This is a working overview of 胃饥饿素受体, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-08. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
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。
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.
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.
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.
Mixed ligand complexes are common for amino acids. Well known examples include [Co(en)2(glycinate)]2+, where en (ethylenediamine) is a spectator ligand. In the area of organometallic complexes, one example is the half-sandwich complex Cp*Ir(κ3-methionine).
Recent theoretical developments in noble gas chemistry, in which helium is expected to show slightly less inertness than neon and to form (HeO)(LiF)2 with a structure similar to the analogous beryllium compound (but with no expected neon analogue), have resulted in more chemists advocating a placement of helium in group 2. This relates to the electronic argument, as the reason for neon's greater inertness is repulsion from its filled p-shell that helium lacks, though realistically it is unlikely that helium-containing molecules will be stable outside extreme low-temperature conditions (around 10 K). The first-row anomaly in the periodic table has additionally been cited to support moving helium to group 2. It arises because the first orbital of any type is unusually small, since unlike its higher analogues, it does not experience interelectronic repulsion from a smaller orbital of the same type. This makes the first row of elements in each block have unusually small atoms, and such elements tend to exhibit characteristic kinds of anomalies for their group. Some chemists arguing for the repositioning of helium have pointed out that helium exhibits similar anomalies if it is placed in group 2, but not if it is placed in group 18: on the other hand, neon, which would be the first group 18 element if helium was removed from that spot, does exhibit similar anomalies. The relationship between helium and beryllium is then argued to resemble that between hydrogen and lithium, a placement which is much more commonly accepted.
There are innumerable types of artifacts present in museum collections that include or are composed of human remains, some with great scientific or medical merit and others with great cultural importance. Not only do the body parts vary greatly, but so do their methods of preservation.
== Prognosis == Most patients with benign insulinomas can be cured with surgery. Persistent or recurrent hypoglycemia after surgery tends to occur in patients with multiple tumours. About 2% of patients develop diabetes mellitus after their surgery.
=== Early sexual differentiation === Placental progesterone can be converted into 5α-dihydrotestosterone (DHT), a potent androgen that is responsible for the development of male genitalia. This can be done both by conversion into testosterone, which is then converted to DHT, and via the androgen backdoor pathway, which is particularly important for fetal development. Progesterone is the precursor for both pathways and therefore contributes to sexual differentiation.
Sources: en.wikipedia.org
== Adverse effects == In clinical trials, the most common adverse effects of sildenafil use included headache, flushing, indigestion, nasal congestion, and impaired vision, including photophobia and blurred vision. Some sildenafil users have complained of seeing everything tinted blue (cyanopsia). This cyanopsia can be explained because sildenafil, while selective for PDE5, does have some affinity for PDE6, which is the phosphodiesterase found in the retina. Patients thus taking the drug may experience colorvision abnormalities. Some complained of blurriness and loss of peripheral vision. In July 2005, the US Food and Drug Administration (FDA) updated labeling for tadalafil (Cialis), vardenafil (Levitra), and sildenafil (Viagra) to reflect a small number of post-marketing reports of sudden vision loss, while acknowledging that "...it is not possible to determine whether these oral medicines for erectile dysfunction were the cause of the loss of eyesight or whether the problem is related to other factors such as high blood pressure or diabetes, or to a combination of these problems." A careful review of pooled data from clinical trials containing well documented information about the dose and duration of exposure to the drug for a large number of patients, yields no evidence for an increased risk of non-arteritic anterior ischemic optic neuropathy or other adverse ocular events associated with PDE5 inhibitor use.
The two substrates of this enzyme are epipregnanolone and oxidised nicotinamide adenine dinucleotide phosphate (NADP+). Its products are 5β-dihydroprogesterone, reduced NADPH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3beta-hydroxy-5beta-steroid:NADP+ 3-oxidoreductase. Other names in common use include 3beta-hydroxysteroid 5beta-oxidoreductase, and 3beta-hydroxysteroid 5beta-progesterone oxidoreductase.
== Further reading == Almond, Mark (2002). Uprising!: Ideological Shifts and Political Upheavals That Have Shaped the World. London: Octopus Publishing Group. ISBN 978-0-7607-3348-6. Garton Ash, Timothy (1990). The magic lantern: the revolution of '89 witnessed in Warsaw, Budapest, Berlin, and Prague. New York: Random House. ISBN 978-0-394-58884-1. Deletant, Dennis (1999). Romania under communist rule. Iasi: The Center for Romanian Studies. ISBN 978-973-98392-8-0. Gives a detailed account of the events in December 1989 in Timișoara. Engel, Jeffrey A. (2017). When the world seemed new: George H.W. Bush and the end of the Cold War. Boston; New York: Houghton Mifflin Harcourt. ISBN 978-0-547-42306-7. Ștefănescu, Domnița (1995). Cinci ani din istoria Romaniei: o cronologie a evenimentelor (decembrie 1989-decembrie 1994) [Five years of Romanian history: a chronology of events (December 1989-December 1994)] (in Romanian). Bucharest: Mașina de Scris. ISBN 978-9-73-971622-2. OCLC 909545436.
In addition, various organic acids can be biotechnologically produced from glucose, for example by fermentation with Clostridium thermoaceticum to produce acetic acid, with Penicillium notatum for the production of araboascorbic acid, with Rhizopus delemar for the production of fumaric acid, with Aspergillus niger for the production of gluconic acid, with Candida brumptii to produce isocitric acid, with Aspergillus terreus for the production of itaconic acid, with Pseudomonas fluorescens for the production of 2-ketogluconic acid, with Gluconobacter suboxydans for the production of 5-ketogluconic acid, with Aspergillus oryzae for the production of kojic acid, with Lactobacillus delbrueckii for the production of lactic acid, with Lactobacillus brevis for the production of malic acid, with Propionibacter shermanii for the production of propionic acid, with Pseudomonas aeruginosa for the production of pyruvic acid and with Gluconobacter suboxydans for the production of tartaric acid. Potent, bioactive natural products like triptolide that inhibit mammalian transcription via inhibition of the XPB subunit of the general transcription factor TFIIH has been recently reported as a glucose conjugate for targeting hypoxic cancer cells with increased glucose transporter expression. Recently, glucose has been gaining commercial use as a key component of "kits" containing lactic acid and insulin intended to induce hypoglycemia and hyperlactatemia to combat different cancers and infections.
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.
Dry powder is typically kept frozen, desiccated, and protected from light. Avoiding moisture exposure and large temperature swings helps slow degradation. Storage recommendations vary by supplier and should be followed for the specific material.