BDNF Upregulation & Neuroprotective Signaling
Semax — ACTH(4-7) Pro-Gly-Pro Analog Nootropic
Semax is a synthetic heptapeptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, based on the ACTH(4-7) fragment (Met-Glu-His-Phe) with a C-terminal Pro-Gly-Pro extension for metabolic stability. It is approved in Russia and Ukraine as a nootropic and neuroprotective agent, with clinical applications in stroke rehabilitation, cognitive impairment, and attention deficit disorders.
Semax is distinguished from most nootropic compounds by its robust, well-characterized effect on brain-derived neurotrophic factor (BDNF) and its receptor TrkB — a neurotrophin signaling pathway that is central to synaptic plasticity, neurogenesis, and neuroprotection. Its mechanism is fundamentally different from stimulant-based cognitive enhancers, operating through neurotrophic rather than catecholaminergic pathways.
Semax has the amino acid sequence Met-Glu-His-Phe-Pro-Gly-Pro, with a molecular weight of 813.94 Daltons. The core ACTH(4-7) sequence (Met-Glu-His-Phe) is the minimal fragment of adrenocorticotropic hormone that retains cognitive-enhancing activity without the adrenocortical stimulation of the full ACTH molecule. The Pro-Gly-Pro extension dramatically extends metabolic stability compared to the parent ACTH(4-7) tetrapeptide.
Semax's primary mechanism involves upregulation of BDNF and its high-affinity receptor TrkB in the hippocampus, frontal cortex, and basal forebrain. BDNF/TrkB signaling activates the PI3K/Akt and MAPK/ERK pathways, promoting neuronal survival, synaptic plasticity (LTP), and neurogenesis in the hippocampal dentate gyrus — the cellular substrates of learning and memory.
Semax also modulates the dopaminergic and serotonergic systems, increasing catecholamine turnover in the prefrontal cortex and limbic system. Additionally, it has been shown to reduce neuroinflammation by suppressing NF-κB-mediated cytokine expression (IL-1β, TNF-α) in activated microglia, providing neuroprotective effects in ischemic and inflammatory models.
In rodent models of stroke, semax administration significantly reduces infarct volume and improves functional recovery, effects attributed to both its BDNF-mediated neuroprotection and its anti-inflammatory activity.
Semax is a synthetic heptapeptide derived from a fragment of ACTH (adrenocorticotropic hormone) — a pituitary hormone — with modifications to remove its hormonal activity while preserving its neurological effects. Like Selank, it was developed in Russia and is approved there as a nootropic and neuroprotective drug. It's one of the most widely used cognitive peptides in the Russian medical system.
Semax's primary mechanism is the upregulation of BDNF (Brain-Derived Neurotrophic Factor) and NGF (Nerve Growth Factor) — proteins that promote the survival, growth, and maintenance of neurons. It also modulates dopaminergic and serotonergic neurotransmission, which may explain its reported effects on focus, memory, and mood. In Russian clinical use, it's been studied for stroke recovery, ADHD, optic nerve disease, and cognitive decline.
BDNF is one of the most important molecules in brain health — it's been called 'Miracle-Gro for the brain.' Low BDNF is associated with depression, cognitive decline, and neurodegenerative disease. A compound that reliably upregulates BDNF is of significant interest to neuroscience researchers. Semax's clinical use in Russia for stroke recovery provides a neuroprotection angle that's particularly compelling.
Semax is a well-characterized nootropic peptide with approved clinical status in Russia for neurological conditions. Its BDNF-upregulating mechanism is grounded in solid neuroscience. Like Selank, its evidence base is primarily in the Russian literature, though the underlying biology (BDNF, NGF) is extensively validated in Western research. Research-only compound outside Russia.
Upregulates BDNF and TrkB in hippocampus and frontal cortex, activating PI3K/Akt and MAPK/ERK pathways for neuroplasticity and neuroprotection.
BDNF/TrkB-mediated enhancement of long-term potentiation in hippocampal circuits, the cellular basis of learning and memory consolidation.
Reduces microglial NF-κB activation and pro-inflammatory cytokine expression (IL-1β, TNF-α), providing neuroprotective effects.
Modulates dopaminergic and serotonergic turnover in prefrontal cortex and limbic system, contributing to cognitive and mood effects.
2 cited studies — model, sample size, outcome, and effect size from published literature.
| Study | Model | Sample | Outcome | Effect Size | Level |
|---|---|---|---|---|---|
Dolotov OV, et al. (2006) Semax, an analog of ACTH(4-7) with cognitive effects, regulates BDNF and trkB ex… PubMed | Rodent (rat) — hippocampus | n=24 | Significant upregulation of BDNF and TrkB expression in hippocampus | BDNF mRNA: ~2× increase vs. control; TrkB: ~1.5× increase | Animal |
Gusev EI, et al. (1997) Neuroprotective effects of Semax in patients with ischemic stroke PubMed | Human — clinical trial (ischemic stroke) | n=187 | Improved neurological outcomes and reduced disability in acute ischemic stroke | Significant improvement in neurological deficit scores vs. control (p<0.05) | Observational |
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| Peptide Class | Synthetic heptapeptide (ACTH(4-7) analog) |
| Molecular Weight | 813.94 Da |
| Regulatory Status | Approved nootropic/neuroprotective in Russia and Ukraine |
| Parent Sequence | ACTH(4-7) + Pro-Gly-Pro stability extension |
| Available Sizes | 5mg vials |
| Form | Lyophilized powder |
| Purity | ≥99% (third-party tested) |
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Purchase Semax at Purgo LabsMedical Disclaimer: All content on this site is for educational and research purposes only. Research peptides are not FDA-approved for human use. Always consult a qualified healthcare professional before considering any peptide or supplement protocol. Nothing on this site constitutes medical advice, diagnosis, or treatment.
