GLP-1 analog raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-08. Anything still debated is marked as such rather than presented as settled.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
该分子作为 GLP-1 受体的选择性激动剂发挥作用，受体属于 B 类 G 蛋白偶联受体家族，激活后经 Gs 通路提升细胞内环腺苷酸水平。在胰腺 β 细胞，信号促进葡萄糖依赖性的胰岛素释放，血糖偏低时该作用明显减弱。在胰岛 α 细胞，胰高血糖素分泌受到抑制。中枢神经系统与胃肠道同样存在受体表达，相应信号参与食欲调节以及胃排空速率的降低。
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
Two principal therapeutic variants exist under separate regulatory filings, one indicated for glycemic control in type 2 diabetes and one for chronic weight management. Both use the same active molecule; differences lie in formulation strength, titration schedule, and labeling. Regulatory agencies in the United States and European Union approved injectable forms in 2017 and 2018 respectively. An oral tablet formulation received approval later, using a carrier molecule to enhance absorption across the gastric epithelium. Labeling differs by jurisdiction and by indication.
The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.
Finite strain theory, also called large strain theory, large deformation theory, deals with deformations in which both rotations and strains are arbitrarily large. In this case, the undeformed and deformed configurations of the continuum are significantly different and a clear distinction has to be made between them. This is commonly the case with elastomers, plastically-deforming materials and other fluids and biological soft tissue. Infinitesimal strain theory, also called small strain theory, small deformation theory, small displacement theory, or small displacement-gradient theory where strains and rotations are both small. In this case, the undeformed and deformed configurations of the body can be assumed identical. The infinitesimal strain theory is used in the analysis of deformations of materials exhibiting elastic behavior, such as materials found in mechanical and civil engineering applications, e.g. concrete and steel. Large-displacement or large-rotation theory, which assumes small strains but large rotations and displacements.
(registration required) Shahid, I. (2000). "Tanūkh". In Bearman, P. J.; Bianquis, Th.; Bosworth, C. E.; van Donzel, E. & Heinrichs, W. P. (eds.). The Encyclopaedia of Islam, Second Edition. Volume X: T–U. Leiden: E. J. Brill. pp. 190–192. ISBN 978-90-04-11211-7. Sourdel, D. (1971). "Ḥawrān". In Lewis, B.; Ménage, V.L.; Pellat, Ch.; Schacht, J. (eds.). The Encyclopaedia of Islam, New Edition. Vol. III: H–Iram. Leiden: E.J. Brill. pp. 292–293. ISBN 90-04-08118-6. Stone, Christopher (2008). Popular Culture and Nationalism in Lebanon: The Fairouz and Rahbani Nation. Abingdon, Oxon and New York: Routledge. ISBN 978-0-415-77273-0.
== Art == Although some historians dates the start of the trepang industry to 1720, Regina Ganter of Griffith University suggests that the start of the industry may be around 1640. Artistic evidence, like the Arnhem land rock, also suggests that contact may go as far back as the 1500s. The land rock depicts the extensive boat voyages that spanned thousands of miles around the Australian cost line. The north-west monsoon, which arrived each December, also dictated the semi-permanent locations where the Makassan people would settle. These images likely contribute to narrative stories, which are associated with the ancestral story telling tradition of the indigenous people of Arnhem Land. Artist Nandabitta Maminyamandja (1911 - 1981) of the Anindilyakwa people painted Macassan prau and trepang curing in 1974. This work is natural pigments on eucalyptus bark and is now on display in the National Gallery of Australia. The subject matter includes the communication that the trepanging industry fostered, most importantly early trade interactions. In 1883, the trepanging trade started to decline with the South Australian governments implementation of the trepanging license. Trepanging-related art work was consistent with the influx of missionaries into the area, as there was a greater demand for secular stories. The missionaries did not encourage the production of ceremonial stories, and they established clear regulations around the subject matter that was depicted and distributed.
The chloroplasts of plant and algal cells can orient themselves to best suit the available light. In low-light conditions, they will spread out in a sheet—maximizing the surface area to absorb light. Under intense light, they will seek shelter by aligning in vertical columns along the plant cell's cell wall or turning sideways so that light strikes them edge-on. This reduces exposure and protects them from photooxidative damage. This ability to distribute chloroplasts so that they can take shelter behind each other or spread out may be the reason why land plants evolved to have many small chloroplasts instead of a few big ones. Chloroplast movement is considered one of the most closely regulated stimulus-response systems that can be found in plants. Mitochondria have also been observed to follow chloroplasts as they move. In higher plants, chloroplast movement is run by phototropins, blue light photoreceptors also responsible for plant phototropism. In some algae, mosses, ferns, and flowering plants, chloroplast movement is influenced by red light in addition to blue light, though very long red wavelengths inhibit movement rather than speeding it up. Blue light generally causes chloroplasts to seek shelter, while red light draws them out to maximize light absorption. Studies of Vallisneria gigantea, an aquatic flowering plant, have shown that chloroplasts can get moving within five minutes of light exposure, though they don't initially show any net directionality.
