A practical reference on 五肽: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-05. Anything still debated is marked as such rather than presented as settled.
Activity is mediated mainly through the growth hormone secretagogue receptor, now generally called the ghrelin receptor or GHS-R1a. Binding at this G-protein-coupled receptor triggers phospholipase C signaling, calcium mobilization, and release of growth hormone from pituitary somatotrophs. Reports describe less pronounced stimulation of adrenocorticotropic hormone and prolactin compared with earlier secretagogues such as hexarelin or GHRP-6. Selectivity figures vary between assay systems, so the degree of separation from other secretagogues is an area of ongoing comparison rather than a fixed constant.
In animal and early human studies, ipamorelin produces pulsatile growth hormone release and a secondary rise in insulin-like growth factor 1. The magnitude and duration of that rise depend on route, sampling schedule, and the baseline endocrine state of the subject. Whether repeated exposure alters the response over time is not firmly settled, since some reports describe stable pulsatility while others note attenuation. Most published data come from small samples, which limits the strength of any general claim about long-term behavior.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, a structure that differs from natural ghrelin in length and in the presence of non-natural amino acid residues. Early laboratory work described it as a comparatively selective agent that stimulates growth hormone release with limited effect on other pituitary hormones. The compound is supplied as a lyophilized solid for research use and has no identified natural source in the body.
Most published work on ipamorelin comes from rodent studies and small early-phase human trials. Subcutaneous and intravenous routes have been used, while oral delivery is limited by poor absorption and rapid breakdown in the gut. The reported plasma half-life is short, on the order of two hours, and varies with species and assay method. Whether chronic use produces meaningful clinical benefit remains unresolved, and long-term safety data in humans are sparse. No major regulatory agency has approved the compound as a therapeutic drug.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic pentapeptide | GHS-R1a agonist family |
| Receptor target | Ghrelin receptor (GHS-R1a) | G-protein-coupled receptor |
| Sequence length | Five amino acid residues | Includes non-natural residues |
| Primary reported output | Pulsatile growth hormone release | Observed in animal and early human work |
| Molecular formula | C38H49N9O5 | Corresponds to roughly 711.9 g/mol |
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。
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。
Identity and purity are assessed by complementary methods rather than a single test. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and reports a percentage purity. Mass spectrometry, most often with electrospray ionization, confirms the expected molecular mass and detects sequence-related variants. Amino acid analysis can verify composition, while water content and residual counterion measurements support the mass balance of a batch. Stability studies under accelerated conditions are used to estimate shelf life, though such estimates carry uncertainty for long-term storage.
Material supplied for research use is normally a white to off-white lyophilized powder. The solid is hygroscopic and is handled in a low-humidity environment to limit water uptake. Bulk quantities are frequently shipped in sealed vials under inert gas. Once reconstituted in water or a neutral buffer, the solution is less stable than the dry powder and is usually divided into single-use aliquots.
Long-term storage of the dry powder is typically at minus twenty degrees Celsius or lower, protected from light and moisture. Solutions are commonly kept frozen and thawed only once, because repeated freeze-thaw cycles can promote aggregation and loss of measurable peptide content. Buffers near neutral pH are preferred over strongly acidic or strongly basic conditions. Shipping at ambient temperature is acceptable for short periods when the powder remains sealed and desiccated.
Lyophilized material is generally stored frozen and protected from light and moisture. Typical recommendations place dry powder at temperatures well below freezing, while reconstituted solutions are kept cold and used within a defined window. Repeated freezing and thawing should be avoided because it can promote aggregation and loss of material. The choice of solvent matters as well; compatibility with the intended diluent should be checked before preparation. These handling practices aim to preserve both the quantity and the integrity of the peptide.
Verification of identity and purity relies on analytical methods used across peptide chemistry. Reverse-phase high-performance liquid chromatography separates components by hydrophobicity and provides a purity estimate. Mass spectrometry confirms molecular mass and helps detect modifications. Together these techniques give complementary information about whether a sample matches its expected structure. Results depend on method parameters and reference standards, so reported purity values are meaningful only when the analytical conditions are stated. Consistency between laboratories requires comparable protocols and well-characterized reference materials.
