The short version of 胃饥饿素受体 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-23 and is reviewed periodically as new material appears.
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。
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。
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.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C38H49N9O5 | 五肽，含非天然氨基酸残基 |
| 分子量 | 711.85 g/mol | 理论值，盐形式可能略有差异 |
| 外观 | 白色至类白色粉末 | 冻干粉常见 |
| 溶解性 | 易溶于水 | 也可溶于部分极性有机溶剂 |
| 储存条件 | -20°C，干燥避光 | 长期保存通常推荐 |
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.
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.
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.
The lungs are not capable of expanding to breathe on their own, and will only do so when there is an increase in the volume of the thoracic cavity. This is achieved by the muscles of respiration, through the contraction of the diaphragm, and the intercostal muscles which pull the rib cage upwards as shown in the diagram. During breathing out the muscles relax, returning the lungs to their resting position. At this point the lungs contain the functional residual capacity (FRC) of air, which, in the adult human, has a volume of about 2.5–3.0 litres. During heavy breathing as in exertion, a large number of accessory muscles in the neck and abdomen are recruited, that during exhalation pull the ribcage down, decreasing the volume of the thoracic cavity. The FRC is now decreased, but since the lungs cannot be emptied completely there is still about a litre of residual air left. Lung function testing is carried out to evaluate lung volumes and capacities.
The CDC reported that the prevalence of obesity among U.S. adults aged 20 and over was 41.9% from 2017 to March 2020, with severe obesity at 9.2% during the same period. Prevalence was lowest among non-Hispanic Asian adults (17.4%), compared with non-Hispanic white (42.2%), non-Hispanic Black (49.6%), and Hispanic (44.8%) adults.
== History == In the 1960s, Werner Bollag of Roche Laboratories began studying 13-cis retinoic acid as a treatment for skin cancer. By 1971, Roche showed that the compound was likely ineffective against cancer but useful for treating acne. However, Roche abandoned the product after finding a likelihood that the compound could cause birth defects, as the thalidomide scandal had raised the public's fear of such side effects. In 1975, Gary Peck, a dermatologist at the National Cancer Institute, initiated a collaboration with Hoffmann-La Roche to evaluate the efficacy of isotretinoin for a number dermatological conditions previously managed with retinoic acids, including acne, psoriasis, genetic skin disorders, and skin cancer prevention. After Peck authored an article in 1979 reporting the drug's effectiveness against cystic and conglobate acne, Roche submitted a New Drug Application to the Food and Drug Administration (FDA). While admitting that isotretinoin caused birth defects in rabbits, Roche avoided regulatory scrutiny by excluding pregnant women from its clinical trials and secured FDA approval in 1982. Despite prior correlation of isotretinoin with birth defects, Accutane quickly became the dominant acne treatment prescribed by dermatologists and general practitioners alike. In 1983, the FDA made the unprecedented decision to warn blood banks against accepting the blood of donors taking isotretinoin and instruct women to begin taking contraceptives one month before use.
== Medicical values == The plants have been known to possess various phytochemicals (secondary metabolites) which help them to protect themselves, these phytoehemicals since time immemorial have been used by humans for their medicinal needs. The microbes are developing resistant again multiple synthetic drugs, thus leading to the emergence of MDR (Multi Drug Resistant) strains of microbes, which pose a challenge to the modern drug system. To overcome this challenge, the nanoparticles synthesized using extracts of plant and plant parts have emerged as a hope. Many workers have reported that the nanoparticles synthesized using plant extracts have shown to exhibit enhanced medicinal properties as compared to the extract(s) alone.
Sources: en.wikipedia.org
Nicholas Kemmer of the Cambridge team independently proposed the same name, based on the same reasoning as the Berkeley team. Seaborg originally considered the name "plutium", but later thought that it did not sound as good as "plutonium". He chose the letters "Pu" as a joke, in reference to the interjection "P U" to indicate an especially disgusting smell, which passed without notice into the periodic table. Alternative names considered by Seaborg and others were "ultimium" or "extremium" because of the erroneous belief that they had found the last possible element on the periodic table. Hahn and Strassmann, and independently Kurt Starke, were at this point also working on transuranic elements in Berlin. It is likely that Hahn and Strassmann were aware that plutonium-239 should be fissile. However, they did not have a strong neutron source. Element 93 was reported by Hahn and Strassmann, as well as Starke, in 1942. Hahn's group did not pursue element 94, likely because they were discouraged by McMillan and Abelson's lack of success in isolating it when they had first found element 93. However, since Hahn's group had access to the stronger cyclotron at Paris at this point, they would likely have been able to detect plutonium had they tried, albeit in tiny quantities (a few becquerels).
