This is a working overview of ghrelin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-25 and is reviewed periodically as new material appears.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Reported for the free peptide |
| Molecular mass | 711.85 Da | Monoisotopic value |
| Residue motif | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Non-natural residues at positions one and three |
| Primary target | GHSR-1a | Ghrelin receptor, G protein coupled |
| Reported plasma half-life | About two hours | Values vary with assay and subject group |
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。
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.
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.
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.
Purity assessment for this peptide relies mainly on reversed-phase high-performance liquid chromatography. A C18 column with a water-acetonitrile gradient containing trifluoroacetic acid separates the target from truncated sequences and oxidation products. Detection near 214 nm exploits the amide backbone, while the aromatic side chains allow additional monitoring close to 280 nm. Reported purity values depend on the method, so a certificate of analysis carries weight only when gradient, column and integration parameters are given.
Mass spectrometry confirms identity and reveals structural deviations that chromatography alone can miss. Positive-mode electrospray ionisation generally yields multiply charged ions whose deconvoluted mass is checked against the theoretical value. Amino acid analysis, and enzymatic digestion with subsequent fragment mapping, provide independent confirmation of sequence and of the terminal amide. Analysts take care to separate the target from deletion sequences, which may differ by one residue and therefore by only a small mass increment.
=== Electronic Submissions Gateway (ESG) === To standardize, automate and streamline the flow of regulatory data, FDA introduced an Electronic Submissions Gateway (ESG) in 2006. This gateway allows reporting organizations to send regulatory submissions to different centers over the internet, packaged in a center-specific format and enveloped as a GNU-compatible .tar.gz file, through either a FDA-specific WebTrader application or via a more generic B2B communication protocol called AS2 (Applicability Statement 2).
=== False eggs === Calculus: Calculi are egg-like objects formed in the stomachs of ruminants such as cattle, deer, elk, and goats. Calculus formation is a defense mechanism protecting the ruminant's stomach from damage if it swallows a foreign object while grazing. After ingestion, the object is covered by the same material composing bone, calcium phosphate, and eventually vomited out of the animal's system. These "stomach stones" tend to range in size from 1 to 6 centimeters. Larger sizes are known but very rare. Sometimes tiny dimples cover the surface of a stomach stone, which can fool observers into thinking they are the pores of an egg. Fossil egg expert Ken Carpenter has described stomach stones as the most egg-like natural objects, noting that they are "the trickiest [egg-like] objects to correctly identify". Calculi are so egg-like that on one occasion a detailed description of a stomach stone misidentified as a fossil egg was published in the scientific literature. Calculi can be distinguished from real egg fossils because when they are broken open, they show the layers of calcium phosphate and the foreign object at the core. Multiple layers of eggshell are known in pathological eggs, but these layers don't go all the way down to its core the way a stomach stone's do. Calculi are often suspiciously intact, unlike fossil eggs, which are usually damaged. Stomach stones also lack distinct shells with their attending structural components like continuous or prismatic layers, mammillae, and pores.
5-HT2, 5-HT6, 5-HT7: antipsychotic effects, sedation/anxiolysis, antidepressant effect, weight gain D1, D2, D3, D4, D5: antipsychotic effects, sedation, extrapyramidal side effects, prolactin increase, depression, apathy/anhedonia, weight gain H1: sedation, weight gain Muscarinic acetylcholine receptors: anticholinergic effects, inhibition of extrapyramidal side effects α1-Adrenergic: hypotension, sedation, anxiolysis Because of its potent serotonin 5-HT2A and muscarinic acetylcholine receptor antagonism, chlorprothixene causes relatively mild extrapyramidal symptoms. This is in contrast to most other typical antipsychotics. For this reason, chlorprothixene has sometimes been described instead as an atypical antipsychotic. Chlorprothixene has also been found to act as FIASMA (functional inhibitor of acid sphingomyelinase).
Bakker sold colloidal silver supplements that he advertised as a panacea. In March 2020, the office of the Attorney General of New York ordered Bakker to cease making false medicinal claims about his supplements' alleged ability to cure the 2019–2020 strains of coronavirus, and the Federal Trade Commission and the Food and Drug Administration also sent a warning letter to Bakker about his claims regarding the supplements and coronavirus. Missouri attorney general Eric Schmitt and Arkansas attorney general Leslie Rutledge filed lawsuits against Bakker for allegedly pushing the supplements as a treatment for the virus. In the State lawsuit against him, Bakker is represented by former Missouri governor Jay Nixon, who has argued for the suit to be dismissed. Nixon says that the allegations made in the lawsuit are false, stating: "Bakker is being unfairly targeted by those who want to crush his ministry and force his Christian television program off the air." In April 2020, prohibited from receiving credit card transactions, Bakker disclosed to his viewers that his ministry was on the brink of filing for bankruptcy and urgently petitioned them for donations. The following month, GEB America and World Harvest Television dropped Bakker's program from their networks after DirecTV owner AT&T asked channels to reconsider airing the show. AT&T made the request of its channels in response to a deplatforming campaign from the liberal Christian group Faithful America. On May 8, 2020, Lori Bakker announced that Jim Bakker had suffered a stroke that his son Jay described as "minor".
