五肽 raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-08-08 and is reviewed periodically as new material appears.
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 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.
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。
| 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 |
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.
Reversed-phase high-performance liquid chromatography is the standard method for purity assessment, most often on a C18 column with a water and acetonitrile gradient and trifluoroacetic acid or formic acid as an ion-pairing agent. Mass spectrometry by electrospray or matrix-assisted laser desorption confirms the expected mass and reveals truncated or modified sequences. Amino acid analysis and sequencing provide orthogonal structural evidence. Typical impurities include deletion sequences, oxidized products, and dimeric species. Detection wavelength, usually 214 or 220 nanometers, should be reported because response factors differ between peptides.
Purity is normally reported as a percentage of total peak area, a figure that does not account for water content, residual solvents, or counterions. Trifluoroacetate and acetate are the most frequent counterions in lyophilized peptides, and they shift the true peptide content away from the mass of the powder. A separate quantitative assay is therefore needed to state content accurately. Certificates of analysis often omit these details, which makes batch-to-batch comparison difficult and limits conclusions drawn when results from different suppliers are compared.
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.
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.
At the cellular level, ipamorelin binds the growth hormone secretagogue receptor, also called the ghrelin receptor. Activation of this receptor on pituitary somatotroph cells triggers a signaling cascade that leads to release of growth hormone into circulation. Because release follows a pulsatile pattern, studies often report peak concentration and total area under the curve rather than a single time point. Selectivity for this receptor is the property most frequently discussed in comparative work.
Compared with older secretagogues such as hexarelin or GHRP-6, ipamorelin shows weaker stimulation of cortisol, prolactin, and appetite in the animal models used for early characterization. Whether that selectivity is preserved across longer human exposures remains an open question, because published clinical data are limited in size and duration. Reported effects on food intake are generally described as modest. The compound is therefore treated in the literature as a relatively selective research tool rather than a fully characterized therapeutic agent.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Researchers at a pharmaceutical company first described it in the 1990s while screening small peptides for growth hormone releasing activity. Its chain contains five amino acid residues, two of which are non-natural building blocks, including 2-aminoisobutyric acid and a naphthylalanine derivative. The molecule was designed to act at the ghrelin receptor while avoiding several effects observed with earlier secretagogues.
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.
=== Hepatocellular carcinoma === Hepatocellular carcinoma is the most common primary liver cancer, and the most common cause of death in people with cirrhosis. Screening using an ultrasound with or without cancer markers such as alpha-fetoprotein can detect this cancer and is often carried out for early signs which has been shown to improve outcomes.
Inhibition of fertilization by administration of progesterone during the luteal phase was also demonstrated in animals between 1947 and 1949. Ovulation inhibition by progesterone in animals was subsequently re-confirmed and expanded on by Gregory Pincus and colleagues in 1953 and 1954. Findings on inhibition of ovulation by progesterone in women were first presented at the Fifth International Conference on Planned Parenthood in Tokyo, Japan in October 1955. Three different research groups presented their findings on this topic at the conference. They included Pincus (in conjunction with John Rock, who did not attend the conference); a nine-member Japanese group led by Masaomi Ishikawa; and the two-member team of Abraham Stone and Herbert Kupperman. The conference marked the beginning of a new era in the history of birth control. The results were subsequently published in scientific journals in 1956 in the case of Pincus and in 1957 in the case of Ishikawa and colleagues. Rock and Pincus also subsequently described findings from 1952 that "pseudopregnancy" therapy with a combination of high doses of diethylstilbestrol and oral progesterone prevented ovulation and pregnancy in women. Unfortunately, the use of oral progesterone as a hormonal contraceptive was plagued by problems. These included the large and by extension expensive doses required, incomplete inhibition of ovulation even at high doses, and a frequent incidence of breakthrough bleeding.
=== Peptide nucleic acids (PNA) === Peptide nucleic acids are synthetic oligonucleotides that resist protease degradation and are used to induce repair at site-specific triplex formation regions on DNA genomic sites. PNAs are able to bind with high affinity and sequence specificity to a complementary DNA sequence through Watson-Crick base-pairing and are able to form triple helices through parallel orientation Hoogsteen bonds, with the PNA facing the 5'-end of the DNA strand. The PNA-DNA triplex is stable because PNAs consist of a neutrally charged pseudopeptide backbone which binds to the double stranded DNA (dsDNA) sequence. Similar to homopyrimidine in TFOs, homopyrimidine in PNAs is able to form a bond with the complementary homopurine in the target sequence of dsDNA. These DNA analogues are able to bind to dsDNA by exploiting ambient DNA conditions and different predicting modes of recognition. This is different from TFOs which bind though the major groove recognition of the dsDNA. One of the predicting modes of recognition used for recognition is through a duplex invasion. Within mixed A–T/G–C dsDNA sequence is targeted by a pair of pseudo-complementary (pc) PNAs which are able to bind to dsDNAs via double invasion through the simultaneous formation of diaminopurine (D) and thiouracil (Us) which substitute for adenine and thymine, respectively. The pc PNA pair form a D-T and Us -A and G-C or C-G Watson-Crick paired PNA-DNA helix with each of complementary DNA strands.
