COGNITIVE & NOOTROPIC RESEARCH / MATRIX
Three Peptides, One Shared Route
How a neuroprotective fragment, an anxiolytic heptapeptide, and an unresolved sleep peptide differ in mechanism and evidence — and why intranasal delivery keeps showing up in all three literatures.
The short version
This page lines up Semax, Selank, and DSIP on the dimensions that matter most when reading intranasal neuropeptide research: mechanism, most-studied application, the intranasal-dosing evidence specifically, overall evidence base, regulatory standing, and the single most important caution for each. The pattern is simple to state and worth being precise about: all three have been studied, in part, by the intranasal route, and all three remain unapproved research chemicals in the United States — but they differ sharply in how well their mechanisms and long-term safety are actually characterized. Nothing on this page is medical advice, and no human dose is recommended.
The comparison matrix
| Dimension | Semax | Selank | DSIP |
|---|---|---|---|
| Peptide class | Stabilized ACTH(4-7) fragment | Tuftsin-derived heptapeptide | Endogenous nonapeptide, no identified receptor |
| Most studied for | Neuroprotection, cognition, mood | Anxiolysis (anxiety reduction) | Delta-wave sleep promotion |
| Intranasal dosing evidence | 50-250 microg/kg in rats, region-specific neurotrophin and BDNF changes [3][4] | Intranasal dosing shown to raise hippocampal BDNF in rats [9] | Intranasal DSIP improved post-stroke motor recovery in rats [17] |
| Evidence base | Rodent cerebral-ischemia and spinal-cord-injury models; Russian clinical practice [1][2][5] | Small Russian clinical studies plus rodent GABAergic work [6][7][10] | Small 1980s human pilot trials; mechanism still unresolved [12][14][15] |
| Regulatory status | Prescription drug in Russia/Ukraine; unapproved research chemical in the US | Registered anxiolytic in Russia; unapproved research chemical in the US | Not approved anywhere; unapproved research chemical in the US |
| Key caution | Powerful, incompletely understood neurotrophin and gene-expression effects [1][2][3] | Interaction unknowns across GABAergic, opioid, and immune signaling [7][10] | No identified receptor after 40+ years; a large share of users report no effect [12] |
Why intranasal delivery shows up in all three
None of these three compounds were designed together, and their mechanisms have almost nothing in common. What they share is that researchers, working independently, each chose to test intranasal administration at some point: a 50 microg/kg intranasal dose of Semax shifted neurotrophin gene expression across several rat brain regions within hours [3]; intranasal Selank raised hippocampal BDNF expression in rats [9]; and intranasal DSIP improved motor-function recovery after stroke in rats without significantly shrinking the infarct [17]. The nasal route is attractive to researchers precisely because it may reach brain tissue via pathways that bypass some of the barriers a swallowed or injected compound faces — but "studied intranasally in an animal model" is a research finding, not a human-use instruction, and this page does not convert any of the doses above into a recommendation.
Mechanism
Semax's mechanism centers on neurotrophin upregulation (BDNF, NGF) through a specific, reversible, calcium-dependent binding site (KD ~2.4 nM), with a secondary contribution from inhibiting enzymes that degrade endogenous opioid-like peptides [4]. Selank's mechanism runs through positive allosteric modulation of GABA receptors and the same enkephalinase-inhibition pathway, plus a tuftsin-inherited immunomodulatory effect on Th1/Th2 cytokine balance [6][10]. DSIP's mechanism is, by comparison, essentially unresolved: no receptor, gene, or precursor has been isolated, and its proposed roles rest on a blood-brain-barrier transporter, a dopaminergic relay for its growth-hormone effect, and a speculative endogenous-opioid interaction [12].
Most-studied application
Semax's literature centers on cerebral ischemia, spinal-cord injury, and cognitive/neurotrophic effects, largely from Russian research groups [1][2][5]. Selank's centers on anxiolysis — reducing anxiety-like behavior in stress models and, in a small human study, anxiety-asthenic disorders — with a GABAergic and immunomodulatory frame [6][7][10]. DSIP's centers on sleep, tested since the 1980s in small human insomnia trials, alongside more recent rodent work on stroke recovery and a striking but single-lineage lifespan and tumor-incidence study in mice [13][15][17].
Evidence base
All three share a structural weakness: the great majority of the literature for each comes from a small number of research groups, heavily weighted toward Russia and Ukraine, with limited independent Western replication. Semax and Selank have the more developed evidence bases of the three, spanning multiple rodent-injury models plus some human clinical experience under Russian registration [1][2][6][7][10]. DSIP's evidence is thinner and older on the human side — small 1980s pilot studies — even though a 2024 engineered-fusion-peptide study and a 2021 stroke-recovery study show continuing research interest [11][14][15][17]. None of the three has been through a large, modern, Western randomized controlled trial.
Regulatory and safety status
Semax and Selank are registered prescription pharmaceuticals in Russia — Semax for stroke, cognitive impairment, and optic-nerve disease; Selank as an anxiolytic — but neither is approved by the FDA or EMA. DSIP has never been approved by any regulator anywhere, despite carrying the assigned INN Emideltide. In the United States, all three are sold only as unscheduled research chemicals, meaning no regulator verifies the identity, purity, or sterility of what a given supplier ships.
Key caution
Each compound carries a defining caveat. For Semax, it is that the peptide produces powerful, incompletely understood changes in neurotrophin and immune-gene expression [1][2][3] — biology that may help in an injury model but is not automatically safe as an ongoing habit. For Selank, it is the number of physiological systems it touches at once — GABAergic, endogenous-opioid, monoaminergic, and immune signaling [7][10] — each an unstudied axis for interaction with common medications. For DSIP, it is more fundamental: no receptor has been identified after more than forty years of research [12], and a large share of people who try it report no effect at all — a pattern that shows up consistently in both the formal literature and community reports.