Semax is a synthetic heptapeptide analogue of ACTH(4-10) — sequence Met-Glu-His-Phe-Pro-Gly-Pro — developed at the Institute of Molecular Genetics in Russia during the 1980s and 1990s, and subsequently approved in Russia for neurological research applications including stroke intervention and cognitive deficit models. Unlike native ACTH fragments, Semax incorporates a C-terminal Pro-Gly-Pro extension that confers resistance to dipeptidyl peptidase IV (DPP-IV) enzymatic degradation, dramatically extending its biological half-life compared to unmodified ACTH(4-7) sequences. This structural modification — alongside Semax's documented capacity to upregulate Brain-Derived Neurotrophic Factor (BDNF) and modulate central monoamine systems — has made it one of the most extensively researched neuropeptides in the published preclinical neuroscience literature.
This article covers Semax's molecular structure, its relationship to the ACTH(4-7) analogue class, the published research on BDNF upregulation, neuroprotection models, cognitive research findings, and a comparison with its sister compound Selank. Researchers investigating neuropeptide-mediated cognitive biology may also find the Cognitive Focus Research Stack relevant for combined compound protocols. Semax 10MG is available from Pure Grade Labs for in vitro laboratory research purposes only.
All content reflects published preclinical and clinical research. For research purposes only. Not for human consumption.
Key Takeaways
- Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide derived from ACTH(4-10), developed in Russia and approved there for neurological research applications including stroke and cognitive deficit protocols.
- Its C-terminal Pro-Gly-Pro extension renders Semax resistant to DPP-IV enzymatic cleavage — a critical structural distinction from native ACTH(4-7) fragments, providing substantially greater metabolic stability and enabling intranasal bioavailability in research models.
- Published preclinical research documents that Semax upregulates BDNF (Brain-Derived Neurotrophic Factor) expression in rat brain tissue — a mechanism with significant implications for neuroplasticity and neuroprotection research (Dolotov et al., 2006).
- Research literature documents Semax's modulatory effects on central serotonin and dopamine systems, with published studies examining its influence on monoamine metabolism in key brain regions associated with attention, motivation, and stress response (Eremin et al., 2005).
- Ischaemia and neuroprotection models have shown Semax attenuates oxidative stress markers and supports neuronal survival in rodent stroke models (Gusev et al., 1997; Shadrina et al., 2010). Selank, its anxiolytic counterpart, is covered comparatively in the final section of this article.
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View Semax 10MG →What Is Semax?
Semax is a synthetic neuropeptide with the amino acid sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in the 1980s and 1990s as part of a broader programme investigating synthetic analogues of adrenocorticotropic hormone (ACTH) fragments for neurological applications. It was subsequently approved in Russia under the trade name Semax for use in neurological research contexts, including transient ischaemic attack intervention and cognitive impairment studies.
The compound is structurally derived from ACTH(4-10) — a seven-amino acid sequence within the larger 39-amino acid ACTH molecule. Critically, Semax retains the biologically active core sequence of ACTH(4-7) (Met-Glu-His-Phe) responsible for the peptide's CNS activity, while the Pro-Gly-Pro C-terminal extension stabilises the molecule against rapid enzymatic degradation. This architectural choice distinguishes Semax from earlier, less stable ACTH fragment analogues and is the primary reason for its utility as a research compound.
Importantly, Semax does not produce the adrenocortical effects of full-length ACTH — it lacks the receptor binding domain responsible for cortisol stimulation, meaning its CNS effects are mediated through distinct mechanisms independent of the HPA axis. This profile makes Semax particularly useful in research designs studying neuropeptide effects on brain function without the confounding variable of glucocorticoid elevation.
The ACTH(4-7) Analogue Mechanism: How Semax Differs from Native Peptides
To understand why Semax was engineered as it was, it is necessary to understand the pharmacological limitations of native ACTH fragments in CNS research.
The behavioural and neurological effects of ACTH were observed long before the specific active sequence was isolated. Early research established that ACTH's influence on learning, memory, and attention — observed in rodent models — did not require adrenocortical activation and could be replicated with much shorter fragments. The sequence ACTH(4-7) emerged as the minimal active core: Met-Glu-His-Phe. However, unmodified ACTH(4-7) has a severely limited biological half-life in vivo due to rapid cleavage by dipeptidyl peptidase IV (DPP-IV) at the N-terminal Met-Glu bond, as well as by other serum proteases. This rapid degradation made ACTH(4-7) impractical as a research tool requiring sustained CNS engagement.
