If you have been reading about incretin and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
The GIP receptor is expressed in pancreatic islets, adipose tissue, and the central nervous system, while GLP-1 receptors are found in pancreatic islets, the gastrointestinal tract, and the brain. Activation of both receptors can enhance glucose-dependent insulin secretion and reduce glucagon release. The relative contribution of each receptor to the overall pharmacological effect remains an area of ongoing investigation. Preclinical studies suggest that GIP receptor agonism may modulate appetite and energy balance, but the precise mechanisms in humans are not fully established.
In clinical research, tirzepatide has been studied in randomized controlled trials for glycemic control and body weight reduction. These trials typically measure changes in hemoglobin A1c and body weight over periods of several months. The drug is administered by subcutaneous injection, and its pharmacokinetic profile supports once-weekly dosing. Post-marketing surveillance continues to evaluate long-term outcomes and rare adverse events.
Tirzepatide is a synthetic peptide that acts as a dual agonist at the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. The molecule contains 39 amino acids and features a C20 fatty diacid moiety attached via a linker, which promotes albumin binding and extends its circulating half-life. Its sequence incorporates non-natural amino acids and modifications that reduce susceptibility to degradation by dipeptidyl peptidase-4. This dual receptor activity distinguishes it from selective GLP-1 receptor agonists.
脂肪酸侧链的存在使该肽与血浆白蛋白结合能力增强，从而延长循环半衰期，支持每周一次给药的用药间隔。白蛋白结合同时改变组织分布特征，减慢肾脏清除速度。该设计思路在多种长效肽类药物中被反复采用，属于既定的药代动力学策略。
该化合物的名称与结构由国际非专利名称体系统一维持，不同文献中出现的同义写法主要在拼写顺序或盐形式描述上不同。研究者通常通过受体结合实验、细胞内环磷酸腺苷积累测定以及动物模型来确认其双激动活性。相当一部分分子层面的细节——例如两条受体通路之间的信号交叉作用——尚处于开放问题状态。
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | Dual GIP/GLP-1 receptor agonist |
| Amino acid count | 39 | Contains non-natural residues |
| Modification | C20 fatty diacid | Attached via linker; promotes albumin binding |
| Half-life | Approximately 5 days | Supports once-weekly dosing |
| Primary route | Subcutaneous injection | Not for intravenous use |
Tirzepatide is a synthetic peptide of 39 amino acids engineered from the native glucose-dependent insulinotropic polypeptide sequence. Its structure incorporates several non-natural residues and a C-terminal segment derived from glucagon-like peptide-1, together with a C20 fatty diacid moiety attached through a linker. The lipophilic side chain promotes binding to serum albumin, which slows renal clearance after administration. The compound is classified as a dual incretin receptor agonist and is supplied as a lyophilized powder for reconstitution or as a preformulated solution, depending on the presentation.
The peptide activates two G protein-coupled receptors, GIPR and GLP-1R. Binding triggers adenylyl cyclase activity and raises intracellular cyclic AMP in pancreatic beta cells, which potentiates insulin release when glucose is elevated. Signaling in the central nervous system is associated with reduced appetite and lower energy intake, while effects on gastric emptying and glucagon secretion are also reported. Because activity at both receptors is retained, the pharmacological profile is often described as incretin-based rather than selective for a single receptor.
After subcutaneous injection, absorption is gradual, and peak plasma levels are generally reached within one to three days. Albumin binding extends the apparent half-life to roughly five days, which supports a weekly administration schedule. Metabolism proceeds mainly through proteolytic cleavage of the peptide backbone and beta-oxidation of the fatty acid chain, rather than through cytochrome P450 pathways. Eliminated fragments are largely recycled through general protein turnover, and excretion of intact drug in urine is minimal. These properties distinguish the molecule from short-acting incretin mimetics.
Like most synthetic peptides of this size, the material is commonly supplied as a lyophilised powder that appears white to off-white. It dissolves in aqueous buffers and in mixtures of water with a small proportion of organic solvent, though the fatty acid portion reduces solubility in pure water relative to short peptides. Hygroscopic behaviour is reported for many peptide powders, so weighing is usually performed quickly and under controlled humidity. Working solutions are typically prepared fresh and kept cold.
Long-term storage of lyophilised peptide powder is generally at minus twenty degrees Celsius or colder, with desiccant and protection from light. Short-term storage at two to eight degrees Celsius is common during active use. In solution, stability depends strongly on pH, concentration, and the presence of preservatives, and hydrolysis or aggregation can develop over weeks. Published stability data specific to this molecule are limited, so recommended conditions for research material are usually extrapolated from general peptide handling practice rather than from a dedicated study.
Regulatory and quality discussions place the peptide within established guidance for synthetic peptides and biologics. Forced degradation studies, in which samples are exposed to heat, acid, base, peroxide, and light, identify likely degradation products and validate the selectivity of analytical methods. Reference standards allow comparison across laboratories and production batches. Purity specifications reported in the literature usually combine chromatographic purity with mass confirmation. Which impurity thresholds are meaningful for long-term behavior is still debated, and no single universal specification has been adopted across all jurisdictions.
