This is a working overview of BDNF expression, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-27. Anything still debated is marked as such rather than presented as settled.
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。
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
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.
== Contraindications == Oclacitinib is not labeled for use in dogs younger than one year due to reports of it causing demodicosis. It should also be avoided in dogs less than 3 kg (6.6 lb). Most of the other contraindications are avoiding cases where a potential side effect exacerbates a pre-existing condition: for example, because oclacitinib can cause lumps or tumors, it should not be used in dogs with cancer or a history of it; because it is an immune system suppressant, it should not be used in dogs with serious infections. Oclacitinib, by virtue of its low plasma protein binding, has little chance of reacting with other drugs. Nonetheless, concurrent use of steroids and oclacitinib has not been tested and is thus not recommended.
Extraperitoneal fascia (also: endoabdominal fascia or subperitoneal fascia) is a fascial plane – consisting mostly of loose areolar connective tissue – situated between the fascial linings of the walls of the abdominal and pelvic cavities (transversalis fascia, anterior layer of thoracolumbar fascia, iliac fascia, and psoas fascia) externally, and the parietal peritoneum internally. Its quality and quantity varies considerably. It occupies the extraperitoneal space.
== See also == Protein serine/threonine phosphatase, enzyme for reverse process. Pseudokinase, a protein without enzyme activity (pseudoenzyme). It can be related to proteins of this class. ATM serine/threonine kinase, responsible for the disorder ataxia–telangiectasia.
Sources: en.wikipedia.org
==== American Federation of Government Employees v. Trump ==== A lawsuit was filed on February 6, 2025, by the American Foreign Service Association and the American Federation of Government Employees in the US District Court for the District of Columbia, requesting a temporary restraining order and preliminary injunction against the administration, claiming that it violated separation of powers, the Take Care Clause of the Constitution, and the Administrative Procedure Act and requesting that all attempts to shut down the agency be halted, all recent actions be reversed, and a new acting director be appointed. The following day, U.S. District Judge Carl Nichols, nominated by President Trump in 2019, stated from the bench that he would enter in a "temporary restraining order", pausing the plan to put thousands of employees on leave and pausing the accelerated removal of workers from their posts abroad. On February 21, 2025, Judge Nichols cleared the way for the Trump administration to move forward with pulling thousands of USAID staffers off the job in the United States and around the world, as part of an administration plan to also provide those abroad with a 30-day deadline to move back to the U.S. at government expense. Nichols had previously argued that Trump's actions threaten the safety of USAID workers abroad because many are deployed in unstable regions.
=== Alzheimer's Disease === In contrary, big dynorphin exhibits neuroprotective properties against amyloid-β (Aβ) accumulation in Alzheimer's disease. It reduces the hydrophobicity and slows the aggregation kinetics of Aβ40, the most abundant amyloid species, resulting in around 2-fold reduction in amyloid aggregation compared to Aβ alone. In human neuroblastoma cell cultures, big dynorphin pre-incubated with Aβ40 significantly increased cell viability to compared to Aβ40 alone. The neuroprotective mechanism involves big dynorphin's cationic amino acid residues stabilizing negatively charged regions of Aβ, preventing the β-sheet transition and maintaining Aβ in an α-helical conformation. These findings suggest therapeutic potential for big dynorphin-derived peptides in Alzheimer's disease treatment.
Breastfeeding Resources – La Leche League International (archived 6 November 2006) "Breast-Feeding Content Resources" – WHO reports on Breast Feeding "Breastfeeding and Breast Milk" – US National Institute of Health Center for Disease Control and Prevention Breastfeeding Academy of Breastfeeding Medicine The World Alliance for Breastfeeding Action LactMed – a database of the safety of drugs to which breastfeeding mothers may be exposed by the US National Library of Medicine
Sources: en.wikipedia.org
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.