Semax addresses this through two design choices: first, the Pro-Gly-Pro C-terminal extension creates a structural conformation that slows enzymatic recognition and cleavage; second, the molecule retains the Met N-terminus (rather than removing it as in some analogues), preserving potency at CNS targets while gaining metabolic stability. The result is a compound that demonstrates meaningful bioavailability via the intranasal route — a critical feature for CNS research, since intranasal administration enables peptide delivery directly via the olfactory pathway to bypass the blood-brain barrier.
The N-Pro (N-acetyl) Extension: Semax vs. Semax N-Pro
Researchers should note the distinction between standard Semax and its N-Pro (N-acetylated) variant. N-Pro Semax adds an N-terminal acetyl modification that further reduces DPP-IV cleavage at the Met position, providing even greater metabolic stability than standard Semax. Published research literature refers to both forms, though standard Semax remains the more extensively studied compound in the preclinical neuroscience corpus.
BDNF Upregulation: The Core Research Finding
The most consistently documented mechanism in the published Semax research literature is its capacity to upregulate Brain-Derived Neurotrophic Factor (BDNF) expression in rodent brain tissue. BDNF is a member of the neurotrophin family — signalling proteins that support neuronal survival, synaptic plasticity, and the formation and maintenance of neural circuits. It acts primarily via the TrkB (tropomyosin receptor kinase B) receptor and is widely considered one of the most important signalling molecules in learning, memory consolidation, and resilience to neurodegeneration.
A landmark study by Dolotov OV et al. (2006), published in Doklady Biochemistry and Biophysics, examined Semax's effects on BDNF expression in rat brain regions. The research documented that Semax administration was associated with statistically significant increases in BDNF mRNA expression in the hippocampus and frontal cortex — two regions with the highest BDNF density in rodent brain and the most direct relevance to cognitive and memory research. The authors proposed that Semax's BDNF-upregulatory effect may be one of the primary mechanisms underlying the neuroprotective and pro-cognitive findings documented in other Semax studies, given BDNF's role as a downstream mediator of neuroplasticity signalling via the TrkB/PI3K and TrkB/MAPK pathways.
BDNF upregulation has significant research implications beyond cognitive function alone. The neurotrophin is actively studied as a potential biomarker and therapeutic target in Alzheimer's disease, Parkinson's disease, major depressive disorder, and traumatic brain injury models — all conditions characterised by reduced BDNF signalling. Semax's documented capacity to upregulate BDNF expression in preclinical models makes it a research tool of broad relevance across the neuroscience literature, not exclusively within the cognitive enhancement research niche.
BDNF and Synaptic Plasticity: The Mechanistic Link
BDNF's role in synaptic plasticity operates primarily through long-term potentiation (LTP) — the sustained strengthening of synaptic connections that is the primary cellular mechanism underlying learning and memory formation. TrkB receptor activation by BDNF initiates a signalling cascade that increases AMPA receptor trafficking to the postsynaptic membrane, enhances glutamate release probability at presynaptic terminals, and promotes dendritic spine formation — all molecular events associated with durable synaptic strengthening. Semax-induced BDNF upregulation in the hippocampus and prefrontal cortex, as documented in preclinical models, represents a potential mechanism by which the compound's pro-cognitive research findings may be mechanistically explained.
Neuroprotection Research: Ischaemia and Neuronal Survival Models
Beyond cognitive research, a substantial body of published literature has examined Semax in neuroprotection models — particularly ischaemia (stroke), oxidative stress, and neurodegeneration. This research direction reflects Semax's approved clinical application in Russia for transient ischaemic attack intervention, and provides mechanistic context for the compound's broader neuroprotective properties.
Gusev EI et al. (1997), published in Cerebrovascular Diseases, examined Semax in patients with ischaemic stroke and documented favourable outcomes in neurological function recovery scores compared to control groups. While this early clinical data requires interpretation in the context of Russian regulatory standards and study design of the era, it established the primary translational rationale for Semax as a neuroprotective compound and informed subsequent, more mechanistically rigorous preclinical research.
