If you have been reading about Pro-Gly-Pro tail and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-09-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide (ACTH fragment analog) | Not a steroid; does not belong to the melanocortin agonist drugs by marketing category |
| Molecular formula | C37H51N9O10S (commonly cited) | Reported values vary slightly with salt and counter-ion content |
| Appearance | White to off-white lyophilized powder | A single batch may appear as a loose cake or fluffy solid |
| Solubility | Freely soluble in water and aqueous buffer | Stock solutions are usually prepared in sterile water or saline |
| Typical storage | −20 °C or below, desiccated and protected from light | Seal opened vials promptly to limit moisture uptake |
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
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.
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.
Signs of androgen excess, either clinical (visible signs such as facial hair or acne) or biochemical (detected through a blood test). Androgens are "male" hormones like testosterone. Irregular or absent menstrual cycles Polycystic ovaries on ultrasound or high levels of anti-Müllerian hormone (AMH) Other causes of these issues need to be excluded for diagnosis. In adolescents, both androgen excess and irregular or absent periods are required, as it is normal for adolescents to have many follicles ("cysts") visible in their ovaries, so it does not help with diagnosis. Adolescents who only meet one criterion are considered 'at risk', and are to be reassessed when they are adults. Older criteria are the 1990 NIH criteria and the 2006 Androgen Excess Society criteria. The Androgen Excess Society criteria were never widely adopted. The old NIH criteria are stricter than the Rotterdam criteria, as both infrequent or irregular cycles and signs of androgen excess need to be present:
== Function == EGF, via binding to its cognate receptor, results in cellular proliferation, differentiation, and survival. Salivary EGF, which seems to be regulated by dietary inorganic iodine, also plays an important physiological role in the maintenance of oro-esophageal and gastric tissue integrity. The biological effects of salivary EGF include healing of oral and gastroesophageal ulcers, inhibition of gastric acid secretion, stimulation of DNA synthesis as well as mucosal protection from intraluminal injurious factors such as gastric acid, bile acids, pepsin, and trypsin and to physical, chemical and bacterial agents.
Nanoparticle drug delivery systems are engineered technologies that use nanoparticles for the targeted delivery and controlled release of therapeutic agents. The modern form of a drug delivery system should minimize side-effects and reduce both dosage and dosage frequency. Recently, nanoparticles have aroused attention due to their potential application for effective drug delivery. Nanomaterials exhibit different chemical and physical properties or biological effects compared to larger-scale counterparts that can be beneficial for drug delivery systems. Some important advantages of nanoparticles are their high surface-area-to-volume ratio, chemical and geometric tunability, and their ability to interact with biomolecules to facilitate uptake across the cell membrane. The large surface area also has a large affinity for drugs and small molecules, like ligands or antibodies, for targeting and controlled release purposes. Nanoparticles refer to a large family of materials both organic and inorganic. Each material has uniquely tunable properties and thus can be selectively designed for specific applications. Despite the many advantages of nanoparticles, there are also many challenges, including but not exclusive to: nanotoxicity, biodistribution and accumulation, and the clearance of nanoparticles by human body. The National Institute of Biomedical Imaging and Bioengineering has issued the following prospects for future research in nanoparticle drug delivery systems:
Calcitonin gene-related peptides (CGRP) are a group of two similar neuropeptides that belong to the calcitonin family. The two types of CGRP in humans are alpha-CGRP (α-CGRP, also known as CGRP I) and beta-CGRP (β-CGRP, also known as CGRP II). α-CGRP is a 37-amino acid neuropeptide formed by alternative splicing of the calcitonin/CGRP gene located on chromosome 11. β-CGRP is less studied. In humans, β-CGRP differs from α-CGRP by three amino acids and is encoded in a separate, nearby gene. The CGRP family includes calcitonin (CT), adrenomedullin (AM), and amylin (AMY).
