This is a working overview of MC4 receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-04-14 and is reviewed periodically as new material appears.
Semax 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
Identity and purity are commonly assessed by reversed-phase high-performance liquid chromatography, with ultraviolet detection near 214 nanometers for the peptide backbone. Mass spectrometry, either electrospray or matrix-assisted laser desorption, confirms molecular mass and detects truncation or modification products. Amino acid analysis can verify composition. Because the sequence contains no strongly absorbing aromatic residue apart from phenylalanine, detection wavelengths are chosen carefully. Purity values above 95 percent are typical for research-grade material.
Quality documentation for research-grade peptide usually includes a certificate of analysis stating purity, identity, and residual counterion content. Batch-to-batch variation in purity and salt form is a recognized issue, and comparisons across suppliers require attention to the exact counterion, for example acetate versus trifluoroacetate. Sequence verification by tandem mass spectrometry provides stronger evidence than a single mass measurement. For any study reporting biological results, the analytical method and the measured purity should be stated explicitly. Independent verification of supplier claims is considered good practice.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
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.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
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.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
An RF value will always be in the range 0 to 1; if the substance moves, it can only move in the direction of the solvent flow, and cannot move faster than the solvent. For example, if particular substance in an unknown mixture travels 2.5 cm and the solvent front travels 5.0 cm, the retardation factor would be 0.50. One can choose a mobile phase with different characteristics (particularly polarity) in order to control how far the substance being investigated migrates. An RF value is characteristic for any given compound (provided that the same stationary and mobile phases are used). It can provide corroborative evidence as to the identity of a compound. If the identity of a compound is suspected but not yet proven, an authentic sample of the compound, or standard, is spotted and run on a TLC plate side by side (or on top of each other) with the compound in question. Note that this identity check must be performed on a single plate, because it is difficult to duplicate all the factors which influence RF exactly from experiment to experiment.
=== Handling === Embrittlement is a risk for many human remains, and as a result handling should be limited. When possible, artifacts should be lifted by their storage container or tray. To avoid transfer of oils to the remains, nitrile or latex gloves should be worn during their handling. If a body is to be lifted, it must be supported under all of its appendages.
In October 2023, Newsom vetoed several bills aimed at expanding access to housing assistance including the California Social Housing Act. One was a bill to repurpose unused state-owned land for affordable housing, which he said infringed on state sovereignty. Another would have expanded the number of people who qualify for state housing assistance. A third would have mandated that Medi-Cal cover the cost of housing assistance. Newsom has signed the Abundant and Affordable Homes Near Transit Act, Affordable Housing on Faith and Higher Education Lands Act, California Assembly Bill 2097 (2022) and California HOME Act. In August 2024, Newsom warned counties that did not remove their homeless encampments that failure to do so would result in their state funding being cut off the next year. He issued this warning after personally visiting and clearing out a Los Angeles homeless encampment without notifying the city beforehand. In September 2024, Newsom vetoed Assembly Bill 1840, which sought to prohibit the disqualification of applicants to California Housing Finance Agency home purchase assistance programs based solely on their immigration status.
Sources: en.wikipedia.org
Self-injurious and other behaviors are best managed by a combination of medical, physical, and behavioral interventions. The self-mutilation is often reduced by using restraints. Sixty percent of individuals have their teeth extracted in order to avoid self-injury, which families have found to be an effective management technique. Alternative dental treatments include the use of bite plates, lip bumpers, and mouthguards. Because stress increases self-injury, behavioral management through aversive techniques (which would normally reduce self-injury) actually increases self-injury in individuals with LNS. Nearly all affected individuals need restraints to prevent self-injury, and are restrained more than 75% of the time. This is often at their own request, and occasionally involves restraints that would appear to be ineffective, as they do not physically prevent biting. Families report that affected individuals are more at ease when restrained. The Matheny Medical and Educational Center Matheny | A Non-profit Organization for People with Special Needs in Peapack, NJ, has six Lesch–Nyhan syndrome patients, believed to be the largest concentration of LNS cases in one location, and is recognized as the leading source of information on care issues. Treatment for LNS patients, according to Gary E. Eddey, MD, medical director, should include: 1) Judicious use of protective devices; 2) Utilization of a behavioral technique commonly referred to as 'selective ignoring' with redirection of activities; and 3) Occasional use of medications.
=== Health care === Wittman opposes the Affordable Care Act and has voted to repeal it. He said that Congress should not merely be "anti-Obamacare" and that congressional Republicans are ready to provide alternatives if it is deemed unconstitutional. In 2017, he voted for the American Health Care Act, which would have repealed and replaced the ACA.
=== Safety === Like for other radioactive imaging agents in medicine, the applied amounts of radioactivity are so low that radiation-related adverse effects are very unlikely to occur, and have not been observed in practice. Consistent with the "tracer principle", the amount of pharmacologically active compound injected to a patient in the course of such an examination is extremely low. Adverse events, such as toxicity or allergic reactions, are thus highly improbable. No adverse or clinically detectable pharmacologic effects were observed following intravenous administration of 68Ga-Trivehexin when administered to cancer patients, and there were no significant changes in vital signs, laboratory study results, or electrocardiograms. In a study involving healthy volunteers, researchers again reported no adverse or clinically detectable pharmacologic effects and no significant changes in vital signs.
Sources: en.wikipedia.org
不是。Semax 是完全人工合成的七肽，自然界中没有对应的已知肽段。它的设计灵感来自促肾上腺皮质激素片段 ACTH(4-10)，但序列经过了替换和延长。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.