More mechanistically detailed research was published by Shadrina MI et al. (2010) in the Journal of Molecular Neuroscience. This study examined Semax's effects on gene expression in rat brain following ischaemia, documenting that Semax modulated the expression of a cluster of genes associated with neuroprotection, anti-apoptotic signalling, and inflammatory response attenuation. Notably, the research found upregulation of genes involved in BDNF-TrkB signalling downstream pathways in ischaemia-exposed brain tissue treated with Semax, consistent with Dolotov et al.'s BDNF expression findings and suggesting a converging mechanistic picture: Semax's neuroprotective effects may be substantially mediated through BDNF-TrkB pathway activation.
Oxidative Stress Attenuation
Ischaemic neuronal death involves a secondary cascade of oxidative damage — reactive oxygen species (ROS) generated during reperfusion cause mitochondrial dysfunction, lipid peroxidation, and DNA damage in periinfarct neurons that were not directly killed by ischaemia itself. Published preclinical research has examined whether Semax administration attenuates this oxidative secondary injury cascade. Rodent models using middle cerebral artery occlusion (MCAO) — the standard preclinical ischaemia model — have documented reduced markers of oxidative stress in Semax-treated animals relative to controls, though the specific molecular targets mediating this effect remain an active area of preclinical investigation.
In a 2006 series of experiments described by Dolotov and colleagues, researchers administered Semax intranasally to adult Wistar rats and examined hippocampal tissue at 1, 3, and 24 hours post-administration. BDNF mRNA levels were elevated at all three time points relative to vehicle-treated controls, with the most pronounced increases in the CA1 and CA3 hippocampal subfields — regions with the densest BDNF expression and the highest documented vulnerability to ischaemic and excitotoxic injury. The researchers noted that the temporal profile of BDNF upregulation was consistent with Semax's intranasal bioavailability characteristics, suggesting olfactory-to-CNS delivery was achieving meaningful hippocampal peptide concentrations within the first hour of administration. The finding positioned Semax as one of a small number of intranasally deliverable compounds with documented central BDNF upregulation in published rodent research.
Cognitive Research Findings: Attention, Memory, and Learning Models
The published preclinical literature on Semax's cognitive research findings spans multiple domains: attention and sustained focus models, memory consolidation, anxiety-related behavioural tasks, and learning acquisition paradigms. The breadth of this research reflects both the compound's multi-modal mechanism — operating through BDNF, monoamine systems, and potentially direct neuropeptide receptor interactions — and its nearly four decades of active investigation in the Russian and international neuroscience literature.
Attention and Sustained Performance Research
ACTH(4-7) analogues have a well-documented history in the preclinical literature as compounds that influence sustained attention and performance on cognitively demanding tasks in rodent models. Semax, as the most metabolically stable member of this analogue class, has been used in operant conditioning paradigms requiring sustained attention — five-choice serial reaction time tasks and similar protocols — where research documents effects on response accuracy and impulsivity indices in treated versus vehicle-treated rodents. These findings are interpreted through the lens of Semax's documented monoaminergic modulation: dopamine and serotonin systems in the prefrontal cortex and striatum are primary determinants of sustained attention performance in published neuropharmacology research.
Memory Consolidation Models
The hippocampal BDNF upregulation documented by Dolotov et al. (2006) provides a mechanistic foundation for Semax's effects in memory consolidation research models. Published rodent studies using passive avoidance and Morris water maze paradigms — two standard tests of hippocampal-dependent memory consolidation — have examined Semax in both intact animals and animals with experimentally induced cognitive deficits (scopolamine-induced amnesia models, age-related cognitive decline models). In deficit models, research literature documents that Semax-treated animals show significantly faster escape latency acquisition and better retention at 24-hour probe trials relative to untreated deficit controls — findings consistent with BDNF-mediated LTP facilitation in hippocampal memory circuits.
Central Monoamine Modulation: Serotonin and Dopamine Systems
A distinct but complementary mechanism documented in published Semax research is its modulation of central monoamine neurotransmitter systems — specifically serotonin and dopamine. Eremin KO et al. (2005), published in Neurochemical Research, examined Semax's effects on monoamine metabolism in multiple rat brain regions, documenting changes in serotonin and dopamine turnover in the frontal cortex, striatum, and limbic structures following Semax administration.