Routine characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity assessment, usually with ultraviolet detection near 214 nanometers. Intact mass measurement by liquid chromatography coupled to mass spectrometry confirms molecular identity against a theoretical value. Sequence-level confirmation uses enzymatic digestion followed by tandem mass spectrometry, an approach known as peptide mapping. Amino acid analysis gives an independent check on composition. Circular dichroism spectra are used to estimate helical content in aqueous buffer.
Stability depends strongly on physical form. The dry powder is generally regarded as stable for extended periods when held at or below minus twenty degrees Celsius in a sealed, desiccated container. In solution, degradation pathways include deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation. Reaction rates for these pathways rise with temperature. Repeated freezing and thawing of solutions promotes aggregation, and light exposure can accelerate some oxidative changes. Buffer composition and pH influence which pathway dominates at a given temperature.
Dual agonism at the GIP and GLP-1 receptors underlies the observed pharmacology. Activation of GLP-1 receptors raises glucose-dependent insulin release, lowers glucagon secretion, slows gastric emptying and reduces appetite. GIP receptor activation contributes additional effects on adipose tissue and on energy balance, and the combined action on appetite appears larger than either pathway alone in animal models. Signalling bias and the relative contribution of each receptor arm to weight-related effects remain areas of active investigation.
Structure-activity work shows that fatty acid length, linker chemistry and the position of acylation all influence albumin affinity and receptor potency. Plasma protein binding exceeds 99 percent, which restricts distribution and slows renal clearance. Degradation proceeds largely through general proteolysis and fatty acid oxidation rather than cytochrome P450 metabolism, so exposure to common oxidative drug interactions is limited. Whether these clearance routes vary meaningfully between individuals is not fully established.
The availability of furikake in Japan increased starting shortly after September 1948, when Nissin Foods began to manufacture it on a large scale to address pervasive malnourishment. The product was commercialized on the basis that it provided a good source of protein and calcium. Furikake was made widely available as it was dispensed to those serving in the Japanese military starting in World War I. The term furikake was used generically to describe the product starting in 1959 with the formation of the National Furikake Association. Since 1959, furikake products are usually differentiated by their particular ingredients, such as salmon furikake and sesame-and-salt furikake. In the same year, Marumiya Foods developed "Noritama," a sweetened egg added to Kore Wa Umai which became popular as furikake for children. In 1963, Noritama with a sticker of 8 Man became explosively popular, and furikake was transformed from a luxury food for adults to a popular food for children. In 1970, Mishima Shokuhin marketed a new furikake, made by reusing the red shiso used to color pickled plums, under the product name Yukari. The name comes from the desire to create a connection ("縁" (yukari) in Japanese) with customers. In the 1980s, furikake became strongly associated with children's food, and its use rapidly declined after the age of 12. In 1989, Nagatanien began selling "furikake for adults" using ingredients with a luxurious taste and pungent flavor. The initial varieties were "Salmon," "Bonito," and "Wasabi."
Controversy soon arose over the size of UNTAG's military component, as the member states of the Security Council expected to cover the majority of the costs were irritated by its relatively large size. However, Angola, Zambia, and other states sympathetic to PLAN insisted that a larger force was necessary to ensure that South Africa did not interfere with independence proceedings. Against their objections UNTAG's force levels were reduced from the proposed 7,500 to three battalions of 4,650 troops. This slashed projected expenses by nearly 300 million dollars, but the Security Council did not approve the revised budget until 1 March 1989. The inevitable delay in UNTAG's full deployment ensured there were insufficient personnel prepared to monitor the movement of PLAN and the SADF or their confinement to bases on 1 April 1989, when the permanent cessation in hostilities was to take effect. Secretary-General de Cuéllar urged restraint in the interim on both sides to avoid jeopardising the de facto ceasefire maintained since August 1988 or the 1 April implementation schedule. Nevertheless, PLAN took advantage of the political uncertainty in the weeks following the UNTAG budget debate to begin moving its forces in Angola closer to the border. Since the early 1980s PLAN had consistently stated its intention to establish camps inside South West Africa during any future political transition, a notion rejected with equal consistency by the South African government.
== Nomenclature == Various fairly standardized abbreviations for vaccine names have developed, although the standardization is by no means centralized or global. For example, the vaccine names used in the United States have well-established abbreviations that are also widely known and used elsewhere. An extensive list of them provided in a sortable table and freely accessible is available at a US Centers for Disease Control and Prevention web page. The page explains that "The abbreviations [in] this table (Column 3) were standardized jointly by staff of the Centers for Disease Control and Prevention, ACIP Work Groups, the editor of the Morbidity and Mortality Weekly Report (MMWR), the editor of Epidemiology and Prevention of Vaccine-Preventable Diseases (the Pink Book), ACIP members, and liaison organizations to the ACIP." Some examples are "DTaP" for diphtheria and tetanus toxoids and acellular pertussis vaccine, "DT" for diphtheria and tetanus toxoids, and "Td" for tetanus and diphtheria toxoids. At its page on tetanus vaccination, the CDC further explains that "Upper-case letters in these abbreviations denote full-strength doses of diphtheria (D) and tetanus (T) toxoids and pertussis (P) vaccine. Lower-case "d" and "p" denote reduced doses of diphtheria and pertussis used in the adolescent/adult-formulations.