The term "percent homology" is often used to mean "sequence similarity", that is the percentage of identical residues (percent identity), or the percentage of residues conserved with similar physicochemical properties (percent similarity), e.g. leucine and isoleucine, is usually used to "quantify the homology." Based on the definition of homology specified above this terminology is incorrect since sequence similarity is the observation, homology is the conclusion. The term "percent homology" is a misnomer; sequences are either homologous or not. As with morphological and anatomical structures, sequence similarity might occur because of convergent evolution, or, as with shorter sequences, by chance, meaning that they are not homologous. Homologous sequence regions are also called conserved. This is not to be confused with conservation in amino acid sequences, where the amino acid at a specific position has been substituted with a different one that has functionally equivalent physicochemical properties. Partial homology can occur where a segment of the compared sequences has a shared origin, while the rest does not. Such partial homology may result from a gene fusion event.
== Matching gunshot residue to a specific source == If the ammunition used was specifically tagged in some way by special elements, it is possible to know the cartridge used to produce the gunshot residue. Inference about the source of gunshot residue can be based on the examination of the particles found on a suspect and the population of particles found on the victim, in the firearm or in the cartridge case, as suggested by the ASTM Standard Guide for gunshot residue analysis by scanning electron microscopy/energy dispersive X-ray spectrometry. Advanced analytical techniques such as ion beam analysis (IBA), carried out after scanning electron microscopy, can support further information allowing one to infer about the source of gunshot residue particles. Christopher et al. showed as the grouping behaviour of different makes of ammunition can be determined using multivariate analysis. Bullets can be matched back to a gun using comparative ballistics.
Sources: en.wikipedia.org
extracellular matrix (ECM) Also intercellular matrix. The network of interacting macromolecules and minerals secreted by and existing outside of and between cells in multicellular structures such as tissues and biofilms, forming a hydrated, mesh-like, semi-solid suspension which not only holds the cells together in an organized fashion but also provides structural and biochemical support, acting as an elastic, compressible buffer against external stresses as well as both regulating and influencing numerous aspects of cell behavior, among them cell adhesion, motility, metabolism, division, and cell-to-cell communication. The composition and properties of the ECM vary enormously between organisms and tissue types, but generally it takes the form of a polysaccharide gel in which various fibrous proteins (especially collagen and elastin), enzymes, and glycoproteins are embedded. Cells themselves both produce the matrix components and respond constantly to local matrix composition, a source of environmental feedback which is critical for differentiation, tissue organization, and development.
Ehrenfreund et al. (2001) found that amino acids in CI chondrites Ivuna and Orgueil were present at much lower concentrations than in CM chondrites (~30%), and that they had a distinct composition high in β-alanine, glycine, γ-ABA, and β-ABA but low in α-aminoisobutyric acid (AIB) and isovaline. This implies that they had formed by a different synthetic pathway, and on a different parent body from the CM chondrites.
=== Views on Brexit and involvement in the campaign for a People's Vote === He described the 2016 Brexit referendum result to leave the European Union as "the greatest constitutional crisis of modern times" and condemned Leave campaigner Boris Johnson as a coward for pulling out of the Conservative leadership election after winning the referendum, likening him to "a general who has led his troops to the sound of guns, and, at first sight of battle, has left the field." Lord Heseltine queried the way Theresa May as home secretary campaigned to remain in the EU though "within a few weeks" of becoming PM, she insisted "Brexit means Brexit". Heseltine mentioned a speech by Theresa May before the EU referendum, where she urged Britain to "stand tall and lead in Europe". Heseltine said: "I don't know how someone who made that speech can, within a few weeks, say Brexit is Brexit and ask the nation to unite behind it...[unlike Margaret Thatcher] this lady was for turning." In March 2017 he was sacked from a number of advisory roles within government after rebelling over the article 50 legislation in the House of Lords, but said he would continue working to avert the "disaster" of Brexit. He later said that it was "quite unacceptable" for Germany to be in dominant position in Europe, having lost the Second World War. Heseltine feels the 48% of British voters who voted 'remain' are being ignored. He sees Brexit as a historic loss of power for Britain and feels Britain's interests are in Europe.
== Further reading == Lamarck, J.B.P.; De Monet, Comte De (1815) [1814]. "Suite des polypiers empâtés". Mémoires du Muséum d'Histoire Naturelle. 1: 69–80, 162–168, 331–340. Hooper, J.N.A.; Wiedenmayer, F. (1994). "Porifera". In Wells, A. (ed.). Zoological Catalogue of Australia. Vol. 12. pp. 1–620.
A football pitch, or field, can be used as a man-in-the-street unit of area. The standard FIFA football pitch for international matches is 105 m (344 ft) long by 68 m (223 ft) wide (7,140 m2 or 0.714 ha or 1.76 acres); FIFA allows for a variance of up to 5 m (16.4 ft) in length in either direction and 7 m (23.0 ft) more or 4 m (13.1 ft) less in width (and larger departures if the pitch is not used for international competition), which generally results in the association football pitch generally only being used for order of magnitude comparisons. An American football field, including both end zones, is 360 by 160 ft (120.0 by 53.3 yd; 109.7 by 48.8 m), or 57,600 square feet (5,350 m2) (0.535 hectares or 1.32 acres). A Canadian football field is 65 yards (59 m) wide and 110 yards (100 m) long with end zones adding a combined 40 yards (37 m) to the length, making it 87,750 square feet (8,152 m2) or 0.8215 ha (2.030 acres). An Australian rules football field may be approximately 150 metres (160 yd) (or more) long goal to goal and 135 metres (148 yd) (or more) wide, although the field's elliptical nature reduces its area to a certain extent. A 150-by-135-metre (164 by 148 yd) football field has an area of approximately 15,900 m2 (1.59 ha; 3.9 acres), twice the area of a Canadian football field and three times that of an American football field.
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.
不是。它属于人工合成的五肽，设计上模拟胃饥饿素受体的部分作用，但不存在于人体天然激素谱中。