The short version of GHS-R1a fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-18 and is reviewed periodically as new material appears.
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.
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, and its molecular mass is approximately 711.9 daltons. The compound was described in the late 1990s by researchers seeking molecules that release growth hormone with fewer side effects than earlier secretagogues. It is a laboratory and research compound, not an approved medicine in most jurisdictions.
At the molecular level, ipamorelin acts as an agonist at the growth hormone secretagogue receptor, also called the ghrelin receptor or GHS-R1a. Binding to this receptor on pituitary somatotroph cells triggers a signaling cascade that leads to growth hormone release. The effect is mediated through phospholipase C and calcium mobilization rather than through the cyclic AMP pathway used by growth hormone releasing hormone. The two pathways are complementary, and combined stimulation produces a larger response than either alone.
Compared with other secretagogues such as GHRP-2, GHRP-6, and hexarelin, ipamorelin is described as more selective. Published animal work reports little or no increase in adrenocorticotropic hormone, cortisol, or prolactin at doses that release growth hormone. This selectivity is the property most often cited in the research literature. Whether the same profile holds across species and dosing schedules remains an open question, since human data are limited and come largely from small studies.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Pentapeptide with C-terminal amide |
| Average mass | Approximately 711.9 Da | Value derived from the formula |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and aqueous acetonitrile | Dissolution aided by acidic diluents |
| Common synonyms | Ipamorelin; NNC 26-0161 | Code name used in early reports |
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。
现有文献多来自小规模、短期的研究，涉及生长激素缺乏、术后肠麻痹等方向。长期使用是否导致受体脱敏，以及重复给药后效应是否衰减，仍属开放问题。不同研究之间的剂量、给药途径和受试者特征差异较大，因此结论外推需谨慎。关于临床获益的确切证据尚不充分，需要更大规模的对照试验来澄清。
Identity and purity assessment for a research peptide of this kind typically combines reversed-phase high-performance liquid chromatography with mass spectrometry. The chromatographic run separates related impurities and yields a purity percentage, while electrospray ionization or matrix-assisted laser desorption mass spectrometry confirms the expected molecular mass. Amino acid analysis or tandem mass spectrometry sequencing can add confidence when material is intended for quantitative work. Laboratories differ in how they calculate and report purity, so figures from different sources are not always directly comparable.
Lyophilized material is generally stored cold and dry, with desiccant, and protected from light. In solution the peptide is more vulnerable: the histidine side chain can oxidize, and repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. A mildly acidic aqueous buffer is often used for short-term handling because it limits several degradation routes. Accurate prediction of long-term stability under a given set of conditions is difficult, and published stability data remain sparse.
Published discussion of this compound is uneven. Some references describe it as a tool for probing growth hormone regulation, while others focus on analytical characterization or on comparisons with related secretagogues. Statements about selectivity, half-life and potency often trace back to a small number of original reports that later authors cite secondhand. Readers evaluating a claim should therefore check whether a figure reflects a direct measurement or a repeated citation, and whether the underlying study was conducted in animals, in isolated cells or in human volunteers.
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.
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.
Storage recommendations for ipamorelin usually focus on temperature, moisture, and light. Lyophilized powder is typically held at or below minus twenty degrees Celsius in a desiccated container protected from light. Reconstituted solutions are often aliquoted and stored at minus eighty degrees Celsius to reduce repeated freeze-thaw cycles, which can promote aggregation or degradation. The optimal buffer and pH depend on the specific assay, and no single condition applies to every experimental context. Peptide stability should be assessed with time-point measurements rather than assumed from general handling rules.
In the scientific literature, ipamorelin appears mainly in preclinical studies, receptor binding assays, and reviews of growth hormone secretagogues. Authors often discuss its selectivity profile alongside limitations such as small sample sizes, short study durations, and differences between species. Some papers examine pharmacokinetics and clearance, but human data are limited and not sufficient to define general clinical effects. Regulatory discussion treats the compound as an investigational or research substance rather than an approved therapy in most jurisdictions. Open questions include oral bioavailability, long-term endocrine effects, and whether selectivity observed in animals persists in humans.
