BDNF expression 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.
Last reviewed on 2025-12-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
纯度评估以反相高效液相色谱为主，通过主峰面积百分比给出粗略结果，再配合电喷雾质谱核对分子量。氨基酸分析可验证组成比例，手性色谱或毛细管电泳用于检查残基构型。常见杂质包括缺失序列的短肽、氧化产物与二聚体。由于多数市售品不附带完整检验报告，独立第三方检测常被用来核实标称值。
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
=== Function in pregnancy === During pregnancy, the production of prolactin by the mother increases steadily, starting at 6–8 weeks of gestation and continuing until the end of the pregnancy. Prolactin levels in the human fetal circulation see a gradual increase from around 30 weeks of gestation until birth. Prolactin is released into milk at amounts consistent with the typical circulating concentration. By the twentieth week of gestation, mammary glands have reached a sufficient level of development to generate milk components as a result of stimulation by prolactin. Post-lactational involution refers to the process of breast tissue returning to its normal state after milk production stops due to a decrease in prolactin levels.
Most penetrating injuries are chest wounds and have a mortality rate (death rate) of under 10%. Penetrating chest trauma can injure vital organs such as the heart and lungs and can interfere with breathing and circulation. Lung injuries that can be caused by penetrating trauma include pulmonary laceration (a cut or tear) pulmonary contusion (a bruise), hemothorax (an accumulation of blood in the chest cavity outside of the lung), pneumothorax (an accumulation of air in the chest cavity) and hemopneumothorax (accumulation of both blood and air). Sucking chest wounds and tension pneumothorax may result. Penetrating trauma can also cause injuries to the heart and circulatory system. When the heart is punctured, it may bleed profusely into the chest cavity if the membrane around it (the pericardium) is significantly torn, or it may cause pericardial tamponade if the pericardium is not disrupted. In pericardial tamponade, blood escapes from the heart but is trapped within the pericardium, so pressure builds up between the pericardium and the heart, compressing the latter and interfering with its pumping. Fractures of the ribs commonly produce penetrating chest trauma when sharp bone ends pierce tissues.
South Africa manufactured several complete nuclear weapons in the 1980s, but during the 1990s, it became the only country to eliminate its domestically produced nuclear arsenal, and abandon further nuclear weapon production. Nuclear weapons have been detonated on over 2,000 occasions for various testing purposes. Countries have increased their readiness to carry out strategic and tactical nuclear attacks in response to intensifying conflicts, including the Korean War, First and Second Taiwan Strait Crises, Cuban Missile Crisis, Vietnam War, Sino-Soviet border conflict, Yom Kippur War, Gulf War, and Russo-Ukrainian war. The 1962 Cuban Missile Crisis, between the nuclear superpowers of the U.S. and Soviet Union, is often considered the closest call with a nuclear exchange and possible World War III. Additionally, nuclear attack early warning systems have sometimes produced false alarms, increasing the risk of nuclear war, such as Soviet satellites in 1983 and Russian radar in 1995. After the dissolution of the Soviet Union in 1991 and the resultant end of the Cold War, the threat of a major nuclear war between the U.S. and Soviet Union has declined. Concern shifted to the prevention of localized nuclear conflicts resulting from nuclear proliferation, and the threat of nuclear terrorism. However, the threat of nuclear war is considered to have resurged since the start of the current phase of the Russo-Ukrainian war in 2022, particularly with regard to Russian threats to use nuclear weapons during the war.