=== Breathing === In December 2019, the US Food and Drug Administration (FDA) warned about serious breathing issues for those taking gabapentin or pregabalin when used with central nervous system (CNS) depressants or for those with lung problems. The FDA required new warnings about the risk of respiratory depression to be added to the prescribing information of the gabapentinoids. The FDA also required the drug manufacturers to conduct clinical trials to further evaluate their abuse potential, particularly in combination with opioids, because misuse and abuse of these products together is increasing, and co-use may increase the risk of respiratory depression. Among 49 case reports submitted to the FDA over the five-year period from 2012 to 2017, twelve people died from respiratory depression with gabapentinoids, all of whom had at least one risk factor. The FDA reviewed the results of two randomized, double-blind, placebo-controlled clinical trials in healthy people, three observational studies, and several studies in animals. One trial showed that using pregabalin alone and using it with an opioid pain reliever can depress breathing function. The other trial showed gabapentin alone increased pauses in breathing during sleep. The three observational studies at one academic medical center showed a relationship between gabapentinoids given before surgery and respiratory depression occurring after different kinds of surgeries. The FDA also reviewed several animal studies that showed pregabalin alone and pregabalin plus opioids can depress respiratory function.
Sources: en.wikipedia.org
== See also == Extension Poly(A) Test GeneCalling, an mRNA profiling technology Missense mRNA mRNA display mRNA surveillance Prokaryotic mRNA degradation Transcriptome, the sum of all RNA in a cell modRNA Nucleoside-modified messenger RNA
In the average person, the diaphragm should be intersected by the 5th to 7th anterior ribs at the mid-clavicular line, and 9 to 10 posterior ribs should be viewable on a normal PA inspiratory film. An increase in the number of viewable ribs implies hyperinflation, as can occur, for example, with obstructive lung disease or foreign body aspiration. A decrease implies hypoventilation, as can occur with restrictive lung disease, pleural effusions or atelectasis. Underexpansion can also cause interstitial markings due to parenchymal crowding, which can mimic the appearance of interstitial lung disease. Enlargement of the right descending pulmonary artery can indirectly reflect changes of pulmonary hypertension, with a size greater than 16 mm abnormal in men and 15 mm in women. Appropriate penetration of the film can be assessed by faint visualization of the thoracic spines and lung markings behind the heart. The right diaphragm is usually higher than the left, with the liver being situated beneath it in the abdomen. The minor fissure can sometimes be seen on the right as a thin horizontal line at the level of the fifth or sixth rib. Splaying of the carina can also suggest a tumor or process in the middle mediastinum or enlargement of the left atrium, with a normal angle of approximately 60 degrees. The right paratracheal stripe is also important to assess, as it can reflect a process in the posterior mediastinum, in particular the spine or paraspinal soft tissues; normally it should measure 3 mm or less.
=== Blood supply === The sinoatrial node receives its blood supply from the sinoatrial nodal artery. This blood supply, however, can differ hugely between individuals. For example, in most humans, this is a single artery, although in some cases there have been either 2 or 3 sinoatrial node arteries supplying the SA node. Also, the SA node artery mainly originates as a branch of the right coronary artery; however in some individuals it has arisen from the circumflex artery, which is a branch of the left coronary artery. Finally, the SA node artery commonly passes behind the superior vena cava, before reaching the SA node; however in some instances it passes in front. Despite these many differences, there doesn't appear to be any advantage to how many sinoatrial nodal arteries an individual has, or where they originate.
== External links == Sugimura T, Nagao M, Wakabayashi K (May 1996). "Carcinogenicity of food mutagens". Environmental Health Perspectives. 104 (Suppl 3): 429–33. doi:10.2307/3432798. JSTOR 3432798. PMC 1469643. PMID 8781358. Louis ED, Zheng W, Jiang W, Bogen KT, Keating GA (June 2007). "Quantification of the neurotoxic beta-carboline harmane in barbecued/grilled meat samples and correlation with level of doneness". Journal of Toxicology and Environmental Health, Part A. 70 (12): 1014–9. Bibcode:2007JTEHA..70.1014L. doi:10.1080/15287390601172015. PMC 4993204. PMID 17497412.