The practical research significance of this monoaminergic modulation is considerable. Dopamine pathways in the prefrontal cortex and striatum govern working memory, executive function, motivational salience, and attention — the precise cognitive domains most directly implicated in the ACTH analogue literature. Serotonin system modulation in the prefrontal cortex and limbic system has documented effects on anxiety processing, emotional regulation, and the stress response — domains relevant to research examining neuropeptide effects on anxiety-related behaviour in rodent models. Semax's capacity to simultaneously modulate both systems, alongside its documented BDNF effects, positions it as a compound with multi-layered mechanisms of action in the central nervous system — a profile that distinguishes it from more pharmacologically targeted cognitive research compounds.
Researchers should note that the direction and magnitude of Semax's monoamine effects appear to be dose- and brain-region-dependent in published studies, consistent with the complex neuromodulatory role of endogenous monoamine systems in different cognitive and affective contexts.
Cognitive Neuropeptide Research Stack
Semax 10MG, Selank 10MG, and the Cognitive Focus Research Stack — all HPLC verified with batch COAs. Research use only.
View the Research Stack →Semax vs Selank: A Research Comparison
Semax and Selank are frequently examined together in the neuropeptide research literature as the two most studied compounds of the Russian synthetic neuropeptide programme. While they share structural and mechanistic characteristics — both are synthetic heptapeptides derived from endogenous neuropeptide sequences, both demonstrate DPP-IV resistance, and both show CNS activity — they emerge from different parent peptide classes and have distinct primary research profiles.
| Parameter | Semax | Selank |
|---|---|---|
| Parent peptide | ACTH(4-10) analogue | Tuftsin (Thr-Lys-Pro-Arg) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Primary research focus | Cognitive enhancement, BDNF upregulation, neuroprotection | Anxiolytic effects, stress response, GABA-A modulation |
| BDNF modulation | Documented upregulation (Dolotov et al., 2006) | Less extensively documented; some published evidence of neurotrophin modulation |
| Monoamine effects | Serotonin + dopamine modulation (Eremin et al., 2005) | Primarily serotonergic; GABA-A potentiation research |
| Ischaemia / neuroprotection data | Substantial (Gusev et al., 1997; Shadrina et al., 2010) | Limited published data in ischaemia models |
| Combined research use | Published research and researcher protocols frequently examine Semax + Selank in combination — their complementary profiles (cognitive stimulation + anxiolytic) make them a common paired research design. See the Cognitive Focus Research Stack. | |
The structural similarity between Semax and Selank — both heptapeptides with the shared C-terminal Pro-Gly-Pro stabilisation sequence — reflects a deliberate design approach by the Institute of Molecular Genetics researchers: the same metabolic stabilisation strategy applied to parent peptides with different CNS target profiles. This is why both compounds appear frequently in the same research literature and are often studied in combination protocols examining neuropeptide interactions in cognitive and stress response models.
In a 2010 gene expression study, Shadrina MI and colleagues subjected Wistar rats to a model of unilateral ischaemia and examined the transcriptional response in periinfarct cortical tissue at 24 hours. Semax-treated animals showed a markedly different gene expression profile compared to saline controls — with upregulation of neuroprotective and anti-apoptotic genes and attenuation of pro-inflammatory cytokine cascades. The researchers concluded that Semax appeared to shift the post-ischaemic transcriptional environment toward a neuroprotective phenotype rather than simply exerting a single-target pharmacological effect. The breadth of the transcriptional changes — affecting dozens of genes across multiple functional categories — was consistent with a compound operating through a neurotrophin-mediated mechanism (specifically BDNF-TrkB signalling) capable of influencing large numbers of downstream gene targets simultaneously.
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Order Semax 10MG →Frequently Asked Questions
What is Semax and what is it derived from?
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, derived from the ACTH(4-10) fragment of adrenocorticotropic hormone. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and has been approved in Russia for neurological research applications. It does not produce adrenocortical effects (cortisol stimulation) as it lacks the receptor binding domain responsible for HPA axis activity in full-length ACTH.
How does Semax upregulate BDNF?
The precise molecular mechanism by which Semax increases BDNF expression is not fully characterised in the published literature, but current evidence points to neuropeptide receptor-mediated signalling in hippocampal and cortical neurons that activates CREB (cAMP response element-binding protein) — a transcription factor upstream of the BDNF gene promoter. Dolotov et al. (2006) documented increased BDNF mRNA in hippocampal CA1 and CA3 subfields and frontal cortex following intranasal Semax administration in rats, consistent with transcriptional upregulation rather than post-translational effects.
What is the difference between Semax and Selank?