=== Systems biology and systems medicine === Beginning in the 1990s, Hood focused more on cross-disciplinary biology and systems biology. He established in 1992 the first cross-disciplinary biology department, the Molecular Biotechnology Department at the University of Washington. In 2000, he co-founded the Institute for Systems Biology (ISB) in Seattle, Washington to develop strategies and technologies for systems approaches to biology and medicine. He co-led the Hood-Price research lab at ISB with Nathan Price until Price left to join Center for Human Healthspan at the Buck Institute for Research on Aging. Hood pioneered the systems biology concept of considering human biology as a "network of networks." In this model, understanding how systems function requires knowledge of: (1) the components of each network (including genetic, molecular, cellular, organ networks), (2) how these networks inter- and intra-connect, (3) how the networks change over time and undergo perturbations, and (4) how function is achieved within these networks. At the ISB under Hood's direction, genomic, transcriptomic, metabolomic and proteomic technologies are used to understand the "network of networks" and are focused on diverse biological systems (e.g. yeast, mice and humans). Hood applies the notion of systems biology to the study of medicine, specifically to cancer and neurodegenerative disease.
Sources: en.wikipedia.org
21°Bx = 200 mg N/L 23°Bx = 250 mg N/L 25°Bx = 300 mg N/L 27°Bx = 350 mg N/L However, other studies have shown successful fermentation be conducted with YAN levels below these recommendations as well as sluggish/stuck fermentations occurring even when YAN levels are in line with recommendations.
Bergamot essential oil (pronounced ), is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavouring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note.
== Applications == Freeze-drying (lyophilization) cycle development and optimization for pharmaceuticals. Flow diagnostics in hypersonic/re-entry speed research facilities and scramjet combustors. Oxygen tunable diode laser spectrometers play an important role in safety applications in a wide range of industrial processes, for this reason, TDLS are often an integral part of modern chemical plants. The fast response time compared to other technologies for measuring gas composition, and the immunity to many background gasses and environmental conditions makes TDL technology a commonly selected technology for monitoring of combustible gasses in process environments. This technology is employed on flares, in vessel headspace and in other locations where explosive atmospheres must be prevented from forming. According to a 2018 research study, TDL technology is the 4th most commonly selected technology for gas analysis in Chemical Processing.
Sources: en.wikipedia.org
=== Cost === In a 2020 cost-effectiveness study dupilumab was inferior to endoscopic sinus surgery (ESS): At a 36-year time horizon dupilumab treatment cost $536,420.22 and produced 8.95 QALYs (quality-adjusted life years), while ESS cost roughly one tenth at $50,436.99 and produced 9.80 QALYs.
September 15: Konrad Adenauer becomes the first Chancellor of the Federal Republic of Germany. October 1: Mao Zedong declares the foundation of the People's Republic of China, adding a quarter of the world's population to the communist camp. October 7: The Soviets declare their zone of Germany to be the German Democratic Republic, with its capital at East Berlin. October 16: Nikos Zachariadis, leader of the Communist Party of Greece, declares an end to the armed uprising. The declaration brings to a close the Greek Civil War, and the first successful containment of communism. December 27: Sovereignty of Indonesia is handed over to United States of Indonesia from the Netherlands following the Dutch-Indonesian Round Table Conference with Sukarno as the first president of the newly formed federation.
== Shelf-life and safety == The purpose of IMF foods is to achieve a water activity that the food can be stored safely without refrigeration. However, the food is not sterile. Staphylococcus aureus is a microorganism of concern as it can grow and produce specific enterotoxins in water activities of 0.83-0.86 under aerobic conditions. Because of this, proper handling, storage, hygiene and good manufacturing practices are necessary to prevent Staphylococcus aureus. Molds of Aspergillis and Penicillium species can grow and produce harmful mycotoxins at water activity 0.77-0.85. Salmonella and Bacillus cereus are the primary pathogens of concern with low-moisture foods and IMFs. Most illnesses associated with low-moisture foods or IMFs have been caused by Salmonella spp. To reduce the risk of bacterial growth, products are treated with a combination of low pH, addition of sugar, salt and preservatives, and a thermal process that can eliminate pathogens and extend shelf-life. In the case of yeasts and molds, chemical preservatives such as sorbates and propionates are used to inhibit their growth.
Sources: en.wikipedia.org
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
Semax is based on the ACTH(4-10) fragment, a seven-amino-acid segment of adrenocorticotropic hormone. The synthetic peptide retains the core sequence while removing regions associated with endocrine activity. This modification is intended to isolate effects on the nervous system.