GHSR-1a is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-01-12. Numbers and descriptions here follow the published literature rather than marketing material.
Ipamorelin 是一种合成五肽，序列为 Aib-His-D-2-Nal-D-Phe-Lys-NH2，分子式 C38H49N9O5，游离碱分子量约 711.85 g/mol。它属于生长激素促分泌素（GHS）家族，作用靶点是胃饥饿素受体 GHS-R1a。该化合物由诺和诺德的研究团队在二十世纪九十年代末报道，设计目标是提高对生长激素释放的选择性。C 端酰胺化与 N 端 Aib 残基是两个用于抵抗肽酶降解的结构特征。
在 GHS 家族中，早期肽类如 GHRP-6 与 GHRP-2 会同时促进生长激素、皮质醇与催乳素的释放，并明显增加食欲。Ipamorelin 在动物与早期人体研究中表现出对生长激素释放的相对选择性，对上述其他激素的影响较小。这种差异通常归因于受体结合模式与下游信号偏向的不同，而完整的分子解释仍有待补充。需要区分的是，选择性是研究观察中的相对程度，并非绝对界限。
从用途定位看，ipamorelin 目前主要以研究用肽的身份被讨论，未见主要药品监管机构将其批准为治疗药物。市售材料通常标注仅供研究使用，不得用于人体或诊断程序。文献中它常与生长激素促分泌素、GHS-R1a 激动剂、胃饥饿素拟似物等表述并列出现。既有研究的样本量普遍偏小，因此对其效应强度与一致性的描述应保持谨慎。
杂质谱一般包含缺失序列片段、差向异构体、氧化产物以及残留溶剂或反离子，其中组氨酸与芳香残基的氧化常被重点关注。反相色谱中这类杂质往往紧邻主峰洗脱，因此方法需要足够的分离度并经过系统适用性验证。纯度百分比的解读依赖于检测波长与梯度条件，不同实验室公布的数字不宜直接横向比较。参考标准品有助于跨批次对照，但其自身赋值同样需要可追溯来源。
冻干状态下的肽通常比溶液状态更稳定，常规做法是维持 -20 °C 或更低温度、保持干燥并避开强光。复溶后的降解主要来自水解、氧化与脱酰胺，速率受 pH、缓冲液种类、离子强度与温度共同影响，碱性条件一般会加快这些反应。反复冻融会造成聚集与容器吸附损失，分装保存能降低该风险。容器材质与金属离子也可能参与氧化过程，需与操作条件一并考虑。
| Property | Value | Notes |
|---|---|---|
| 分子式 | C38H49N9O5 | 五肽，C 端酰胺化 |
| 分子量 | 约 711.85 g/mol | 游离碱形式 |
| 外观 | 白色至类白色冻干粉 | 研究用材料的常见形态 |
| 溶解性 | 溶于水及 DMSO 等极性溶剂 | 建议现配现用 |
| 储存温度 | -20 °C 或更低 | 干燥、避光、限制冻融次数 |
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.
Selectivity distinguishes ipamorelin from first-generation secretagogues such as GHRP-6. At doses that reliably raise growth hormone, it shows little stimulation of adrenocorticotropic hormone or cortisol release in animal models, and it does not markedly raise prolactin or appetite. Binding at GHS-R1a on pituitary somatotrophs triggers calcium influx and pulsatile growth hormone secretion. Because the compound mimics the natural ghrelin signal, the release pattern tends to follow the body's own rhythm rather than producing a sustained elevation.
Quality claims for research peptides vary widely across suppliers. A certificate of analysis should list purity by chromatography, the mass found by spectrometry, and the analytical conditions used. Independent testing at a third-party laboratory is a common way to check identity and purity, because documents alone cannot confirm what is inside a vial. Purity figures describe the proportion of the target peptide among detected species, and they say nothing about biological activity or sterility.
Lyophilized ipamorelin powder is the form usually supplied for laboratory work. Kept dry, protected from light, and held at minus 20 degrees Celsius or below, it remains stable for extended periods, often measured in years. Once dissolved, the peptide degrades faster through hydrolysis, oxidation, and deamidation, so solutions are typically refrigerated and used within weeks. Repeated freeze-thaw cycles and exposure to alkaline conditions accelerate loss of the parent compound.
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.
Published animal and early human work describes growth hormone release that is separated from comparable rises in adrenocorticotropic hormone and cortisol. Prolactin changes are reported as small in the same studies. Selectivity is attributed to binding at the ghrelin receptor and to the downstream signaling that follows, rather than to differences in how quickly the peptide is cleared. Authors commonly label the compound selective rather than potent, because the same mass produces a smaller growth hormone response than some older secretagogues tested in parallel. Whether that profile holds across species and routes of administration remains an open question.
