | Also described as a secretagogue |
| Half-life | About 2 hours | Reported for human circulation |
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.
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.
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.
Lyophilized ipamorelin is generally held at minus twenty degrees Celsius or colder, protected from light and moisture. In solution the peptide is less stable, and degradation proceeds through hydrolysis of the amide backbone, oxidation of the histidine residue, and aggregation. Repeated freeze-thaw cycles accelerate these processes, so dividing material into single-use aliquots before freezing is common practice in research settings. Buffered formulations near neutral pH tend to show the slowest degradation, while strongly acidic or basic conditions raise hydrolysis rates. Stability data specific to ipamorelin are sparse, and much guidance is extrapolated from other short peptides.
Quality control for research-grade ipamorelin is not governed by a single harmonized pharmacopeial monograph, so certificates of analysis vary between suppliers. Common tests include appearance, solubility, water content, peptide content by quantitative amino acid analysis, and residual counterion measurement. Independent verification by an outside laboratory is often used to confirm identity and purity claims. Salt form, counterion content, and residual solvent levels are frequently unspecified, which complicates direct comparison between lots and leaves reproducibility partly unresolved.
Lyophilized material is generally held at minus twenty degrees Celsius or lower, protected from moisture and light. Repeated excursions to room temperature cause condensation inside the vial and gradual moisture uptake, both of which shorten shelf life. Containers should be allowed to equilibrate before opening so that water does not condense on the solid. Dividing a batch into single-use aliquots reduces freeze-thaw cycling. Solid peptide handled this way is usually considered stable for months to years, while the same material in solution degrades on a much shorter timescale.
Common solvents for laboratory work include water, buffered saline, and dimethyl sulfoxide. Once dissolved, the peptide is exposed to hydrolysis and oxidation, and alkaline conditions accelerate breakdown. Low-binding plasticware and the addition of a carrier protein reduce losses to container surfaces, which can otherwise be substantial at low concentrations. Solutions are typically kept cold and used within days. Investigators working with the compound generally prepare fresh working dilutions rather than storing dilute stocks, and they avoid repeated warming of the same vial.
=== Hypersensitivity === Prior to the advent of the "human" lente insulins, the lente insulins (semi-lente, lente, and ultra-lente) were a combination of porcine and bovine insulin products that were filtered and combined with zinc to form the suspension. Even with product filtering, due to the animal origin, the human body might recognize the foreign protein as such and form antibodies against it. These reactions were slightly more likely with lente insulins than insulins derived from a solely porcine source, as bovine insulin was more immunogenic than porcine insulin.
=== Regulation by insulin in animals === In animals, regulation of blood glucose levels by the pancreas in conjunction with the liver is a vital part of homeostasis. The beta cells in the pancreatic islets are sensitive to the blood glucose concentration. A rise in the blood glucose concentration causes them to release insulin into the blood, which has an effect particularly on the liver, but also on fat and muscle cells, causing these tissues to remove glucose from the blood. When the blood sugar falls the pancreatic beta cells cease insulin production, but, instead, stimulate the neighboring pancreatic alpha cells to release glucagon into the blood. This, in turn, causes the liver to release glucose into the blood by breaking down stored glycogen, and by means of gluconeogenesis. If the fall in the blood glucose level is particularly rapid or severe, other glucose sensors cause the release of epinephrine from the adrenal glands into the blood. This has the same action as glucagon on glucose metabolism, but its effect is more pronounced. In the liver glucagon and epinephrine cause the phosphorylation of the key, regulated enzymes of glycolysis, fatty acid synthesis, cholesterol synthesis, gluconeogenesis, and glycogenolysis. Insulin has the opposite effect on these enzymes. The phosphorylation and dephosphorylation of these enzymes (ultimately in response to the glucose level in the blood) is the dominant manner by which these pathways are controlled in the liver, fat, and muscle cells.
Selenium shows borderline metalloid or nonmetal behaviour. Its most stable form, the grey trigonal allotrope, is sometimes called "metallic" selenium because its electrical conductivity is several orders of magnitude greater than that of the red monoclinic form. The metallic character of selenium is further shown by its lustre, and its crystalline structure, which is thought to include weakly "metallic" interchain bonding. Selenium can be drawn into thin threads when molten and viscous. It shows reluctance to acquire "the high positive oxidation numbers characteristic of nonmetals". It can form cyclic polycations (such as Se2+8) when dissolved in oleums (an attribute it shares with sulfur and tellurium), and a hydrolysed cationic salt in the form of trihydroxoselenium(IV) perchlorate [Se(OH)3]+·ClO–4. The nonmetallic character of selenium is shown by its brittleness and the low electrical conductivity (~10−9 to 10−12 S•cm−1) of its highly purified form. This is comparable to or less than that of bromine (7.95×10–12 S•cm−1), a nonmetal. Selenium has the electronic band structure of a semiconductor and retains its semiconducting properties in liquid form. It has a relatively high electronegativity (2.55 revised Pauling scale). Its reaction chemistry is mainly that of its nonmetallic anionic forms Se2−, SeO2−3 and SeO2−4. Selenium is commonly described as a metalloid in the environmental chemistry literature.