Peptides such as ipamorelin are subject to chemical and physical degradation. Hydrolysis of peptide bonds, oxidation of susceptible residues, and aggregation are common pathways that reduce purity over time. The rate of these processes depends on temperature, moisture, pH, and the number of freeze-thaw cycles a sample undergoes. Because the compound is typically handled as a lyophilized powder, controlling moisture during storage is a central concern. Degradation products can be detected with separation techniques that resolve the parent peptide from related impurities.
Research peptides such as ipamorelin are commonly supplied as lyophilized powder and characterized by analytical certificates. Reversed-phase high-performance liquid chromatography is used to estimate purity by ultraviolet absorbance, while mass spectrometry confirms molecular identity and detects sequence-related impurities. Counterion content, water content, and residual synthesis reagents can affect the reported mass balance. A certificate of analysis may list a purity percentage, but that number depends on the analytical method and the definition of impurity peaks. Independent verification is often recommended because research supply chains vary in quality control practices.
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.
== Control of expression == The malE gene, coding for MBP, belongs to the Mal regulon of E. coli, which consists of ten genes whose products are geared for the efficient uptake and utilization of maltose and maltodextrins. All the gene involved in the transport of maltose/maltodextrin, including malE, are clustered in the malB region of E. coli and organized in two divergent operons: malE-malF-malG and malK-lamB. The transcription start sites at the malEp and malKp promoters are distant of 271 base pairs. The malEp and malKp promoters are synergistically activated by protein MalT, the activator of the Mal regulon and by the cAMP receptor protein CRP. This activation is a coupled process that involves, going from malEp towards malKp: two MalT binding sites; three CRP binding sites, and two overlapping sets of three MalT binding sites, staggered by three base pairs. Transcription activation requires the binding of adenosine triphosphate (ATP) and maltotriose to MalT and the binding of cyclic AMP to the dimer of CRP. The unliganded form of MalT is monomeric whereas its liganded form, in the presence of ATP and maltotriose, is oligomeric.
== Prognosis == Quality of life is impacted severely and the prognosis of patients with Rabson–Mendenhall syndrome remains poor. This is due to the lack of a long-term treatment. Life expectancy is 1–2 years.
=== EC 1.12.98 With other known acceptors === EC 1.12.98.1: coenzyme F420 hydrogenase EC 1.12.98.2: 5,10-methenyltetrahydromethanopterin hydrogenase EC 1.12.98.3: Methanosarcina-phenazine hydrogenase EC 1.12.98.4: Sulfhydrogenase
== Etymology == The name "Colombia" is derived from the last name of the Italian navigator Christopher Columbus (Latin: Christophorus Columbus, Italian: Cristoforo Colombo, Spanish: Cristóbal Colón). It was conceived as a reference to all of the New World. The name was later adopted by the Republic of Colombia of 1819, formed from the territories of the old Viceroyalty of New Granada (modern-day Colombia, Panama, Venezuela, Ecuador, and northwest Brazil). When Venezuela, Ecuador, and Cundinamarca came to exist as independent states, the former Department of Cundinamarca adopted the name "Republic of New Granada". New Granada officially changed its name in 1858 to the Granadine Confederation. In 1863 the name was again changed, this time to United States of Colombia, before finally adopting its present name – the Republic of Colombia – in 1886. To refer to this country, the Colombian government uses the terms Colombia and República de Colombia.
First Minister of Wales Eluned Morgan is appointed a Privy Councillor. 29 August – Starmer confirms that the UK government is considering introducing tougher measures on outdoor smoking in order to reduce the number of tobacco-related deaths. Colum Eastwood announces he will resign as leader of the Social Democratic and Labour Party, triggering a leadership election. 30 August – A review is launched into Starmer's appointments of Labour donors to senior civil service jobs following allegations of cronyism. Conservative MP Esther McVey is criticised as "repugnant" by Jewish groups for sharing part of "First They Came", Martin Niemoller's 1946 poem about the Holocaust, in a tweet voicing her opposition to proposed new bans on outdoor smoking. McVey insists she was not equating the bans with Nazi persecution of the Jews, and says "no offence was ever intended". It is reported that Starmer has moved a portrait of Margaret Thatcher from her former 10 Downing Street study to elsewhere in the building. He subsequently says that he moved the portrait because he "didn’t want a picture of anyone" in his study and prefers landscapes. 2024 Ulster Unionist Party leadership election: After nominations close, Mike Nesbitt is the only candidate to put their name forward, and will be ratified as the party's next leader at a meeting on 14 September. During a closed-door session at the SNP Party Conference, leader John Swinney tells delegates the party's losses at the election occurred because it spent too much time focusing on the "process of independence".