If it is important to have a uniform distribution of incubation times for the droplets, the delay line channel may contain regularly spaced constrictions. Droplets flowing through a channel of uniform diameter travel at different speeds based on their radial position; droplets closer to the center of the channel move faster than those near the edges. By narrowing the channel width to a fraction of its original size, droplets with higher velocities are forced to equilibrate with slower-moving droplets because the constriction allows fewer droplets to pass through at a time. Another manipulation to the geometry of the delay line channel involves introducing turns to the droplets' trajectory. This increases the extent to which any reagents contained within the droplets are mixed via chaotic advection. For systems requiring the incubation of 100 to 1000 droplets, traps can be fabricated in the delay line channel that store droplets separately from one another. This provides for finer control and monitoring of individual droplets.
Sources: en.wikipedia.org
The severity of chronic kidney disease (CKD) is described by six stages; the most severe three are defined by the MDRD-eGFR value, and first three also depend on whether there is other evidence of kidney disease (e.g., proteinuria):
== Environmental record == According to the 2022 "Top 100 Polluters Indexes" published by the University of Massachusetts, Amherst's "Political Economy Research Institute" (PERI), BASF was ranked the #2 largest polluter of air and #14 largest polluter of water in 2020, the most recent year for which data is available from the U.S. Environmental Protection Agency. In 2006, BASF was included in the Climate Leadership Index for their efforts in relation to climate change and greenhouse gas emissions. The BASF Company and Columbia University formed a partnership to further research "environmentally benign and sustainable energy sources". The company has recently reported their emissions in 2006 to be "1.50 million metric tons of waste," which is a decrease from previous years. The amount of waste BASF produces has continued to fall. While BASF publishes its environmental information in the US and Europe, Greenpeace has expressed deep concerns at BASF's refusal to release environmental information on its operations in China. In May 2009, a BASF Plant in Hannibal, Missouri, United States, accidentally discharged chromium into the Mississippi River. The local Department of Natural Resources performed tests in December 2009 showing the chromium levels did not exceed regulatory safety limits. BASF worked with the Missouri Department of Natural Resources (MoDNR) to resolve questions regarding the elevated level of hexavalent chromium that was detected in the effluent from one of its permitted outfalls into the Mississippi River.
== Oxidants and reductants == Oxidizing agents are added to flour to help with gluten development. They may or may not also act as bleaching agents. Originally flour was naturally aged through exposure to the atmosphere. Oxidizing agents primarily affect sulfur-containing amino acids, ultimately helping to form disulfide bridges between the gluten molecules. The addition of these agents to flour will create a stronger dough. Dehydroascorbic acid and potassium bromate are oxidants, acting on sulfhydryl groups and disulfide bonds in wheat dough, in particular oxidizing glutathione. Potassium bromate acts more directly or with fewer chemical conversion steps than ascorbic acid. Glutathione increases wheat dough's extensibility, or relaxes it, while oxidizing a dough's glutathione increases elasticity. Common oxidizing agents are:
==== Binge eating disorder ==== Binge eating disorder (BED) is characterized by recurrent and persistent episodes of compulsive binge eating. These episodes are often accompanied by marked distress and a feeling of loss of control over eating. The pathophysiology of BED is not fully understood, but it is believed to involve dysfunctional dopaminergic reward circuitry along the cortico-striatal-thalamic-cortical loop. As of July 2024, lisdexamfetamine is the only USFDA- and TGA-approved pharmacotherapy for BED. Evidence suggests that lisdexamfetamine's treatment efficacy in BED is underpinned at least in part by a psychopathological overlap between BED and ADHD, with the latter conceptualized as a cognitive control disorder that also benefits from treatment with lisdexamfetamine. Lisdexamfetamine's therapeutic effects for BED primarily involve direct action in the central nervous system after conversion to its pharmacologically active metabolite, dextroamphetamine. Dextroamphetamine increases dopaminergic and noradrenergic neurotransmission in prefrontal cortex, a region of the brain that regulates cognitive control of behavior. Similar to its therapeutic effect in ADHD, dextroamphetamine enhances cognitive control and may reduce impulsivity in patients with BED by enhancing the cognitive processes responsible for overriding prepotent feeding responses that precede binge eating episodes.