== Multi domain proteins == The adhesome contains multi domain proteins with various functions, some of which are specifically enriched in the adhesome compared to the cell proteome. Protein domains enriched in the adhesome include: Pleckstrin homology (PH) and FERM domains, which target proteins to the plasma membrane; Calponin homology (CH) domain, which is an F-actin binding motif; Src homology 2 (SH2) domain, which mediate interaction with phosphorylated tyrosine residues; armadillo (ARM) GUK and LIM domains, which mediate specific protein-protein binding. The literature-based adhesome contains enzymes, such as protein tyrosine and serine/threonine kinases and phosphatases, guanine nucleotide exchange factors and GTPase activating proteins, E3-ligases and proteases, that regulate adhesion through post translational modification of the many structural and scaffolding proteins found in the adhesome. The proteomic-based studies have identified many proteins from functional groups that haven't previously been associated with cell adhesion sites, such as proteins involved in RNA splicing, translation, trafficking, golgi, endoplasmic reticulum, and metabolic enzymes. Whether these proteins are indeed an integral part of the adhesome or an artifact of the proteomic methods remains to be seen.
== Sequels == Half-Life 2 was followed by the episodic sequels Episode One (2006) and Episode Two (2007). After canceling Episode Three and several further Half-Life projects, Valve released a prequel, Half-Life: Alyx, in 2020.
Actinides seem to be a little less hard than lanthanides, probably due to a longer spatial extent of 5f atomic orbitals with respect to 4f ones, then a selective separation is possible thanks to ligands bearing soft donors such as nitrogen and sulfur atoms, by a different bonding nature compared to hard donors. Despite the potential separation of actinides, a direct extraction from the PUREX raffinate is very hard, due to the presence of many other interfering species in the feed such as activation and fission products. In this perspective, advanced separation processes involving very selective extracting agents are required to achieve an efficient partitioning for the following transmutation process. To sum up, knowledge of hydration, acid-base interactions, kinetics and thermodynamic stabilities and speciation of actinide and lanthanide ions with ligands is of great value to understand a solvent extraction process and to design new and promising extracting agents.
Sources: en.wikipedia.org
== Medical uses == Atenolol is used for a number of conditions including hyperthyroidism, hypertension, angina, long QT syndrome, acute myocardial infarction, supraventricular tachycardia, ventricular tachycardia, essential tremor (ET), and the symptoms of alcohol withdrawal. The role for β-blockers in general in hypertension was downgraded in June 2006 in the United Kingdom, and later in the United States, as they are less appropriate than other agents such as ACE inhibitors, calcium channel blockers, thiazide diuretics and angiotensin receptor blockers, particularly in the elderly. Atenolol has been used to treat anxiety disorders, such as generalized anxiety disorder and social anxiety disorder. It is thought that beta blockers do not directly treat psychological symptoms of anxiety, but can help control physical symptoms such as palpitations, and this may interfere with a positive feedback loop to indirectly reduce psychological anxiety. A 2025 systematic review and meta-analysis that included atenolol found widespread prescription of beta blockers for treatment anxiety disorders, but found no evidence of a beneficial effect relative to placebo or benzodiazepines in people with social phobia or panic disorder. However, the quality of evidence, including both numbers of studies and patients as well as quality and risk of bias of those studies, was limited.
