COGNITIVE & NOOTROPIC RESEARCH / FAQ
Questions From the Research Record
Direct, citation-anchored answers to the questions readers most often bring to semax, selank and DSIP.
What is Semax?
Semax is a synthetic linear heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) built from a small fragment of the natural hormone ACTH, extended with a stabilizing Pro-Gly-Pro tail. It is studied for its rapid, region-specific effect on the neurotrophins BDNF and NGF, and for neuroprotection in animal models of stroke and spinal-cord injury [3][4][1]. It is a registered prescription drug in Russia and Ukraine, but is not approved by the FDA for any indication in the United States, where it is sold, when it is sold, only as a research chemical.
What is Semax peptide used for?
In the research literature, semax has been studied for functional recovery after spinal-cord injury [1], neuroprotection and reduced infarct volume in cerebral-ischemia models [2][5], and its effect on cognitive/memory-task performance via its neurotrophin action [3][4]. In Russian clinical practice it is registered for ischemic stroke, transient ischemic attack, cognitive impairment and optic-nerve disease. Outside that clinical context, it is sold only as a research chemical, and this page does not recommend it for any human use.
Is Semax a peptide?
Yes. Semax is a synthetic linear heptapeptide — a chain of seven amino acids (Met-Glu-His-Phe-Pro-Gly-Pro) — built from a fragment of the natural hormone adrenocorticotropic hormone (ACTH) with an added stabilizing tail. Full detail on its structure and synonyms is on the semax page.
How does Semax work?
Semax's best-characterized mechanism is a rapid, region-specific increase in the neurotrophins BDNF and NGF in rodent brain tissue, documented both at the gene-expression level [3] and the protein level, where it also binds a specific, reversible, calcium-dependent site (KD ≈ 2.4 nM) [4]. It separately inhibits enzymes that break down the body's own endogenous opioid peptides [7]. In brain-injury models, its protective effect is thought to come more from a broad shift toward immune modulation and improved vascular gene expression than from any single receptor [2].
What is Selank?
Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) built from tuftsin, a naturally occurring immune-signaling fragment of the antibody IgG, extended with the same stabilizing Pro-Gly-Pro tail used in semax. It is studied primarily as a non-benzodiazepine anxiolytic, with anxiolytic activity attributed to positive allosteric modulation of GABA receptors [8]. It is registered as an anxiolytic prescription drug in Russia only; it is not FDA-approved.
What does Selank do?
In animal and limited human research, selank has been studied for reducing anxiety-like behavior, including in combination with the benzodiazepine diazepam, where the combination outperformed either agent alone in a chronic-stress rat model [9]. It also increases BDNF expression in rat hippocampus [11] and, in a study of human patients with anxiety-asthenic disorders, shifted the Th1/Th2 cytokine balance, supporting a documented immunomodulatory effect alongside its anxiolytic action [12].
What is Selank peptide used for?
Selank's studied applications are anxiety reduction (anxiolysis) and, secondarily, cognitive and mood-related effects proposed to follow from its GABAergic and BDNF actions. Its only formal clinical registration is as an anxiolytic in Russia, based on studies in patients with anxiety-asthenic disorders [12]. Outside that regulatory context it is sold, where available, only as a research chemical, and this page makes no recommendation for human use.
How does Selank work?
Selank's anxiolytic mechanism centers on positive allosteric modulation of GABA receptors — the brain's main inhibitory signaling system — through a route distinct from benzodiazepines, though it can interact with diazepam's binding site [8]. It also inhibits enkephalin-degrading enzymes, prolonging endogenous opioid signaling, alters serotonin and dopamine turnover, raises hippocampal BDNF [11], and modulates immune cytokine balance [12] — a wider mechanistic footprint than a typical anxiolytic.
What is DSIP peptide?
DSIP (delta sleep-inducing peptide) is a small naturally occurring nonapeptide (sequence WAGGDASGE), first isolated in the 1970s from the cerebral venous blood of rabbits during electrically induced sleep. Unlike semax and selank, it is not an engineered analog of a larger hormone fragment. Despite more than forty years of research, no specific DSIP receptor, gene or precursor protein has ever been conclusively identified [14]. It is not approved as a drug by any regulator.
What is DSIP peptide used for?
DSIP has been studied primarily for delta-wave sleep promotion and modulation of the HPA (stress-hormone) axis. Human evidence includes a small 1980s study finding improved sleep duration, fewer interruptions and slightly more REM sleep after intravenous administration in chronic insomniacs [17], and a separate study finding a temporary reduction in a marker of ACTH activity after intravenous dosing in men, with cortisol unaffected [16]. A 2024 rodent study of an engineered DSIP fusion peptide showed improved recovery in an induced-insomnia model [13].
What are the benefits of DSIP peptide?
In the cited literature, the clearest documented effects are modest improvements in sleep quality in a small human pilot study [17], a temporary HPA-axis effect in men [16], and — in a 2024 rodent study of an engineered fusion form — reduced wakefulness, restored neurotransmitter levels, anxiolytic- and antidepressant-like behavioral effects, and increased hippocampal neuron density in an insomnia model [13]. DSIP's own most-cited review is explicit that the underlying sleep-promotion hypothesis for the native peptide is "extremely poorly documented and still weak" [14], so these findings should be read as preliminary rather than established.
Does DSIP really work?
The honest answer from the literature is: inconsistently, and the mechanism explaining why is unknown. A 2006 review — the field's most-cited critical appraisal — found no confirmed DSIP receptor after decades of study and described the sleep-promotion evidence for native DSIP as weak, noting that engineered analogs showed clearer effects than the native peptide [14]. Community reports echo this: a large share of people who try DSIP report no noticeable effect, a pattern consistent with the compound's non-monotonic (parabolic) dose-response and unresolved mechanism. The 2024 engineered fusion-peptide study is the newest and most methodologically rigorous positive result, but it concerns an analog, not native DSIP [13].