neurotrophic signaling 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.
Updated 2025-09-19. Numbers and descriptions here follow the published literature rather than marketing material.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary research models | Rodent studies | Largest share of published data |
| Reported markers | BDNF and NGF expression | Measured mainly in animal tissue |
| Common administration | Intranasal | Matches the registered formulation |
| Blood residence time | Minutes | Rapid enzymatic degradation |
| Evidence quality | Small trials, limited replication | Noted repeatedly in reviews |
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Gag-onc fusion protein Bcr-abl fusion protein Tpr-met fusion protein Antibodies are fusion proteins produced by V(D)J recombination. There are also rare examples of naturally occurring polypeptides that appear to be a fusion of two clearly defined modules, in which each module displays its characteristic activity or function, independent of the other. Two major examples are: double PP2C chimera in Plasmodium falciparum (the malaria parasite), in which each PP2C module exhibits protein phosphatase 2C enzymatic activity, and the dual-family immunophilins that occur in a number of unicellular organisms (such as protozoan parasites and Flavobacteria) and contain full-length cyclophilin and FKBP chaperone modules. The evolutionary origin of such chimera remains unclear.
Spyrakis et al. relied on a workflow of MD simulations, fingerprints for ligands and proteins (FLAP) and linear discriminant analysis (LDA) to identify the best ligand-protein conformations to act as pharmacophore templates based on retrospective ROC analysis of the resulting pharmacophores. In an attempt to ameliorate structure-based drug discovery modeling, vis-à-vis the need for many modeled compounds, Hatmal et al. proposed a combination of MD simulation and ligand-receptor intermolecular contacts analysis to discern critical intermolecular contacts (binding interactions) from redundant ones in a single ligand–protein complex. Critical contacts can then be converted into pharmacophore models that can be used for virtual screening. An important factor is intramolecular hydrogen bonds, which are not explicitly included in modern force fields, but described as Coulomb interactions of atomic point charges. This is a crude approximation because hydrogen bonds have a partially quantum mechanical and chemical nature. Furthermore, electrostatic interactions are usually calculated using the dielectric constant of a vacuum, even though the surrounding aqueous solution has a much higher dielectric constant. Thus, using the macroscopic dielectric constant at short interatomic distances is questionable. Finally, van der Waals interactions in MD are usually described by Lennard-Jones potentials based on the Fritz London theory that is only applicable in a vacuum.
The Legislative Reorganization Act of 1970 renewed emphasis for the library on its legislative roles, requiring a greater focus on research for Congress and congressional committees, and renaming the Legislative Reference Service as the Congressional Research Service.
Humans have known about the heart since ancient times, although its precise function and anatomy were not clearly understood. From the primarily religious views of earlier societies towards the heart, ancient Greeks are considered to have been the primary seat of scientific understanding of the heart in the ancient world. Aristotle considered the heart to be the organ responsible for creating blood; Plato considered the heart as the source of circulating blood and Hippocrates noted blood circulating cyclically from the body through the heart to the lungs. Erasistratos (304–250 BCE) noted the heart as a pump, causing dilation of blood vessels, and noted that arteries and veins both radiate from the heart, becoming progressively smaller with distance, although he believed they were filled with air and not blood. He also discovered the heart valves. The Greek physician Galen (2nd century CE) knew blood vessels carried blood and identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Galen, noting the heart as the hottest organ in the body, concluded that it provided heat to the body. The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves. Galen believed the arterial blood was created by venous blood passing from the left ventricle to the right through 'pores' between the ventricles. Air from the lungs passed from the lungs via the pulmonary artery to the left side of the heart and created arterial blood.
The bite is immediately followed by the local pain of a burning character; the limb soon swells and becomes discolored, and within one to three hours great prostration, accompanied by vomiting, and often diarrhea, sets in. Cold, clammy perspiration is usual. The pulse becomes extremely feeble, and slight dyspnoea and restlessness may be seen. In severe cases, which occur mostly in children, the pulse may become imperceptible and the extremities cold; the patient may pass into coma. In from twelve to twenty-four hours these severe constitutional symptoms usually pass off; but in the meantime, the swelling and discoloration have spread enormously. The limb becomes phlegmonous and occasionally suppurates. Within a few days recovery usually occurs somewhat suddenly, but death may result from the severe depression or from the secondary effects of suppuration. That cases of death, in adults as well as in children, are not infrequent in some parts of the Continent is mentioned in the last chapter of this Introduction. The Viperidae differ much among themselves in the toxicity of their venoms. Some, such as the Indian Russell's viper (Daboia russelli) and saw-scaled viper (E. carinatus); the American rattlesnakes (Crotalus spp.), bushmasters (Lachesis spp.), and lanceheads (Bothrops spp.); and the African adders (Bitis spp.), night adders (Causus spp.), and horned vipers (Cerastes spp.), cause fatal results unless a remedy is speedily applied.
