Semax vs DSIP
Semax is the synthetic heptapeptide Met-Glu-His-Phe-Pro-Gly-Pro, the ACTH(4-7) fragment extended with a C-terminal Pro-Gly-Pro that confers resistance to enzymatic degradation. It lacks corticotropic activity and is registered in Russia for ischaemic stroke, optic nerve disease and cognitive indications. DSIP is delta sleep-inducing peptide, the nonapeptide Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu isolated in 1977 from the cerebral venous blood of rabbits in induced sleep, for which no gene, precursor protein or receptor has ever been identified. Unusually for this category, direct evidence exists. Between 2001 and 2003 one group at the Anokhin Institute of Normal Physiology in Moscow ran both peptides through the same rat models of emotional stress, treating them as parallel antistress agents. Those experiments are the whole body of head-to-head work, they were conducted in rodents, and no human study has ever compared the two compounds.
They have been compared directly.
Three rodent publications from the Anokhin Institute of Normal Physiology administered both peptides within one design, in each case comparing them as antistress agents in Wistar rats classified in advance as resistant or predisposed to emotional stress on the basis of open-field behaviour. In the 2001 study published in Stress, Sudakov and colleagues gave DSIP or the ACTH(4-10) analogue ACTH(4-7)-Pro-Gly-Pro, the sequence marketed as Semax, and counted Fos-immunoreactive cells in the parvocellular paraventricular nucleus and limbic regions using automated image analysis. Both peptides reduced stress-induced Fos expression, but their patterns differed: DSIP lowered counts in the parvocellular paraventricular nucleus and the medial and lateral septum in predisposed rats and only in the lateral septum in resistant rats, while the ACTH analogue inhibited stress-induced expression in the parvocellular paraventricular nucleus and medial septum in predisposed rats alone. Under basal conditions the two also diverged, DSIP raising Fos counts in resistant animals only and the ACTH analogue raising paraventricular counts in both groups. Koplik and colleagues then applied both peptides to serum albumin conformation in the same stress-resistance model, publishing in Russian in 2002 and in English translation in 2003. Neither of the albumin reports set out a comparative efficacy conclusion. Nothing beyond these three rodent papers has administered both compounds, and the remaining publications that engage both are reviews.
The 7 studies that tested both
- 01Animal in vivo2001
Delta-sleep inducing peptide (DSIP) and ACTH (4-10) analogue influence fos-induction in the limbic structures of the rat brain under emotional stress
Sudakov KV, et al. · Stress · Wistar rats classified as resistant or predisposed to emotional stress from open-field behaviour; intraperitoneal DSIP or the ACTH(4-10) analogue ACTH(4-7)-Pro-Gly-Pro, with automated counting of Fos-immunoreactive cells in the parvocellular paraventricular nucleus, basolateral amygdala and medial and lateral septum, under basal conditions and after restraint with intermittent shock
Both peptides reduced the paraventricular and limbic neuronal response to emotional stress, and the effect was concentrated in rats predisposed to stress. DSIP reduced Fos-immunoreactive cell counts in the parvocellular paraventricular nucleus and the medial and lateral septum in predisposed rats and in the lateral septum only in resistant rats. The ACTH(4-10) analogue inhibited stress-induced expression in the parvocellular paraventricular nucleus and medial septum in predisposed rats alone. Under basal conditions DSIP increased Fos counts in the paraventricular nucleus and lateral septum in resistant rats with no effect in predisposed rats, while the ACTH analogue increased paraventricular counts in both groups.
- 02Animal in vivo2003
Blood albumin in the mechanisms of individual resistance of rats to emotional stress
Koplik EV, et al. · Neuroscience and Behavioral Physiology · rats with different predicted levels of resistance to emotional stress; serum albumin characteristics measured under control conditions and under experimental emotional stress, with delta sleep-inducing peptide and Semax analysed as peptides that increase stress resistance
The authors examined serum albumin characteristics in rats predicted to be resistant or susceptible to emotional stress and analysed the effects of both delta sleep-inducing peptide and Semax on those characteristics in the two groups. The report is the English translation of a study first published in Russian in 2002 and did not present a comparative ranking of the two peptides.
- 03Animal in vivo2002· Russian (English abstract)
[Blood albumin in mechanisms of individual resistance of rats to emotional stress]
Koplik EV, et al. · Rossiiskii Fiziologicheskii Zhurnal Imeni I.M. Sechenova · rats with varying prognostic resistance to emotional stress, control and experimental emotional stress conditions; action of DSIP and Semax on serum albumin parameters
This is the original Russian-language report of the serum albumin work later translated into English. Both DSIP and Semax were administered as peptides that raise resistance to emotional stress, and their effects on albumin parameters were analysed in rats of differing prognostic stress resistance.