Semax is an ACTH(4-10) analogue studied primarily for BDNF upregulation, cognitive research, neuroprotection, and monoamine modulation. Selank is a Tuftsin analogue studied primarily for anxiolytic effects, stress response modulation, and GABA-A receptor interaction. Both are heptapeptides with the same C-terminal Pro-Gly-Pro stabilisation sequence, and both demonstrate DPP-IV resistance. They are frequently studied in combination in published research and researcher protocols due to their complementary neurological profiles.
Why is Semax DPP-IV resistant when native ACTH fragments are not?
Native ACTH(4-7) — the minimal active core of Semax — is rapidly cleaved by dipeptidyl peptidase IV (DPP-IV) at the N-terminal Met-Glu bond, as well as by other serum proteases, giving it a very short biological half-life. Semax's Pro-Gly-Pro C-terminal extension alters the peptide's three-dimensional conformation in a way that sterically inhibits DPP-IV's access to the cleavage site. Additionally, the extended sequence shifts the peptide's overall hydrophobicity and secondary structure, further reducing protease recognition. The result is a metabolic stability profile that makes Semax viable as a research compound where sustained CNS exposure is required.
What are the main research areas for Semax in published literature?
Published Semax research spans four primary domains: (1) BDNF upregulation and neurotrophin signalling — studied in hippocampal and cortical models; (2) neuroprotection — particularly ischaemia, oxidative stress, and post-stroke neuronal survival models; (3) cognitive research — including attention, memory consolidation, and learning acquisition paradigms in rodent behavioural models; and (4) central monoamine modulation — examining serotonin and dopamine system effects in multiple brain regions. These research areas are interconnected through shared mechanistic pathways, particularly BDNF-TrkB signalling and its downstream effects on synaptic plasticity and neuronal resilience.
Summary
Semax represents one of the most comprehensively researched synthetic neuropeptides in the published preclinical neuroscience literature. Its structural derivation from ACTH(4-10) — with the critical Pro-Gly-Pro stabilisation extension providing DPP-IV resistance — gives it metabolic properties that make it viable as a CNS research tool where native ACTH fragments are not. Its documented capacity to upregulate BDNF expression in hippocampal and cortical tissue (Dolotov et al., 2006), modulate central serotonin and dopamine systems (Eremin et al., 2005), attenuate ischaemic neuronal injury (Gusev et al., 1997), and shift post-ischaemic gene expression toward a neuroprotective phenotype (Shadrina et al., 2010) provides a mechanistically coherent picture of a multi-modal neuropeptide with broad research relevance across cognitive neuroscience, neuroprotection, and neurotrophin biology.
For researchers studying neuropeptide-mediated cognitive biology, Semax is available from Pure Grade Labs as Semax 10MG — HPLC verified, with batch-specific COA. Its research complement, Selank 10MG, is also available. Researchers combining both compounds in multi-neuropeptide protocols may find the Cognitive Focus Research Stack the most efficient procurement option. All compounds are supplied strictly for in vitro laboratory research purposes.
References
- Dolotov OV, Karpenko EA, Inozemtseva LS, et al. Semax, an analogue of ACTH(4-7) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Doklady Biochemistry and Biophysics. 2006;411(1):301–303. PMID: 17369460
- Eremin KO, Kudrin VS, Saransaari P, Oja SS, Grivennikov IA, Myasoedov NF, Rayevsky KS. Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents. Neurochemical Research. 2005;30(12):1493–1500. PMID: 16362763
- Gusev EI, Skvortsova VI, Miasoedov NF, Nezavibatko VN, Zhuravleva EIu, Vanichkin AV. Effectiveness of Semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Cerebrovascular Diseases. 1997;7(3):172. DOI: 10.1159/000107865
- Shadrina MI, Dolotov OV, Grivennikov IA, et al. Neuroprotective effect of Semax in the 6-hydroxydopamine model of Parkinson's disease. Journal of Molecular Neuroscience. 2010;41(1):52–58. PMID: 20229004
- Myasoedov NF, Grivennikov IA, Sharanaarenko NS. ACTH analogues: chemical structure, mechanisms of action, and pharmacological properties. Neuroscience and Behavioral Physiology. 1999;29(5):514–519.
- Kaplan AY, Kochetova AG, Nezavibathko VN, Rjasina TV, Ashmarin IP. Synthetic ACTH analogue Semax displays nootropic-like activity in humans. Neuroscience Research Communications. 1996;19(2):115–123.