Sources: en.wikipedia.org
The IGFs are known to bind the IGF-1 receptor, the insulin receptor, the IGF-2 receptor, the insulin-related receptor and possibly other receptors. The IGF-1 receptor is the "physiological" receptor. IGF-1 binds to it at significantly higher affinity than it binds the insulin receptor. Like the insulin receptor, the IGF-1 receptor is a receptor tyrosine kinase—meaning the receptor signals by causing the addition of a phosphate molecule on particular tyrosines. The IGF-2 receptor only binds IGF-2 and acts as a "clearance receptor"—it activates no intracellular signaling pathways, functioning only as an IGF-2 sequestering agent and preventing IGF-2 signaling.
=== Psychological effects === LSD can induce panic attacks or extreme anxiety, colloquially termed a "bad trip". Despite lower rates of depression and substance abuse found in psychedelic drug users compared to controls, LSD presents a heightened a risk of hallucinogen-induced psychotic disorder for individuals with mental illnesses such as bipolar disorder or schizophrenia or who have a family history of those illnesses. It is common for people with pre-existing mental illness to be hospitalized for hallucinogen-induced psychotic disorder caused by LSD. LSD is also the main cause of hallucinogen persisting perception disorder (HPPD), where visual distortions persist beyond the initial effects of the drug.
=== Modern times === The university hired its first African-American faculty member, Vivian Cox, in 1967. Three professors were murdered at the school in a shooting in 2002. The perpetrator, who then shot himself, was a student who had failed out of the school. He mailed a 22-page letter to the Arizona Daily Star announcing his reasons, naming two of the killed professors in the letter; following the shooting, the Daily Star made the controversial decision to publish the letter. On April 17, 2020, the University of Arizona announced temporary pay cuts and furloughs to its 15,000 employees as its Tucson campus shut down due to the COVID-19 pandemic. All employees making up to $150,000 per year were furloughed, with the length determined by each employees' salary. For employees making more than $150,000 per year, pay cuts of 17% or 20% were instituted. Also in 2020, the University of Arizona announced it had purchased Ashford University from Zovio and renamed it The University of Arizona Global Campus. The purchase was heavily criticized, particularly by University of Arizona faculty members. As Ashford was being purchased by the University of Arizona, it was the subject of an investigation by the Attorney General of Massachusetts, a lawsuit from the Attorney General of California, and a formal notification of concern from the university's accreditor. A university professor was murdered on campus in October 2022, by a former student. Following the crime, the university commissioned an independent investigation of campus safety.
== External links == Clinical trial number NCT02608450 for "A Study to Evaluate the Safety and Efficacy of CB-03-01 Cream, 1% in Subjects With Facial Acne Vulgaris (25)" at ClinicalTrials.gov Clinical trial number NCT02608476 for "A Study to Evaluate the Safety and Efficacy of CB-03-01 Cream, 1% in Subjects With Facial Acne Vulgaris (26)" at ClinicalTrials.gov
21 May The WHO informs about the international 2022 monkeypox outbreak in non-endemic countries – an unprecedented number of cases detected outside of Africa after the first of these cases was detected on 6 May. On 24 May, the WHO states that the outbreak can be contained. The main method used for the early containment is 'ring vaccination' – vaccinating close contacts of positive cases via existing vaccines. 23 May Researchers report that CRISPR-Cas9 gene editing has been used to boost vitamin D in tomatoes. A study shows why decarbonization must be accompanied by strategies to reduce the levels of short-lived climate pollutants with near-term effects for climate goals. 24 May Scientists report the first 3D-printed lab-grown wood. It is unclear if it could ever be used on a commercial scale (e.g. with sufficient production efficiency and quality). A CDC study based on electronic health records shows that "one in five COVID-19 survivors aged 18–64 years and one in four survivors aged ≥65 years experienced at least one incident condition that might be attributable to previous COVID-19" or long COVID. On 18 May, an analysis of private healthcare claims shows that of 78,252 patients diagnosed with 'long COVID', 75.8% had not been hospitalized for COVID-19. 25 May – The world's smallest remote-controlled walking robot, measuring just half a millimetre wide, is demonstrated. Potential applications include the clearing of blocked arteries.
Sources: en.wikipedia.org
The main proposal is modulation of neurotrophic factors such as brain-derived neurotrophic factor, supported largely by animal experiments. Receptor-level targets have not been firmly established. Most reviews describe the mechanism as only partially characterized.
The compound is registered as a medicine in Russia, so clinical work has concentrated there. Trials elsewhere are few and generally small. This geographic concentration is a recognized limitation in evidence reviews.
Some fraction may reach the central nervous system through olfactory pathways, and this is often cited as the rationale for the nasal route. The size of that fraction in humans is not well quantified. Blood concentrations after nasal dosing are low, which complicates measurement.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.