A practical reference on GHS-R1a: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-05. Anything still debated is marked as such rather than presented as settled.
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.
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 | 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 |
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.
One distinguishing feature reported in animal studies is selectivity. Ipamorelin stimulated growth hormone release with limited elevation of adrenocorticotropic hormone or cortisol compared with earlier secretagogues such as GHRP-6. This pattern has been described as more selective for the growth hormone axis. The finding comes mainly from preclinical work, and the degree to which it holds across species and doses is not fully settled. Reports also describe effects on gastric motility in animal models, suggesting activity outside the pituitary, though the clinical relevance of this observation is uncertain.
Ipamorelin is a synthetic pentapeptide that acts on the growth hormone secretagogue receptor, also known as the ghrelin receptor. Its sequence contains five amino acid residues, including a non-natural residue that increases stability against enzymatic breakdown. The compound was developed in the 1990s as part of research into small peptides that stimulate pituitary hormone release. Unlike larger protein hormones, it can be produced by solid-phase peptide synthesis and characterized by standard analytical methods.
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。
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.
On 5 October, the 2025 Syrian parliamentary election was held in the temporary electoral system as an indirect vote, where only around 6,000 selected Syrians were eligible. 140 members were due to be elected by the electoral college, although only 119 were elected on election day due to postponement in select areas from security concerns. On 1 July, President Ahmed al-Sharaa appointed the remaining 70 additional members. The People's Assembly building underwent renovation by late 2025, the first since 2009, delaying the appointment of the 70 seats appointed by the president of Syria. While in at a meeting in the Royal Institute of International Affairs on 31 March 2026, al-Sharaa announced that the People's Assembly will be seated within the month. The first post-Assad People's Assembly was subsequently finalized in early July 2026, with its inaugural session originally scheduled for 6 July; however, a day before the scheduled date, the Higher Committee for People's Assembly Elections had announced that the inaugural session will be postponed to a later date. The inaugural session of the People's Assembly was held on 12 July 2026. At its second session, the Assembly passed a resolution setting up much of its internal procedures and structure; among the articles were provisions that the parliament cannot be dissolved by the President, must ratify international agreements and constitutional amendments, will broadcast its sessions publicly, and retains parliamentary immunity for its members only for when conducting parliamentary affairs.
The motor by Kelly and co-workers is an elegant example of how chemical energy can be used to induce controlled, unidirectional rotational motion, a process which resembles the consumption of ATP in organisms in order to fuel numerous processes. However, it does suffer from a serious drawback: the sequence of events that leads to 120° rotation is not repeatable. Kelly and co-workers have therefore searched for ways to extend the system so that this sequence can be carried out repeatedly. Unfortunately, their attempts to accomplish this objective have not been successful and currently the project has been abandoned. In 2016 David Leigh's group invented the first autonomous chemically-fuelled synthetic molecular motor. Some other examples of synthetic chemically driven rotary molecular motors that all operate by sequential addition of reagents have been reported, including the use of the stereoselective ring opening of a racemic biaryl lactone by the use of chiral reagents, which results in a directed 90° rotation of one aryl with respect to the other aryl. Branchaud and co-workers have reported that this approach, followed by an additional ring closing step, can be used to accomplish a non-repeatable 180° rotation.