Sources: en.wikipedia.org
The chemistry of plutonium was found to resemble uranium after a few months of initial study. Early research was continued at the secret Metallurgical Laboratory of the University of Chicago. On August 20, 1942, a trace quantity of this element was isolated and measured for the first time. About 50 micrograms of plutonium-239 combined with uranium and fission products was produced and only about 1 microgram was isolated. This procedure enabled chemists to determine the new element's atomic weight. On December 2, 1942, on a racket court under the west grandstand at the University of Chicago's Stagg Field, researchers headed by Enrico Fermi achieved the first self-sustaining chain reaction in a graphite and uranium pile known as CP-1. Using theoretical information garnered from the operation of CP-1, DuPont constructed an air-cooled experimental production reactor, known as X-10, and a pilot chemical separation facility at Oak Ridge. The separation facility, using methods developed by Glenn T. Seaborg and a team of researchers at the Met Lab, removed plutonium from uranium irradiated in the X-10 reactor. Information from CP-1 was also useful to Met Lab scientists designing the water-cooled plutonium production reactors for Hanford. Construction at the site began in mid-1943. In November 1943 some plutonium trifluoride was reduced to create the first sample of plutonium metal: a few micrograms of metallic beads. Enough plutonium was produced to make it the first synthetically made element to be visible with the unaided eye.
== 19th century: the emergence of biological disciplines == Up through the 19th century, the scope of biology was largely divided between medicine, which investigated questions of form and function (i.e., physiology), and natural history, which was concerned with the diversity of life and interactions among different forms of life and between life and non-life. By 1900, much of these domains overlapped, while natural history (and its counterpart natural philosophy) had largely given way to more specialized scientific disciplines—cytology, bacteriology, morphology, embryology, geography, and geology.
In 1982, Hafez al-Assad responded to an insurrection led by the Muslim Brotherhood in the city of Hama by sending paramilitary forces that indiscriminately killed between 40,000 and 55,000 civilians including children, women, and the elderly during the Hama massacre. State-violence perpetrated by Assad's reign have targeted women extensively, subjecting them to discrimination and gender-based violence. Between 1980 and 2000, more than 17,000 Syrian civilians were subjected to forced disappearance from the Ba'athist regime. During Baathist occupation of Lebanon, numerous Lebanese, Palestinian and other Arab civilians went missing. More than 35 torture techniques were reported to be employed in Syrian prisons and military detention centres during this time. A 1983 report published by Amnesty International revealed that Assad regime routinely committed mass-executions of alleged dissidents and engaged in the extensive torture of prisoners of conscience. Various torture methods in Syrian prisons include electrocutions, immolation, sexual violence, castration, etc. In 2000, Bashar al-Assad inherited the totalitarian system of Ba'athist Syria following the death of his father. His regime was characterized by even more systemic violence and repression than that of Hafez al-Assad. This has been widely attributed to Bashar's inexperience in security and political affairs, in addition to personal insecurities regarding the survival of his family regime.
B&K Corporation Limited (Traditional Chinese: 青城新藥生物科技（青島）股份有限公司, SEHK: 2396) is a China-based biopharmaceutical company founded in 2012 and headquartered in Qingdao. The company is engaged in the research, development and commercialisation of protein-based therapeutics, with a primary focus on platelet-derived growth factor (PDGF) drugs for wound healing indications. The joint sponsors of the offering were Huatai Financial Holdings (Hong Kong) and CITIC Securities (Hong Kong).
The Cold War was reflected in culture through music, movies, books, television, and other media, as well as sports, social beliefs, and behavior. Major elements of the Cold War included the perceived threat of communist expansion, a nuclear war, and – connected to both – espionage. Many works use the Cold War as a backdrop or directly take part in a fictional conflict between the United States and the Soviet Union and their respective allies. The period 1953–62 saw Cold War themes becoming mainstream as a public preoccupation.