Sources: en.wikipedia.org
A common assertion in the US and the UK is that heavy consumption of turkey meat—as seen during Thanksgiving and Christmas—results in drowsiness, due to high levels of tryptophan contained in turkey. However, the amount of tryptophan in turkey is comparable with that of other meats. Drowsiness after eating may be caused by other foods eaten with the turkey, particularly carbohydrates. Ingestion of a meal rich in carbohydrates triggers the release of insulin. Insulin in turn stimulates the uptake of large neutral branched-chain amino acids (BCAA), but not tryptophan, into muscle, increasing the ratio of tryptophan to BCAA in the blood stream. The resulting increased tryptophan ratio reduces competition at the large neutral amino acid transporter (which transports both BCAA and aromatic amino acids), resulting in more uptake of tryptophan across the blood–brain barrier into the cerebrospinal fluid (CSF). Once in the CSF, tryptophan is converted into serotonin in the raphe nuclei by the normal enzymatic pathway. The resultant serotonin is further metabolised into the hormone melatonin—which is an important mediator of the circadian rhythm—by the pineal gland. Hence, these data suggest that "feast-induced drowsiness"—or postprandial somnolence—may be the result of a heavy meal rich in carbohydrates, which indirectly increases the production of melatonin in the brain, and thereby promotes sleep.
Psychedelic microdosing is the practice of using sub-threshold doses (microdoses) of psychedelics in an attempt to improve creativity, boost physical energy level, emotional balance, increase performance on problems-solving tasks and to treat anxiety, depression and addiction. The practice of microdosing has become more widespread in the 21st century with more people claiming long-term benefits from the practice. A 2022 study recognized signatures of psilocybin microdosing in natural language and concluded that low amount of psychedelics have potential for application, and ecological observation of microdosing schedules.
One of the oldest ways to pump air. A simple mechanism that consists of a flexible bag that has rigid boards or handles on each side. The bag can be expanded and contracted by working the handles away from each other and together forcing air out of the nozzle. When the bag is inflated or the handles are pulled away from each other a valve is opened on the side allowing air in. When the handles are pushed together that valve is closed and air is forced out the end. Bicycle Pump
Sources: en.wikipedia.org
== Mechanism == AGRP has been demonstrated to be a competitive antagonist of melanocortin receptors, specifically MC3-R and MC4-R. The melanocortin receptors, MC3-R and MC4-R, are directly linked to metabolism and body weight control. These receptors are activated by the peptide hormone α-MSH (melanocyte-stimulating hormone) and antagonized by the agouti-related protein. Whereas α-MSH acts broadly on most members of the MCR family (with the exception of MC2-R), AGRP is highly specific for only MC3-R and MC4-R. This inverse agonism not only antagonizes the action of melanocortin agonists such as α-MSH but also further decreases the cAMP produced by the affected cells. The exact mechanism by which AgRP inhibits melanocortin-receptor signalling is not completely clear. It has been suggested that Agouti-related protein binds MSH receptors and acts as a competitive antagonist of ligand binding. Studies of Agouti protein in B16 melanoma cells supported this logic. The expression of AgRP in the adrenal gland is regulated by glucocorticoids. The protein blocks α-MSH-induced secretion of corticosterone.
=== In the Antarctic === The first cold seep from the Southern Ocean was reported in 2005. The relatively few investigations to the Antarctic deep sea have shown the presence of deep-water habitats, including hydrothermal vents, cold seeps, and mud volcanoes. Other than the Antarctic Benthic Deep-Sea Biodiversity Project (ANDEEP) cruises, little work has been done in the deep sea. There are more species waiting to be described.
Before the ghetto riot of 1967, Detroit's black population had the highest rate of home-ownership of any black urban population in the country, and their unemployment rate was just 3.4 percent. It was not despairing that fueled the riot. It was the riot which marked the beginning of the decline of Detroit to its current state of despair. Detroit's population today is only half of what it once was, and its most productive people have been the ones who fled. However, Thomas Sugrue argues that over 20% of Detroit's adult black population was out of work in the 1950s and 1960s, along with 30% of black youth between eighteen and twenty-four. Economist Edward L. Glaeser believes the riots were a symptom of the city's already downward trajectory:
== ICH GCP overview == Glossary Principles of ICH GCP Guidelines for: institutional review board (IRB) / independent ethics committee (IEC) investigator trial sponsor (industrial, academic) clinical trial protocol and protocol amendments investigator's brochure essential documents
Sources: en.wikipedia.org
It activates both GIP and GLP-1 receptors. This dual action differentiates it from selective GLP-1 agonists.
It is given as a subcutaneous injection. Its long half-life supports weekly dosing.
No, it is synthetic. It contains non-natural amino acids and a fatty acid modification.
它属于合成修饰肽，同时激动 GIP 与 GLP-1 两种肠促胰素受体。这类分子通常被称为双重肠促胰素受体激动剂，与选择性 GLP-1 激动剂在靶点范围上不同。