As the microscopic world was expanding, the macroscopic world was shrinking. Botanists such as John Ray worked to incorporate the flood of newly discovered organisms shipped from across the globe into a coherent taxonomy, and a coherent theology (natural theology). Debate over another flood, the Noachian, catalyzed the development of paleontology; in 1669 Nicholas Steno published an essay on how the remains of living organisms could be trapped in layers of sediment and mineralized to produce fossils. Although Steno's ideas about fossilization were well known and much debated among natural philosophers, an organic origin for all fossils would not be accepted by all naturalists until the end of the 18th century due to philosophical and theological debate about issues such as the age of the earth and extinction.
Upon heating, Δ9-tetrahydrocannabinolic acid decarboxylates to give the psychoactive compound Δ9-tetrahydrocannabinol. When cannabis is heated in vacuum, the decarboxylation of tetrahydrocannabinolic acid (THCA) appears to follow first order kinetics. The log fraction of THCA present decreases steadily over time, and the rate of decrease varies according to temperature. At 10-degree increments from 100 to 140 °C, half of the THCA is consumed in 30, 11, 6, 3, and 2 minutes; hence the rate constant follows Arrhenius' law, ranging between 10−8 and 10−5 in a linear log–log relationship with inverse temperature. However, modelling of decarboxylation of salicylic acid with a water molecule had suggested an activation barrier of 150 kJ/mol for a single molecule in solvent, much too high for the observed rate. Therefore, it was concluded that this reaction, conducted in the solid phase in plant material with a high fraction of carboxylic acids, follows pseudo–first-order kinetics in which a nearby carboxylic acid precipitates without affecting the observed rate constant. Two transition states corresponding to indirect and direct keto-enol routes are possible, with energies of 93 and 104 kJ/mol. Both intermediates involve protonation of the alpha carbon, disrupting one of the double bonds of the aromatic ring and permitting the beta-keto group (which takes the form of an enol in THCA and THC) to participate in decarboxylation. In beverages stored for long periods, very small amounts of benzene may form from benzoic acid by decarboxylation catalyzed by the presence of ascorbic acid.
=== Affinity labeling === Affinity label is a molecule that is similar in structure to a particular substrate for a specific enzyme. It is considered to be a class of irreversible inhibitors. These molecules covalently modify active site residues in order to elucidate the structure of the active site. Using this method, Wilchek collaborated with a team who proved that the binding site of antibodies lies in the Fv portion of the molecule and involves three hypervariable sites, today called the complementarity-determining regions (CDRs).
==== Groundwater ==== In saturated groundwater aquifers, all available pore spaces are filled with water (volumetric water content = porosity). Above a capillary fringe, pore spaces have air in them too. Most soils have a water content less than porosity, which is the definition of unsaturated conditions, and they make up the subject of vadose zone hydrogeology. The capillary fringe of the water table is the dividing line between saturated and unsaturated conditions. Water content in the capillary fringe decreases with increasing distance above the phreatic surface. The flow of water through and unsaturated zone in soils often involves a process of fingering, resulting from Saffman–Taylor instability. This results mostly through drainage processes and produces and unstable interface between saturated and unsaturated regions. One of the main complications which arises in studying the vadose zone, is the fact that the unsaturated hydraulic conductivity is a function of the water content of the material. As a material dries out, the connected wet pathways through the media become smaller, the hydraulic conductivity decreasing with lower water content in a very non-linear fashion. A water retention curve is the relationship between volumetric water content and the water potential of the porous medium. It is characteristic for different types of porous medium. Due to hysteresis, different wetting and drying curves may be distinguished.
Sources: en.wikipedia.org
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。
生长激素释放激素通过其专用受体起作用，而 ipamorelin 主要作用于胃饥饿素受体。两者可影响生长激素释放，但信号通路和下游效应并不相同。
研究多集中在生长激素释放的急性调节、受体选择性以及不同给药方式下的药代动力学。临床终点研究数量有限，长期结局尚不明确。
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.