== In transplant rejection == In a transplant procedure, as of an organ or stem cells, MHC molecules themselves act as antigens and can provoke immune response in the recipient, thus causing transplant rejection. MHC molecules were identified and named after their role in transplant rejection between mice of different strains, though it took over 20 years to clarify MHC's role in presenting peptide antigens to cytotoxic T lymphocytes (CTLs). Each human cell expresses six MHC class I alleles (one HLA-A, -B, and -C allele from each parent) and six to eight MHC class II alleles (one HLA-DP and -DQ, and one or two HLA-DR from each parent, and combinations of these). The MHC variation in the human population is high, at least 350 alleles for HLA-A genes, 620 alleles for HLA-B, 400 alleles for DR, and 90 alleles for DQ. Any two individuals who are not identical twins, triplets, or higher order multiple births, will express differing MHC molecules. All MHC molecules can mediate transplant rejection, but HLA-C and HLA-DP, showing low polymorphism, seem least important. When maturing in the thymus, T lymphocytes are selected for their TCR incapacity to recognize self antigens, yet T lymphocytes can react against the donor MHC's peptide-binding groove, the variable region of MHC holding the presented antigen's epitope for recognition by TCR, the matching paratope. T lymphocytes of the recipient take the incompatible peptide-binding groove as nonself antigen. There are various types of transplant rejection that are known to be mediated by MHC (HLA):
Breast cancer, which develops from breast tissue, is the most common cause of cancer death among women and a leading cause of general death among women. Factors that appear to be implicated in decreasing the risk of breast cancer are regular breast examinations by health care professionals, regular mammograms, self-examination of breasts, healthy diet, exercise to decrease excess body fat, and breastfeeding.
In 2010, the BBC reported that use of MDMA had decreased in the UK in previous years. This may be due to increased seizures during use and decreased production of the precursor chemicals used to manufacture MDMA. Unwitting substitution with other drugs, such as mephedrone and methamphetamine, as well as legal alternatives to MDMA, such as BZP, MDPV, and methylone, are also thought to have contributed to its decrease in popularity. In 2017, it was found that some pills being sold as MDMA contained pentylone, which can cause very unpleasant agitation and paranoia. According to David Nutt, when safrole was restricted by the United Nations in order to reduce the supply of MDMA, producers in China began using anethole instead, but this gives para-methoxyamphetamine (PMA, also known as "Dr Death"), which is much more toxic than MDMA and can cause overheating, muscle spasms, seizures, unconsciousness, and death. People wanting MDMA are sometimes sold PMA instead. In 2025, the BBC reported on a study of 650 survivors from the Nova music festival massacre. Two-thirds were under the influence of recreational drugs (MDMA, LSD, marijuana or psilocybin) when Hamas attacked the festival on October 7, 2023. MDMA appeared to have a protective effect against later problems with sleeping and emotional distress.
Sources: en.wikipedia.org
On the one hand, God remains responsible as the creator of the world and is thus also the ultimate cause of suffering—at least in the sense that his creation of the world made suffering possible in the first place. On the other hand, there are situations in which no finite power can save or help human beings. For by definition, only God is the reality that can save us even in death—if he exists. But how can I ask for help from the very one who made my misery possible in the first place? Kermani sees no way to rationally justify this question. Rather, he describes those voices that do not want to abandon God even in misery. The fools he cites do not simply lament the terror of God. Instead, they remind God of the promises he once made in creation. They insist on God's faithfulness, which God describes and promises in His self-revelation. The fools are therefore not blind to reality. On the contrary, they consider all the questions about the reality of a loving God that every human being experiences on a daily basis. Their adherence to God does not dull their senses or take away the horror of suffering. But it enables them to face the abysses and terror of reality without, however, giving up hope. Belief in God thus operates as an imposition that can drive one to madness. At the same time, however, it appears as the last possibility for putting up with the world in its ambiguity without losing one's own humanity.
=== American Hospital Association (AHA) === The American Hospital Association has expressed concern that FDA's proposal to classify LDTs as medical devices exceeds the agency's appropriate regulatory scope, urging the FDA to continue to apply its enforcement discretion to hospital and health system LDTs and defer regulation of these tests mainly to CMS's strict CLIA oversight, the CAP accreditation and state law. The organization has called on Congress to either exclude hospitals and health systems from this device classification framework or to modernize LDT oversight in a way that promotes innovation while maintaining test accessibility, safety, and effectiveness.
The Weismann barrier, proposed by August Weismann in 1892, distinguishes between the "immortal" germ cell lineages (the germ plasm) which produce gametes and the "disposable" somatic cells. Hereditary information moves only from germline cells to somatic cells (that is, somatic mutations are not inherited). This, before the discovery of the role or structure of DNA, does not predict the central dogma, but does anticipate its gene-centric view of life, albeit in non-molecular terms.