- 04Review2008· Russian (English abstract)
[Evolution of the stress concept]
Sudakov KV · Vestnik Rossiiskoi Akademii Meditsinskikh Nauk · narrative review of the stress concept and the role of neuropeptides in emotional stress
The review discussed cerebral mechanisms of emotional stress and individual tolerance to it, and identified oligopeptides including substance P, delta sleep-inducing peptide, beta-endorphin and Semax as antistress factors that increase resistance to stressful impacts. No new experimental data were presented and the two peptides were treated as members of one functional class rather than compared.
- 05Review2022
Development of Peptide Biopharmaceuticals in Russia
Deigin VI, et al. · Pharmaceutics · review of the history and current state of peptide drug development in the Russian Federation, with a catalogue of original Russian peptide preparations
Both compounds appeared in the review's catalogue of original Russian peptide preparations. Semax was listed with the sequence Met-Glu-His-Phe-Pro-Gly-Pro and classified as a nootropic drug, and the text described it as an ACTH(4-10) fragment analogue whose neuroprotective effects had been established in vitro, in animal models of cerebral ischaemia and in clinical conditions, and as used to treat ischaemic stroke. The delta sleep-inducing peptide nonapeptide was listed separately under the preparation name Deltaran and classified as a stress protector and a treatment for alcohol addiction.
- 06Review2026
Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives
Renke G, Chinellato L · International Journal of Molecular Sciences · narrative review of therapeutic peptides in aesthetic, metabolic and endocrine practice, including a section on neuromodulator peptides
The review grouped Semax, Selank and delta sleep-inducing peptide together as neuromodulator peptides used for cognition, mood and sleep. Semax was described as a synthetic ACTH fragment given as nasal drops that potentiates neurotrophic factor signalling and lacks classic stimulant effects, while delta sleep-inducing peptide was described as given by intramuscular injection with a half-life of minutes and rapid elimination. The review addressed formulation, safety and quality-control concerns for the class rather than generating comparative efficacy data.
- 07Review2026
Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions
Rahman OF, et al. · JAAOS Global Research & Reviews · narrative review of therapeutic peptide classes proposed as adjuncts in orthopaedic injury management
The review assigned the two peptides to different categories. Delta sleep-inducing peptide appeared in a table of sleep and recovery agents, described as named for promoting slow-wave sleep in rodent studies and as possibly increasing endogenous growth hormone secretion, while Semax appeared among neuroactive peptides said to enhance brain-derived neurotrophic factor signalling. No comparison was made between them, and the authors concluded that clinical trials for the class are currently lacking.
Side by side.
| Semax | DSIP | |
|---|---|---|
| Evidence maturity | Approved drug | Preclinical only |
| Studies cited here | 18 | 17 |
| Published 2023 or later | 10 | 1 |
| Newest paper | 2025 | 2024 |
| Sequence and origin | A synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro, corresponding to the ACTH(4-7) fragment with a Pro-Gly-Pro extension that blocks rapid degradation. It was designed at the Institute of Molecular Genetics in Moscow and has no corticotropic activity. | A nonapeptide, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, isolated from rabbit cerebral venous blood in 1977 rather than designed. No gene, precursor protein or receptor has since been identified for it. |
| Mechanism as described in the literature | Regulation of BDNF and NGF expression and broad transcriptomic modulation of inflammatory and neurosignalling genes in rodent cerebral ischaemia, with additional in vitro work on copper chelation from amyloid beta and on intracellular calcium dynamics in brain slices. | No identified receptor. Reported actions include blood-brain barrier transport, modulation of stress and hypothalamic-pituitary-adrenal responses, antioxidant enzyme gene expression in ageing rodents, and a rat link between the peptide, slow-wave sleep and sleep-associated growth hormone release. |
| Size of the evidence base | Eighteen verified publications in the research entry here: eight rodent in vivo studies, six human clinical studies and four in vitro studies. | Seventeen verified publications: eight rodent in vivo studies, seven human studies and two reviews, thinly spread from 1983 to 2024. |
| Best-characterised finding | Region-dependent normalisation of ischaemia-disrupted gene expression in rat transient middle cerebral artery occlusion, replicated across several RNA sequencing studies from the same group between 2023 and 2025, alongside the older neurotrophin-induction work. | A 1988 rat report linking DSIP to slow-wave sleep and sleep-associated growth hormone release, which remains the most frequently cited mechanistic basis for the compound's sleep claims. |
| Human data | Six studies, dominated by Russian work in ischaemic stroke, optic nerve disease and motor neuron disease, plus two small placebo-controlled resting-state fMRI studies in healthy volunteers. The stroke and ophthalmology trials were open-label or actively controlled rather than double-blind and placebo-controlled. | Seven studies, most conducted before 1999 by intravenous administration, including a double-blind polysomnographic study in chronic insomnia that reported only weak effects and a randomised anaesthesia study in which the peptide reduced delta rhythm and raised the bispectral index. |
| Evidence maturity | Approved drug, but only in Russia. No Semax trial has been registered or completed to EMA or FDA standards, and the marketing authorisation rests on domestic trials that were largely open-label or actively controlled. | Preclinical only. Human work exists but predates modern trial standards and has not been reproduced under contemporary methodology; no modern randomised controlled trial has been conducted. |
| Recency of primary research | Active. Ten publications in the entry are dated 2023 or later, including 2025 work on an Alzheimer model, spinal cord injury in mice, calcium dynamics in brain slices and copper-amyloid chemistry. | Nearly dormant. One publication in the entry is dated 2023 or later, a 2024 report on a recombinant fusion peptide expressed in Pichia pastoris and tested in a chemically induced insomnia mouse model. |
| Safety signals reported | An open-label trial in motor neuron disease reported no influence on the course of chronic partial denervation, and a 2018 stroke rehabilitation trial reported tolerability without attributed adverse events. No long-term or dose-ranging safety data exist in Western populations. | A randomised study during isoflurane anaesthesia reported increased heart rate, decreased heart rate variability and a lightening rather than deepening of anaesthetic depth. Early human reports described good tolerability provided injection was slow. No controlled safety dataset exists. |
And what it does not.