The body of the royal angelfish is moderately elongate and is very compressed. The preorbital bone is convex and has no strong spines. There is 1 prominent spine at an angle at the preopercal. The ventral edge of the interopercle is smooth. The eyes are moderately small along with the mouth that is terminal. The mouth is also protractile. They have a maximum length of 25.0 cm (9.8 in). They have a total of 14 dorsal spines, and 17–19 soft dorsal rays. They have 3 anal spines and 17–19 anal soft rays. They also have 16–17 pectoral fin rays. Their caudal fin is rounded. The precise coloration of this fish can vary as regional differences can occur, most notably in populations from the Indian Ocean, Red Sea, and South Pacific Ocean. A commonality, however, is a body edged in narrow blue-white and orange stripes that are narrow and angle backward. The posterior portion of dorsal fin is black or blue with close-set blue dots, and the posterior portion of anal fin has alternating yellow and blue bands running parallel to body contour. The caudal fin is yellow. Juveniles are colored with a large dark spot on basal portion of the soft dorsal fin. They have been reported of living 15 years. Recent research indicates that the Pygoplites comprises two morphs, with the variants potentially hybridizing at Christmas Island.
Ligaments Anterior cruciate ligament (knee), medial collateral ligament (knee), ulnar collateral ligaments (wrist/hand), interspinous ligaments (vertebrae) Muscles Biceps brachii (upper arm), rectus femoris (thigh), transverse abdominis (abdominals) Tendons Patellar tendon (knee), calcaneal/Achilles tendon (foot/lower leg), biceps tendon (shoulder/elbow) Cartilage Menisci (knee), intervertebral discs (spine), acetabulum (hip)
Sources: en.wikipedia.org
== Function == Excitatory amino acid transporter 3 is a member of the high-affinity glutamate transporters which plays an essential role in transporting glutamate across plasma membranes in neurons. In the brain, excitatory amino acid transporters are crucial in terminating the postsynaptic action of the neurotransmitter glutamate, and in maintaining extracellular glutamate concentrations below neurotoxic levels. EAAT3 also transports aspartate, and mutations in this gene are thought to cause dicarboxylic aminoaciduria, also known as glutamate-aspartate transport defect. EAAT3 is also the major route of neuronal cysteine uptake. Cysteine is a component of the major antioxidant glutathione, and mice lacking EAAT3 exhibit reduced levels of glutathione in neurons, increased oxidative stress, and age-dependent loss of neurons, especially neurons of the substantia nigra. A meta-analysis identified a small but significant association between a polymorphism of the gene SLC1A1 and obsessive–compulsive disorder.
Replacement of the phenyl portion of the phenethyl group by any monocycle, whether or not further substituted in or on the monocycle; substitution in or on the phenethyl group with alkyl, alkenyl, alkoxyl, hydroxyl, halo, haloalkyl, amino or nitro groups; substitution in or on the piperidine ring with alkyl, alkenyl, alkoxyl, ester, ether, hydroxyl, halo, haloalkyl, amino or nitro groups; replacement of the aniline ring with any aromatic monocycle whether or not further substituted in or on the aromatic monocycle; and/or replacement of the N-propionyl group by another acyl group."
genetic distance A measure of the genetic divergence between species, populations within a species, or individuals, used especially in phylogenetics to express either the time elapsed since the existence of a common ancestor or the degree of differentiation in the DNA sequences comprising the genomes of each population or individual.
== Clinical significance == Gastroesophageal reflux disease (GERD) is a common disorder that occurs when stomach acid repeatedly flows back into the esophagus, this backwash of acid (reflux) also known as heartburn can irritate the lining of the esophagus. Most people are able to manage the discomfort of GERD with lifestyle changes and medications, notably proton pump inhibitors, and H2 blockers. Antacids may also be used to neutralise gastric acid. Sometimes, surgery may be needed to ease symptoms. Chronic inflammation of the gastric mucosa can lead to atrophic gastritis resulting in a decreased secretion of gastric acid, and consequent digestive problems. In hypochlorhydria and achlorhydria, gastric acid is either low or absent, respectively. This can potentially lead to less protection against ingested pathogens such as Vibrio or Helicobacter bacteria. In Zollinger–Ellison syndrome gastrin levels are increased, leading to excess gastric acid production, which can cause gastric ulcers. Hypercalcemia also increases gastrin and gastric acid and can cause ulcers. In diseases featuring excess vomiting, hypochloremic metabolic alkalosis (decreased blood acidity by H+ and chlorine depletion) may develop.
Sources: en.wikipedia.org
It has not been approved as a therapeutic by major regulators, and the human trial record is small and dated. Material available today is mostly sold as a research chemical for laboratory use. Approval and restriction status varies by country.
It binds the ghrelin receptor, known as the growth hormone secretagogue receptor type 1a. Activation of that receptor triggers signaling that leads to growth hormone release. Selectivity for growth hormone over cortisol and prolactin is the property most often cited for this compound.
Published estimates place the circulating half-life at roughly two hours in humans. Clearance involves peptidase activity and renal handling. Because the peptide is short-lived, release patterns after administration are usually described as pulsatile rather than sustained.
两者都是 GHS-R1a 激动剂，但 ipamorelin 在研究中显示出更高的生长激素释放选择性。早期资料显示它对皮质醇、催乳素与食欲的刺激弱于 GHRP-6。这些差异是相对程度，而非绝对区分。