Sources: en.wikipedia.org
Prolific in film since 1964, Freeman is known for his roles in genres ranging from dramas, historical epics, thrillers, action adventure, science fiction, and comedies. His most acclaimed and highest-grossing films, according to the review aggregate site Rotten Tomatoes, include the following:
GSK completed the acquisition of New Jersey–based Block Drug in 2001, for US$1.24 billion. In 2006, GSK acquired the US-based consumer healthcare company CNS Inc., whose products included Breathe Right nasal strips and FiberChoice dietary supplements, for US$566 million in cash. Chris Gent, previously CEO of Vodafone, was appointed chairman of the board in 2005. GSK opened its first R&D centre in China in 2007, in Shanghai, initially focused on neurodegenerative diseases. Andrew Witty became the chief executive officer in 2008. Witty joined Glaxo in 1985, and had been president of GSK's Pharmaceuticals Europe since 2003. In 2009, GSK acquired Stiefel Laboratories, then the world's largest independent dermatology drug company, for US$3.6 billion. In November 2009, the FDA approved GSK's vaccine for 2009 H1N1 influenza protection, manufactured by the company's ID Biomedical Corp in Canada. Also in November 2009, GSK formed a joint venture with Pfizer to create ViiV Healthcare, which specializes in HIV research. In 2010, the company acquired Laboratorios Phoenix, an Argentine pharmaceutical company, for US$253m, and the UK-based sports nutrition company Maxinutrition for £162 million (US$256 million).
The complete biosynthetic gene cluster for bottromycin has been identified. It is predicted to contain 13 genes, including the precursor peptide (notation will follow Crone and colleagues; other studies had similar results). One of the genes in the cluster, btmL, is proposed to be a transcriptional regulator. Another gene, btmA, is proposed to export bottromycin. The remaining ten genes are expected to modify the precursor peptide btmD from a linear peptide to the final macrocyclic product.
=== Regulation of epithelial-mesenchymal transition and metastasis === ITGA1 mediates communication between collagen-rich ECM environments ands transforming growth factor-β (TGFβ) signaling pathways. In pancreatic cancer, ITGA1 promotes TGFβ/collagen-induced epithelial-mesenchymal transition (EMT), which is distinguishable by decreased epithelial markers such as E-cadherin (CDH1) as well as increased mesenchymal markers such as FN1, ZEB1, VIM, and MUC1. Through these mechanisms, ITGA1 promotes cellular plasticity. This is associated with invasion and metastatic progression. ITGA1 is required for efficient metastatic dissemination of living PDAC cells. Loss of ITGA1 reduces tumor spread in experimental models, displaying ITGA1's contribution to metastatic behavior by enabling tumor cells to respond to collagen and TGFβ-rich micro-environments.
After menopause, the body produces less estrogen. This causes atrophic vaginitis (thinning and inflammation of the vaginal walls), which can lead to vaginal itching, burning, bleeding, soreness, or vaginal dryness (a decrease in lubrication). Vaginal dryness can cause discomfort on its own or discomfort or pain during sexual intercourse. Hot flashes are also characteristic of menopause. Menopause also affects the composition of vaginal support structures. The vascular structures become fewer with advancing age. Specific collagens become altered in composition and ratios. It is thought that the weakening of the support structures of the vagina is due to the physiological changes in this connective tissue. Menopausal symptoms can be eased by estrogen-containing vaginal creams, non-prescription, non-hormonal medications, vaginal estrogen rings such as the Femring, or other hormone replacement therapies, but there are risks (including adverse effects) associated with hormone replacement therapy. Vaginal creams and vaginal estrogen rings may not have the same risks as other hormone replacement treatments. Hormone replacement therapy can treat vaginal dryness, but a personal lubricant may be used to temporarily remedy vaginal dryness specifically for sexual intercourse. Some women have an increase in sexual desire following menopause. It may be that menopausal women who continue to engage in sexual activity regularly experience vaginal lubrication similar to levels in women who have not entered menopause, and can enjoy sexual intercourse fully.
Sources: en.wikipedia.org
It is a synthetic pentapeptide in the growth hormone secretagogue family and acts as an agonist at the ghrelin receptor. It is handled as a laboratory research compound rather than a naturally occurring hormone.
Studies generally report growth hormone as the dominant output, with smaller or absent effects on adrenocorticotropic hormone and prolactin. The size of that separation depends on the assay and the dose examined, so it is best described as relative selectivity.
No natural source has been identified, and the molecule is produced by chemical synthesis. Its non-natural residues distinguish it from endogenous ghrelin even though both engage the same receptor.
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.