Direct evidence exists here, which is rare for this category, but it is narrow. One Moscow group ran both peptides through the same rat emotional-stress models between 2001 and 2003, treating them as parallel antistress agents. The Fos-mapping study found that both blunted the paraventricular and limbic response to stress and that their regional patterns differed, with effects concentrated in animals predisposed to stress; the albumin studies applied both peptides without setting out a comparative ranking. Those are rodent experiments about stress reactivity, not about sleep, cognition or stroke recovery, and none of them was designed to establish which compound is more useful for anything. Away from that work the two records are asymmetric. Semax is a registered drug in one country with an active and growing preclinical literature and human trials that were mostly open-label or actively controlled. DSIP has an older, smaller human record with inconsistent results and a contested claim to being an endogenous sleep factor at all. Neither has evidence meeting Western regulatory standards.
Common questions.
- What did the study that gave rats both peptides actually measure?
It measured immediate-early gene activation. Wistar rats were classified in advance as resistant or predisposed to emotional stress from open-field behaviour, then given DSIP or the ACTH(4-10) analogue that corresponds to Semax, and Fos-immunoreactive cells were counted automatically in the parvocellular paraventricular nucleus, basolateral amygdala and medial and lateral septum. The endpoint was neuronal activation under basal conditions and after restraint with intermittent shock, not sleep quality, cognition or any behavioural outcome that would map onto how either compound is marketed.
- Did the direct comparison show one peptide to be stronger than the other?
No ranking was reported. Both peptides reduced stress-induced Fos expression, and the difference between them was regional rather than a matter of magnitude: DSIP acted across the parvocellular paraventricular nucleus and both septal regions in predisposed rats, while the ACTH analogue acted on the paraventricular nucleus and medial septum in predisposed animals only. The two also behaved differently under basal conditions. The authors framed both as antistress peptides with distinguishable brain-activation profiles rather than as competitors.
- Why is Semax an approved drug while DSIP is not?
Semax holds a Russian marketing authorisation for ischaemic stroke, optic nerve disease and cognitive indications, granted on the basis of domestic trials that were largely open-label or actively controlled rather than double-blind and placebo-controlled. No Semax trial has been registered or completed under EMA or FDA standards. DSIP never reached registration anywhere; its human work stopped in the 1990s with inconsistent sleep outcomes, and the underlying hypothesis that it is an endogenous sleep factor remains disputed in the primary literature.
- Are the two compounds still being researched at the same rate?
They are not. Ten of the eighteen publications in the Semax entry are dated 2023 or later, including 2025 studies in an Alzheimer model, in mouse spinal cord injury, in brain-slice calcium imaging and in copper-amyloid chemistry, and several are non-Russian. Only one of the seventeen DSIP publications is dated 2023 or later. The DSIP literature is now largely historical, with recent activity confined to rodent stroke and hypoxia models and to drug-delivery constructs rather than to sleep itself.
- Has anything compared the two peptides in humans?
Nothing has. The three publications that administered both were rat experiments from one Moscow institute. The remaining papers naming both compounds are reviews: a 2008 Russian review of the stress concept that listed them together as antistress oligopeptides, a 2022 review of Russian peptide drug development that catalogued Semax as a nootropic and the DSIP nonapeptide as a stress protector, and two 2026 narrative reviews that placed them in adjacent categories without comparing them.
For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice, and no comparison here should be read as a recommendation of either compound.