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.
Visceral fat or abdominal fat (also known as organ fat or intra-abdominal fat) is located inside the abdominal cavity, packed between the organs (stomach, liver, intestines, kidneys, etc.). Visceral fat is different from subcutaneous fat underneath the skin, and intramuscular fat interspersed in skeletal muscles. Fat in the lower body, as in thighs and buttocks, is subcutaneous and is not consistently spaced tissue, whereas fat in the abdomen is mostly visceral and semi-fluid. Visceral fat is composed of several adipose depots, including mesenteric, epididymal white adipose tissue (EWAT), and perirenal depots. Visceral fat is often expressed in terms of its area in cm2 (VFA, visceral fat area). An excess of visceral fat is known as abdominal obesity, or "belly fat", in which the abdomen protrudes excessively. New developments such as the Body Volume Index (BVI) are specifically designed to measure abdominal volume and abdominal fat. Excess visceral fat is also linked to type 2 diabetes, insulin resistance, inflammatory diseases, and other obesity-related diseases. Likewise, the accumulation of neck fat (or cervical adipose tissue) has been shown to be associated with mortality. Several studies have suggested that visceral fat can be predicted from simple anthropometric measures, and predicts mortality more accurately than body mass index or waist circumference. Men are more likely to have fat stored in the abdomen due to sex hormone differences. Estrogen (female sex hormone) causes fat to be stored in the buttocks, thighs, and hips in women.
=== Photonics Lab on a Chip === Due to the increase in safety concerns and operating costs of common analytic methods (ICP-MS, ICP-AAS, and ICP-OES), the Photonics Lab on a Chip (PhLOC) is becoming an increasingly popular tool for the analysis of actinides and nitrates in spent nuclear waste. The PhLOC is based on the simultaneous application of Raman and UV-Vis-NIR spectroscopy, which allows for the analysis of more complex mixtures which contain several actinides at different oxidation states. Measurements made with these methods have been validated at the bulk level for industrial tests, and are observed to have a much lower variance at the micro-scale. This approach has been found to have molar extinction coefficients (UV-Vis) in line with known literature values over a comparatively large concentration span for 150 μL via elongation of the measurement channel, and obeys Beer's Law at the micro-scale for U(IV). Through the development of a spectrophotometric approach to analyzing spent fuel, an on-line method for measurement of reactant quantities is created, increasing the rate at which samples can be analyzed and thus decreasing the size of deviations detectable within reprocessing. Through the application of the PhLOC, flexibility and safety of operational methods are increased.
=== Reforms === In November 2013, at the conclusion of the third plenum of the 18th Central Committee, the Communist Party adopted the Decision on Several Major Issues Concerning Comprehensively Deepening Reform, a far-reaching reform agenda that alluded to changes in both economic and social policy. Xi signaled at the plenum that he was consolidating control of the massive internal security organization that was formerly the domain of Zhou Yongkang. The Central Leading Group for Comprehensively Deepening Reforms—another ad hoc policy coordination body led by Xi upgraded to a commission in 2018—was also formed to oversee the implementation of the reform agenda. Termed "comprehensive deepening reforms", they were said to be the most significant since Deng Xiaoping's 1992 Southern Tour. The plenum also announced economic reforms and resolved to abolish the laogai system of "re-education through labour", which was largely seen as a blot on China's human rights record. The system has faced significant criticism for years from domestic critics and foreign observers. In 2015, Xi announced the Four Comprehensives, namely comprehensively build a moderately prosperous society, deepening reform, governing the nation according to law, and strictly governing the Party; in 2021, at the 100th anniversary of the CCP, Xi declared that China achieved its goal of building a moderately prosperous society in all respects. In January 2016, a two-child policy replaced the one-child policy, which was in turn was replaced with a three-child policy in May 2021.
=== Droplet merging === As an existing droplet can be split to form discrete droplets using electrodes (see From an existing droplet), droplets can be merged into one droplet by electrodes as well. Utilizing the same concept applied for creating new droplets through splitting an existing droplet with electrodes, an aqueous droplet resting on an uncharged electrode can move towards a charged electrode where droplets will join and merge into one droplet. However, the merged droplet might not always form a circular shape even after the merging process is over due to surface tension. This problem can be solved by implementing a superhydrophobic surface between the droplets and the electrodes. Oil droplets can be merged in the same way as well, but oil droplets will move towards uncharged electrodes unlike aqueous droplets.