Sources: en.wikipedia.org
=== Instrumentation and lyrics === Jerry Cantrell's guitar style combines "pummeling riffs and expansive guitar textures" to create "slow, brooding minor-key grinds". He is also recognized for his natural ability to blend acoustic and electric guitars. While down-tuned, distorted guitars mixed with Staley's distinctive "snarl-to-a-scream" vocals appealed to heavy metal fans, the band also had "a sense of melody that was undeniable," which introduced Alice in Chains to a much wider audience outside of the heavy metal underground. According to Stephen Thomas Erlewine of AllMusic, Alice in Chains' sound has a "Black Sabbath-style riffing and an unconventional vocal style." The band has been described by Erlewine as "hard enough for metal fans, yet their dark subject matter and punky attack placed them among the front ranks of the Seattle-based grunge bands." Three of the band's releases feature acoustic music, and while the band initially kept these releases separate, Alice in Chains' self-titled album combined the styles to form "a bleak, nihilistic sound that balanced grinding hard rock with subtly textured acoustic numbers." Alice in Chains is also noted for the unique vocal harmonies of Staley (or DuVall) and Cantrell, which included overlapping passages, dual lead vocals, and trademark harmonies typically separated by a major third. Cantrell said it was Staley who gave him the self-assurance to sing his own songs.
In the 1970s, biscuit manufacturers began using micro-aeration to process chocolate for moulded products. This was a cost-saving measure: with less chocolate, the same volume of coated biscuit could be maintained. In 1981 or 1983, Cadbury released Wispa, an aerated chocolate with a more chunky shape than Aero bars, made using a secret, non-patented process. The launch of Wispa was successful, but it soon encountered manufacturing difficulties and was temporarily withdrawn from the market. While Wispa was off the market, Rowntree's developed and launched a chunky Aero which they successfully launched and was still being sold as of 2008. Wispa was discontinued in the early 2000s so Cadbury could bring in a new aerated chocolate product aligned with the Cadbury Dairy Milk brand: Dairy Milk Bubbly. Following an internet campaign in 2007, Cadbury reintroduced Wispa. Today, Aero is manufactured by Nestlé, the brand having been acquired by Nestlé during a 1988 takeover of Rowntree's. As of 2023, other brands of aerated chocolate includes Mirage and Galaxy.
== Before Tiselius == Early work with the basic principle of electrophoresis dates to the early 19th century. The electrokinetic phenomenon was observed for the first time in 1807 by Russian professors Peter Ivanovich Strakhov and Ferdinand Frederic Reuß at Moscow University, who noticed that the application of a constant electric field caused clay particles dispersed in water to migrate. Experiments by Johann Wilhelm Hittorf, Walther Nernst, and Friedrich Kohlrausch to measure the properties and behavior of small ions moving through aqueous solutions under the influence of an electric field led to general mathematical descriptions of the electrochemistry of aqueous solutions. Kohlrausch created equations for varying concentrations of charged particles moving through solution, including sharp moving boundaries of migrating particles. By the beginning of the 20th century, electrochemists had found that such moving boundaries of charged particles could be created with U-shaped glass tubes. Methods of optical detection of moving boundaries in liquids had been developed by August Toepler in the 1860s; Toepler measured the schlieren (shadows) or slight variations in optical properties in inhomogeneous solutions. This method combined with the theoretical and experimental methods for creating and analysing charged moving boundaries would form the basis of Tiselius' moving-boundary electrophoresis method.
Sources: en.wikipedia.org
Both molecules activate the same receptor, GHSR-1a, but they share little sequence identity. Ghrelin is a 28-amino-acid hormone carrying a distinctive acyl modification, whereas ipamorelin is a short synthetic peptide. The shared target explains overlapping endocrine effects, while the different structures account for differences in metabolic stability and receptor selectivity.
Early animal and human studies reported growth hormone release at levels that produced small changes in cortisol, prolactin and adrenocorticotropic hormone. That contrast with older secretagogues gave rise to the selectivity label. The observation is consistent across several reports but rests on a limited number of small studies.
Plasma peptidases cleave the molecule into smaller fragments, and reported half-lives in human studies are on the order of a couple of hours. The identity and activity of individual breakdown products have not been fully mapped. Questions about tissue-level clearance remain open.
Reversed-phase liquid chromatography is standard for purity, and mass spectrometry is standard for identity. Amino acid analysis is used when quantitative composition matters. No single technique answers every question, so laboratories usually combine two or three.