== Veterinary uses == A number of veterinary medicine teaching hospitals are participating in a long-term clinical study examining the effect of rapamycin on the longevity of dogs. A clinical trial led by NC State College of Veterinary Medicine (HALT), run at a number of veterinary hospitals across the US, found that rapamycin reverses the effects of hypertrophic cardiomyopathy in cats. In March 2025, the US Food and Drug Administration announced conditional approval of sirolimus delayed-release tablets (Felycin-CA1) for the management of ventricular hypertrophy in cats with subclinical hypertrophic cardiomyopathy. This is the first product approved for use in cats with hypertrophic cardiomyopathy for any indication. Cardiomyopathy is a disease of the heart muscle. Hypertrophic cardiomyopathy in cats causes thickening of the heart's left ventricle. It is the most common heart disease in cats and is one of the most common causes of death in cats. While the cause is unknown in most cases, hypertrophic cardiomyopathy is associated with a genetic mutation in certain breeds, such as Maine Coons, Ragdolls, and Persians. Hypertrophic cardiomyopathy is a progressive disease. Cats in the subclinical phase have thickening of their heart wall but do not show clinical symptoms of the disease yet. Cats may live for years in the subclinical phase, while others may progress to congestive heart failure, arterial thromboembolism, or sudden death.
A given stereocenter has two possible configurations (R and S), which give rise to stereoisomers (diastereomers and enantiomers) in molecules with one or more stereocenter. For a chiral molecule with one or more stereocenter, the enantiomer corresponds to the stereoisomer in which every stereocenter has the opposite configuration. An organic compound with only one stereogenic carbon is always chiral. On the other hand, an organic compound with multiple stereogenic carbons is typically, but not always, chiral. In particular, if the stereocenters are configured in such a way that the molecule can take a conformation having a plane of symmetry or an inversion point, then the molecule is achiral and is known as a meso compound. Molecules with chirality arising from one or more stereocenters are classified as possessing central chirality. There are two other types of stereogenic elements that can give rise to chirality, a stereogenic axis (axial chirality) and a stereogenic plane (planar chirality). Finally, the inherent curvature of a molecule can also give rise to chirality (inherent chirality). These types of chirality are far less common than central chirality. BINOL is a typical example of an axially chiral molecule, while trans-cyclooctene is a commonly cited example of a planar chiral molecule. Finally, helicene possesses helical chirality, which is one type of inherent chirality. Chirality is an important concept for stereochemistry and biochemistry.
== Incenter == The incenter of a tangential quadrilateral lies on its Newton line (which connects the midpoints of the diagonals). The ratio of two opposite sides in a tangential quadrilateral can be expressed in terms of the distances between the incenter I and the vertices according to
Sources: en.wikipedia.org
== Causes == The cause of pattern hair loss is not yet fully understood. It appears to be the result of genetic changes that make the activity of hair follicles on the scalp become sensitive to the presence of androgenic hormones, cholesterol, and proteins such as insulin-like growth factor.
After the Japanese surrender in 1945, the CCP continued to use the National Revolutionary Army unit structures, until the decision was made in February 1947 to merge the Eighth Route Army and New Fourth Army. On October 10, 1947, the "Manifesto of the Chinese People's Liberation Army" was published, renaming the new million-strong force the People's Liberation Army (PLA). The reorganization was completed by late 1948. The PLA eventually won the Chinese Civil War, establishing the People's Republic of China in 1949.
== Pseudo-alkali metals == Many other substances are similar to the alkali metals in their tendency to form monopositive cations. Analogously to the pseudohalogens, they have sometimes been called "pseudo-alkali metals". These substances include some elements and many more polyatomic ions; the polyatomic ions are especially similar to the alkali metals in their large size and weak polarising power.
Sources: en.wikipedia.org
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.
It has not received marketing approval as a medicine in the United States or the European Union. Supplied material is generally described and handled as a research chemical. Regulatory treatment varies by jurisdiction, and some countries restrict growth hormone secretagogues under sports or medicines legislation.
Earlier secretagogues were associated with broader hormonal responses, including measurable changes in cortisol and prolactin. Reports on this peptide describe a narrower profile in which growth hormone release is the most prominent effect. The observation is influential because it shapes how the compound is compared with other members of the same receptor family.
Ipamorelin is a synthetic pentapeptide that stimulates growth hormone release by activating the ghrelin receptor. It is handled as a research tool rather than as a licensed therapeutic product. Its short chain length makes it comparatively simple to synthesize and analyze.