Sources: en.wikipedia.org
=== Block copolymer-mediated method === An economical, environmentally benign and fast synthesis methodology for gold nanoparticles using block copolymer has been developed by Sakai et al. In this synthesis methodology, block copolymer plays the dual role of a reducing agent as well as a stabilizing agent. The formation of gold nanoparticles comprises three main steps: reduction of gold salt ion by block copolymers in the solution and formation of gold clusters, adsorption of block copolymers on gold clusters and further reduction of gold salt ions on the surfaces of these gold clusters for the growth of gold particles in steps, and finally its stabilization by block copolymers. But this method usually has a limited-yield (nanoparticle concentration), which does not increase with the increase in the gold salt concentration. Ray et al. improved this synthesis method by enhancing the nanoparticle yield by manyfold at ambient temperature.
=== EC 1.5.1 With NAD+ or NADP+ as acceptor === EC 1.5.1.1: 1-piperideine-2-carboxylate/1-pyrroline-2-carboxylate reductase (NAD(P)H) EC 1.5.1.2: pyrroline-5-carboxylate reductase EC 1.5.1.3: dihydrofolate reductase EC 1.5.1.4: Now included with EC 1.5.1.3 dihydrofolate reductase EC 1.5.1.5: methylenetetrahydrofolate dehydrogenase (NADP+) EC 1.5.1.6: formyltetrahydrofolate dehydrogenase EC 1.5.1.7: saccharopine dehydrogenase (NAD+, L-lysine-forming) EC 1.5.1.8: saccharopine dehydrogenase (NADP+, L-lysine-forming) EC 1.5.1.9: saccharopine dehydrogenase (NAD+, L-glutamate-forming) EC 1.5.1.10: saccharopine dehydrogenase (NADP+, L-glutamate-forming) EC 1.5.1.11: D-octopine dehydrogenase EC 1.5.1.12: Now EC 1.2.1.88, L-glutamate γ-semialdehyde dehydrogenase EC 1.5.1.13: Now EC 1.17.1.5, nicotinate dehydrogenase EC 1.5.1.14: Now included with EC 1.5.1.21 Δ1-piperideine-2-carboxylate reductase EC 1.5.1.15: methylenetetrahydrofolate dehydrogenase (NAD+) EC 1.5.1.16: D-lysopine dehydrogenase EC 1.5.1.17: alanopine dehydrogenase EC 1.5.1.18: ephedrine dehydrogenase EC 1.5.1.19: D-nopaline dehydrogenase EC 1.5.1.20: methylenetetrahydrofolate reductase (NAD(P)H) EC 1.5.1.21: 1-piperideine-2-carboxylate/1-pyrroline-2-carboxylate reductase (NADPH) EC 1.5.1.22: strombine dehydrogenase EC 1.5.1.23: tauropine dehydrogenase EC 1.5.1.24: N5-(carboxyethyl)ornithine synthase EC 1.5.1.25: thiomorpholine-carboxylate dehydrogenase EC 1.5.1.26: β-alanopine dehydrogenase EC 1.5.1.27: 1,2-dehydroreticulinium reductase (NADPH) EC 1.5.1.28: opine dehydrogenase EC 1.5.1.29: Now covered by EC 1.5.1.38 [FMN reductase (NADPH)], EC 1.5.1.39 [FMN reductase [NAD(P)H])] and EC 1.5.1.41 (riboflavin reductase [NAD(P)H]) EC 1.5.1.30: flavin reductase (NADPH) EC 1.5.1.31: berberine reductase EC 1.5.1.32: vomilenine reductase EC 1.5.1.33: pteridine reductase EC 1.5.1.34: 6,7-dihydropteridine reductase EC 1.5.1.35: identical to EC 1.2.1.19, aminobutyraldehyde dehydrogenase, as the substrates 1-pyrroline and 4-aminobutanal are interconvertible EC 1.5.1.36: flavin reductase (NADH) EC 1.5.1.37: FAD reductase (NADH) EC 1.5.1.38: FMN reductase (NADPH) EC 1.5.1.39: FMN reductase (NAD(P)H) EC 1.5.1.40: 8-hydroxy-5-deazaflavin:NADPH oxidoreductase EC 1.5.1.41: riboflavin reductase (NAD(P)H) EC 1.5.1.42: FMN reductase (NADH) EC 1.5.1.43: carboxynorspermidine synthase EC 1.5.1.44: festuclavine dehydrogenase EC 1.5.1.45: FAD reductase (NAD(P)H) EC 1.5.1.46: agroclavine dehydrogenase EC 1.5.1.47: dihydromethanopterin reductase [NAD(P)+] EC 1.5.1.48: 2-methyl-1-pyrroline reductase EC 1.5.1.49: 1-pyrroline-2-carboxylate reductase [NAD(P)H] EC 1.5.1.50: dihydromonapterin reductase EC 1.5.1.51: N-[(2S)-2-amino-2-carboxyethyl]-L-lutamate dehydrogenase EC 1.5.1.52: staphylopine dehydrogenase EC 1.5.1.53: methylenetetrahydrofolate reductase (NADPH) EC 1.5.1.54: methylenetetrahydrofolate reductase (NADH)
=== Connective Tissue === The apical foramen is lined by connective tissue that is loosely organised, in which is continuous with the dental pulp and periodontal ligament. This tissue contains fibroblasts, collagen fibres, blood vessels and nerve fibres, as well as occasional immune cells such as macrophages. There is no epithelium in the apical foramen.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。