Sources: en.wikipedia.org
=== February === 2 February – Auckland Transport raises fares on buses, trains and ferries by 5.2% and ends the 10% off-peak discount. 3 February – The Tāhuna Glenorchy area of Central Otago is certified a Dark Sky Sanctuary, the 23rd such designation in the world and fifth in New Zealand. 4 February – 900 private sector laboratory workers strike to protest poor conditions and a lack of pay parity with their public sector counterparts. 5 February: The New Zealand Government confirms it will invest between NZ$100–150 million in upgrading State Highway 76 in Christchurch. It is announced that New Zealand's unemployment rate reaches 5.1%, the highest level since September 2020. Several Māori leaders and attendees protest against several government ministers including David Seymour, Paul Goldsmith and Shane Jones during a pōwhiri leading up to Waitangi Day. Seymour's speech is disrupted while Jones threatens to cut government funding to the Waitangi National Trust. 6 February: Prime Minister Christopher Luxon attends Waitangi Day celebrations at Ngāi Tahu's Ōnuku marae in Akaroa. The town hall in Roxburgh, Otago, which included the country's longest-running cinema, is destroyed by fire. The former building for New Zealand's sole Jewish school "Kadimah School" is vandalised with antisemitic graffiti referencing the Gaza war. 7 February: Health New Zealand chief executive Margie Apa resigns four months before the end of her contract. Taupō experiences heavy showers and thunderstorms, resulting in surface flooding and power outages.
In 2009, Geng’s group first achieved online two-dimensional (2D) separation of intact proteins using a single column possessing separation features of weak-cation exchange chromatography (WCX) and HIC (termed as two-dimensional liquid chromatography using a single column, (2D-LC-1C).
==== Austria ==== The highest radon concentrations in Austria were measured in 1991 in the municipality of Umhausen in Tyrol. Umhausen has about 2300 inhabitants and is located in the Ötztal valley. Some of the houses there were built on a bedrock of granite gneiss. From this porous subsoil, the radon present in the rock seeped freely into the unsealed cellars, which were contaminated with up to 60,000 Becquerels of radon per cubic meter of air. Radon levels in the apartments in Umhausen have been systematically monitored since 1992. Since then, extensive radon mitigation measures have been implemented in the buildings: New buildings, sealing of cellar floors, forced ventilation of cellars or relocation. Queries in the Austrian Health Information System (ÖGIS) have shown that the incidence of new cases of lung cancer has declined sharply since then. The Austrian National Radon Project (ÖNRAP) has studied radon exposure throughout the country. Austria also has a Radiation Protection Act as a legal basis. Indoor limits were set in 2008 The Austrian Ministry of the Environment states that
== Taxonomy == Although unnamed Ambrosiella-like fungi had previously been documented from the galleries and mycangia of native X. crassiusculus populations in central Japan, A. roeperi was first described as a novel species of ambrosia fungus by Harrington and McNew in 2014 based on isolations from beetles collected and trapped in the eastern United States, where it is invasive. It has not been assigned a common name at the time of this writing. All Ambrosiella are ambrosia beetle symbionts and belong to the family Ceratocystidaceae, which, where sexual stages are recognized, produce round, ostiolate (with a pore) fruiting bodies for their ascospores with a fine peridium (outer layer) and aseptate (lacking crosswalls) paraphyses (sterile tissue found among – and arising from the same surface as – spore-bearing cells). This family also includes Ceratocystis, representing several plant pathogens and sap-staining fungi, often transported by insects (including scolytine beetles); Chalaropsis, encompassing a few economically insignificant root diseases; Huntiella, primarily made up of saprobes associated with lesions on trees, transported by sap beetles and in one case an Ips bark beetle; Thielaviopsis, containing various agents of disease affecting monocots; Davidsoniella, comprising several species of tree pathogens, and Endoconidiophora, growing on conifers, producing disease and/or sap stain, and also often acting as a bark beetle associate.
==== Ireland ==== In Ireland, new regulations came into effect on 1 August 2010 concerning codeine, due to worries about the overuse of the drug. Codeine remains a semi non-prescriptive, over-the-counter drug up to a limit of 12.8 mg per pill, but codeine products must be out of the view of the public to facilitate the legislative requirement that these products "are not accessible to the public for self-selection". In practice, this means customers must ask pharmacists for the product containing codeine in name, and the pharmacist makes a judgement whether it is suitable for the patient to be using codeine, and that patients are fully advised of the correct use of these products. Products containing more than 12.8 mg codeine are available on prescription only.