Sources: en.wikipedia.org
Pain: Sacral, coccygeal (tailbone), gluteal, groin, rectum, and perineal regions Sciatica and leg pain Foot and toe pain Persistent genital arousal disorder (PGAD) or pudendal neuralgia Neuropathic pain characterized by burning (dysesthesia), aching, or stabbing sensations Sensory Disturbances: Paresthesias such as tingling, electric shocks, buzzing or internal vibrations Fasciculations (muscle twitching) Numbness or other sensory deficits Motor Dysfunction: Muscle weakness (Paresis) in the legs and feet Toe cramping and muscle spasms Foot Drop (Rarely) Bladder, Bowel, Sexual Dysfunction: Neurogenic bladder: urinary retention, hesitation, Valsalva voiding, increased frequency and urgency, painful bladder, urge incontinence, and stress incontinence. Neurogenic bowel: constipation, diarrhea, cramping, urgency, changes in defecation frequency, false urge to defecate, fecal incontinence, anal sphincter pain or pressure. Erectile dysfunction; retrograde ejaculation Positional Aggravation: Symptoms are typically worsened by standing, walking, sitting, or bending Lying down (recumbency) may provide partial or temporary symptom relief
=== Off-label drugs === α2-Adrenergic receptor agonists (e.g., clonidine, tizanidine) Acetaminophen (paracetamol) Adenosine receptor antagonists (e.g., caffeine) Angiotensin-converting-enzyme inhibitors (ACE inhibitors) (e.g., lisinopril) Angiotensin receptor antagonists (e.g., candesartan, telmisartan) Antipsychotics and related (e.g., prochlorperazine, metoclopramide, haloperidol, promethazine, chlorpromazine) Anticonvulsants (e.g., valproic acid) Barbiturates (e.g., butalbital, proxibarbital) Beta blockers (β-adrenergic receptor antagonists) (e.g., propranolol, metoprolol, nadolol, timolol, atenolol) Calcium channel blockers (e.g., verapamil, nimodipine, nifedipine, diltiazem) Cannabinoids (cannabinoid receptor agonists) (e.g., cannabis, tetrahydrocannabinol (THC)) Corticosteroids (e.g., dexamethasone, prednisone) Ergoline monoamine receptor modulators (e.g., ergotamine, methylergometrine, methysergide, dihydroergocryptine, bromocriptine, lisuride) Estrogens (estrogen receptor agonists) (e.g., estradiol, ethinylestradiol) Gabapentinoids (α2δ subunit-containing volate-gated calcium channel ligands) (e.g., gabapentin, pregabalin) Melatonin Nonsteroidal anti-inflammatory drugs (NSAIDs; COX inhibitors) (e.g., ibuprofen, aspirin, naproxen, diclofenac, ketorolac, ketoprofen) Opioids (μ-opioid receptor agonists) (e.g., morphine, codeine, oxycodone, hydrocodone) Progestogens (progesterone receptor agonists) (e.g., progesterone, medroxyprogesterone acetate) Propofol Serotonergic psychedelics (e.g., psilocybin, lysergic acid diethylamide (LSD), dimethyltryptamine (DMT)) Serotonin receptor antagonists (e.g., methysergide, pizotifen, cyproheptadine) Sodium channel blockers (e.g., lidocaine) Tetracyclic antidepressants (TeCAs) (e.g., mianserin, mirtazapine) Tricyclic antidepressants (TCAs) (e.g., amitriptyline, nortriptyline, imipramine)
A Jarisch–Herxheimer reaction is a sudden and typically transient reaction that may occur within 24 hours of being administered antibiotics for an infection by a spirochete, including syphilis, leptospirosis, Lyme disease, and relapsing fever. Signs and symptoms include fever, chills, shivers, feeling sick, headache, fast heart beat, low blood pressure, breathing fast, flushing of skin, muscle aches, and worsening of skin lesions. It may sometimes be mistaken as an allergy to the antibiotic. Jarisch–Herxheimer reactions are usually self-limiting but severe presentations can be life-threatening if they cause a significant drop in blood pressure and cause acute end-organ injury, eventually leading to multi-organ failure.
Sources: en.wikipedia.org
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.
It was developed in the Soviet Union during the early 1980s by groups at the Institute of Molecular Genetics in Moscow. Russian approval for intranasal use followed, and it has been marketed there since. Western laboratories encountered it mainly through translated literature and, later, through online research-chemical trade.
It holds a Russian registration as a prescription nasal product but has no approval from the European Medicines Agency or the United States Food and Drug Administration. Buyers outside Russia usually receive material sold strictly for laboratory research. That distinction matters because research-grade and pharmaceutical-grade products carry different documentation and testing expectations.
It is a synthetic peptide of seven amino acids. Its backbone corresponds to a fragment of adrenocorticotropic hormone extended at the carboxyl end. The material is distributed as a lyophilized solid for laboratory use.