In the March 2005 issue of Science, Mary Higby Schweitzer of North Carolina State University and colleagues announced the recovery of soft tissue from the marrow cavity of a fossilized leg bone from a T. rex. The bone had been intentionally, though reluctantly, broken for shipping and then not preserved in the normal manner, specifically because Schweitzer was hoping to test it for soft tissue. Designated as the Museum of the Rockies specimen 1125, or MOR 1125, the dinosaur was previously excavated from the Hell Creek Formation. Flexible, bifurcating blood vessels and fibrous but elastic bone matrix tissue were recognized. In addition, microstructures resembling blood cells were found inside the matrix and vessels. The structures bear resemblance to ostrich blood cells and vessels. Whether an unknown process, distinct from normal fossilization, preserved the material, or the material is original, the researchers do not know, and they are careful not to make any claims about preservation. If it is found to be original material, any surviving proteins may be used as a means of indirectly guessing some of the DNA content of the dinosaurs involved, because each protein is typically created by a specific gene. The absence of previous finds may be the result of people assuming preserved tissue was impossible, therefore not looking. Since the first, two more tyrannosaurs and a hadrosaur have also been found to have such tissue-like structures. Research on some of the tissues involved has suggested that birds are closer relatives to tyrannosaurs than other modern animals.
Sources: en.wikipedia.org
Analysis of the debris at the test site of the United States' first thermonuclear weapon, Ivy Mike (1 November 1952, Enewetak Atoll), besides einsteinium, fermium, plutonium and americium also revealed isotopes of berkelium, californium and curium, in particular 245Cm, 246Cm and smaller quantities of 247Cm, 248Cm and 249Cm. Atmospheric curium compounds are poorly soluble in common solvents and mostly adhere to soil particles. Soil analysis revealed about 4,000 times higher concentration of curium at the sandy soil particles than in water present in the soil pores. An even higher ratio of about 18,000 was measured in loam soils. The transuranic elements up to fermium, including curium, should have been present in the natural nuclear fission reactor at Oklo, but any quantities produced then would have long since decayed away.
=== Nymphs === It is often difficult to distinguish Eupolyphaga species by their nymphs. Nymphs are generally similar in appearance to females, being reddish brown to dark brown in color, though lighter variations are possible. They will appear white in color prior to sclerotization. While common throughout the genus, sex of individuals can be determined in the last nymphal instar, largely due to their sexual dimorphism at maturity. Male nymphs have four distinct wing buds, while the females have none.
Chiang's general He Yingqin then proposed building a highway from Kangding to Xining through Yushu, but Liu once again blocked Nationalist attempts to introduce its soldiers in Xikang. Kim Hee-shin argues that Liu, in his dealings with various political factions, was mainly driven by political survival, with ideology playing little to no role in his considerations. This meant that although Xikang cooperated with the central government, he maintained ties with anti-Chiang factions and refused to let Nationalist garrisons into his province. An attempt by the Nationalist official H. H. Kung to more closely oversee Xikang's affairs in 1939 ended in failure after the representative he sent, Peter Goullart, was placed under house arrest by Liu's forces. To prevent the CC Clique from taking control of his province, Liu used his position as head of the provincial government to block their influence.
== Research == The current 'best' practice in the UK is to treat the underlying venous reflux once an ulcer has healed. It is questionable whether endovenous treatment should be offered before ulcer healing, as current evidence would not support this approach as standard care. The EVRA (Early Venous Reflux Ablation) ulcer trial, a randomised clinical trial funded by the National Institute for Health and Care Research (NIHR) to compare early versus delayed endovenous treatment of superficial venous reflux in patients with chronic venous ulceration, opened for recruitment in October 2013. The study hopes to show an increase in healing rates from 60% to 75% at 24 weeks. Research from the University of Surrey and funded by the Leg Ulcer Charity looked at the psychological impact of having a leg ulcer, on the relatives and friends of the affected person, and the influence of treatment.
In December 2017, Tim Hortons opened two stores in the centre of Madrid and later opened another in the city of Pozuelo de Alarcón in the Community of Madrid. The menu also includes typical Spanish drinks apart from the typical drinks of a Tim Hortons.
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.
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。