Sources: en.wikipedia.org
To increase the potency they attached a phenolic group to the aromatic ring, N-methyl-trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine. That structure was used to design and develop other opioid receptors antagonists such as alvimopan. Alvimopan was approved later in 2008 for in-hospital use to increase the gastrointestinal function following a partial large or small bowel resection with primary anastomosis. Naloxegol was approved in September 2014 and naldemedine in March 2017, both for the treatment of OIC in adult patients with chronic cancer.
Bariatric surgery is an effective method for obese and diabetic individuals with MASLD to induce weight loss and reduce or resolve MASH inflammation, including fibrosis, and improve longevity. For the AASLD, bariatric surgery can be considered only for MASH on a case-by-case basis by an experienced bariatric surgery program. Indeed, some individuals might develop new or worsened features of MASLD. About 92% of people with MASLD experienced an improvement in steatosis, and 70% a complete resolution after bariatric surgery. A preoperative diet such as a low-calorie diet or a very-low-calorie diet is usually recommended to reduce liver volume by 16–20%. Preoperative weight loss is the only factor associated with postoperative weight loss. Preoperative weight loss can reduce operative time and hospital stay, although there is insufficient evidence whether preoperative weight loss reduces long-term morbidity or complications. Weight loss and decreases in liver size may be independent of the amount of calorie restriction. The APWG on MASLD recommends bariatric surgery as a treatment option for those with class II obesity (BMI >32.5 kg/m2 for Asians, 35 kg/m2 for Caucasians). They consider its effects on improving liver-related complications as unproven yet, but it effectively increases longevity by improving cardiovascular factors. Surgery carries more risks for individuals with MASH cirrhosis, with a review estimating overall morbidity to be 21%.
The enzyme characterised from Thiobacillus thioparus converts thiosulfate to sulfite and hydrogen sulfide by reaction with two units of glutathione, which is dimerised to glutathione disulfide. The enzyme has also been found in carp liver and yeast. This enzyme is a transferases, specifically a sulfurtransferases, which transfer sulfur-containing groups. The systematic name of this enzyme class is thiosulfate:thiol sulfurtransferase. Other names in common use include glutathione-dependent thiosulfate reductase, sulfane reductase, and sulfane sulfurtransferase.
=== Reproductive === Androgens such as testosterone, androstenedione and dihydrotestosterone are required for the development of organs in the male reproductive system, including the seminal vesicles, epididymis, vas deferens, penis and prostate. AAS are testosterone derivatives designed to maximize the anabolic effects of testosterone. AAS are consumed by elite athletes competing in sports like weightlifting, bodybuilding, and track and field. Male recreational athletes take AAS to achieve an "enhanced" physical appearance. AAS consumption disrupts the hypothalamic–pituitary–gonadal axis (HPG axis) in males. In the HPG axis, gonadotropin-releasing hormone (GnRH) is secreted from the arcuate nucleus of the hypothalamus and stimulates the anterior pituitary to secrete the two gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH). In adult males, LH stimulates the Leydig cells in the testes to produce testosterone which is required to form new sperm through spermatogenesis. AAS consumption leads to dose-dependent suppression of gonadotropin release through suppression of GnRH from the hypothalamus (long-loop mechanism) or from direct negative feedback on the anterior pituitary to inhibit gonadotropin release (short-loop mechanism), leading to AAS-induced hypogonadism.
==== Predicting molecular fingerprints ==== CSI:FingerID predicts a probabilistic fingerprint with a variety of molecular properties from several fingerprint types. The fingerprint is predicted from the given spectrum and its corresponding fragmentation tree using deep kernel learning, which is a combination of kernel methods and deep neural networks. Not only the top scoring molecular formula but multiple high-scoring molecular formula candidates are considered.
Sources: en.wikipedia.org
两者都是 GHS-R1a 激动剂，但 ipamorelin 在研究中显示出更高的生长激素释放选择性。早期资料显示它对皮质醇、催乳素与食欲的刺激弱于 GHRP-6。这些差异是相对程度，而非绝对区分。
公开资料中它主要以研究用肽的形式出现，未获主要监管机构批准用于治疗。可得材料通常标注仅供研究使用。任何临床用途的宣称都缺少监管依据。
序列中的 Aib 与 D-2-Nal 等非天然残基可提高对肽酶的抵抗能力，并影响受体结合的构象。这类修饰在合成肽设计中较为常见。它们也使常规氨基酸分析需要额外步骤才能确认序列。
Aib 即 α-氨基异丁酸，是一种非蛋白质源氨基酸，其侧链为两个甲基。它在肽链中倾向于诱导螺旋构象并限制骨架的柔性。这种刚性被认为有助于抵抗蛋白酶切割。