The Ultimate Nootropic Stack: Semax, Selank, Dihexa, VIP & DSIP

Cognitive optimization through peptides involves more than simply boosting a single neurotransmitter. This stack combines five peptides that operate through distinct and complementary neurotrophic mechanisms: Semax for BDNF-driven neuroplasticity, Selank for GABAergic anxiolysis, Dihexa for HGF/c-Met-mediated synaptogenesis, VIP for neuroprotection and cerebral blood flow, and DSIP for sleep architecture optimization that consolidates daytime cognitive gains.

Stack Overview

Individual Peptide Roles

Semax: The Neuroplasticity Activator

Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic analog of ACTH(4-10) developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It is approved in Russia and several CIS countries for the treatment of stroke, cognitive disorders, and optic nerve atrophy.

• BDNF upregulation — Semax significantly increases brain-derived neurotrophic factor expression in the hippocampus and cortex. BDNF is the primary driver of long-term potentiation (LTP), the molecular basis of learning and memory Dolotov et al., 2006
• NGF expression — Upregulates nerve growth factor, supporting cholinergic neuron survival and function Agapova et al., 2008
• Dopamine and serotonin modulation — Enhances dopaminergic and serotonergic signaling in the striatum and cortex, contributing to focus, motivation, and mood Eremin et al., 2005
• Neuroprotection in stroke — Clinically used in Russia for acute ischemic stroke. Reduces infarct size and improves neurological outcomes when administered within 6 hours of onset Gusev et al., 1997
• Cognitive enhancement — Improves attention, memory consolidation, and information processing speed in both impaired and healthy subjects

Selank: The Anxiolytic Stabilizer

Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a synthetic analog of the immunomodulatory peptide tuftsin, also developed at the Institute of Molecular Genetics. It is approved in Russia as an anxiolytic and nootropic.

• GABA modulation — Selank enhances GABAergic transmission by increasing GABA receptor expression and sensitivity, producing anxiolytic effects comparable to benzodiazepines but without sedation, tolerance, or dependence Seredenin et al., 1998
• Enkephalin stabilization — Inhibits enkephalinase, the enzyme that degrades endogenous enkephalins. This extends the half-life of the body's natural opioid peptides, contributing to stress resilience and mood stability Zozulya et al., 2001
• IL-6 modulation — Modulates inflammatory cytokine expression in the brain, reducing neuroinflammation that impairs cognitive function Uchakina et al., 2008
• Gene expression — Influences the expression of 36 genes involved in GABAergic signaling, serotonin transport, and immune regulation within 1 hour of administration
• No sedation — Unlike benzodiazepines and most GABA-enhancing compounds, Selank does not cause drowsiness, cognitive impairment, or motor coordination deficits

Semax + Selank Synergy

The Semax-Selank combination is one of the most widely used nootropic pairings in Russian clinical practice. The rationale is complementary:

Semax drives cognitive "acceleration" — more BDNF, more neuroplasticity, more dopamine-driven focus and motivation. However, heightened neural activity can increase anxiety in susceptible individuals.

Selank provides cognitive "stabilization" — GABAergic calming, stress resilience, emotional equanimity. It prevents the anxiety edge that can accompany dopaminergic activation without blunting the cognitive benefits.

Together, they produce focused clarity without jitteriness — the "calm alertness" often described by researchers and clinicians.

Dihexa: The Synaptogenesis Catalyst

Dihexa (N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide) is a modified angiotensin IV analog developed at Washington State University by Dr. Joseph Harding's laboratory. It is approximately 10 million times more potent than BDNF at promoting synaptogenesis in vitro.

• HGF/c-Met activation — Dihexa binds hepatocyte growth factor (HGF) and potentiates its interaction with the c-Met receptor. This pathway drives dendritic spine formation, synaptic plasticity, and neuronal survival McCoy et al., 2013
• Synaptogenesis — Promotes the formation of new synaptic connections between neurons, directly increasing the brain's capacity for information processing and memory storage
• Memory restoration — In aged rats with scopolamine-induced cognitive impairment, Dihexa completely restored spatial learning and memory performance to levels comparable to young animals Benoist et al., 2011
• Blood-brain barrier penetration — Dihexa is orally active and crosses the blood-brain barrier effectively, making it one of the few oral peptide-derived nootropics
• Novel mechanism — The HGF/c-Met pathway is distinct from the BDNF/TrkB and NGF/TrkA pathways targeted by Semax, meaning Dihexa and Semax stimulate synaptogenesis through independent and potentially synergistic routes

VIP: The Neuroprotective Vasodilator

VIP (Vasoactive Intestinal Peptide) is a 28-amino acid neuropeptide with broad functions in the nervous, immune, and circulatory systems. In the context of cognitive optimization, its primary roles are cerebral blood flow enhancement and neuroprotection.

• Cerebral vasodilation — VIP is one of the most potent vasodilators of cerebral blood vessels, increasing blood flow to the brain and enhancing oxygen and nutrient delivery Henning & Bhatt, 1986
• Anti-inflammatory neuroprotection — Inhibits microglial activation and reduces production of pro-inflammatory cytokines (TNF-alpha, IL-1beta, IL-6) in the CNS. Neuroinflammation is increasingly recognized as a driver of cognitive decline Delgado et al., 2003
• Circadian regulation — VIP is a key signaling molecule in the suprachiasmatic nucleus (SCN), the brain's master circadian clock. It synchronizes neuronal firing rhythms essential for sleep-wake cycles and cognitive performance Aton et al., 2005
• Neuronal survival — Protects neurons against glutamate excitotoxicity, oxidative stress, and beta-amyloid toxicity Gozes & Brenneman, 2000
• CIRS/mold illness — VIP is used clinically by practitioners treating Chronic Inflammatory Response Syndrome (CIRS), where cognitive dysfunction ("brain fog") is a primary symptom

DSIP: The Sleep Architect

DSIP (Delta Sleep-Inducing Peptide) is a naturally occurring 9-amino acid neuropeptide first isolated from rabbit brain in 1977. Despite its name, DSIP's mechanism is more nuanced than simply inducing sleep.

• Delta wave enhancement — DSIP promotes slow-wave (delta) sleep, the deepest phase of non-REM sleep. Delta sleep is critical for memory consolidation, synaptic pruning, and glymphatic clearance of metabolic waste (including beta-amyloid) Schneider-Helmert & Schoenenberger, 1983
• Cortisol modulation — Normalizes the cortisol rhythm, reducing elevated cortisol that impairs hippocampal function and memory. Particularly relevant for individuals with disrupted HPA axis function due to chronic stress Graf & Kastin, 1984
• Stress resilience — Enhances the body's adaptive response to physical and psychological stress, improving cognitive performance under pressure
• LH modulation — Modulates luteinizing hormone release, with potential downstream effects on hormonal balance
• Sleep quality vs quantity — DSIP improves sleep architecture (proportion of restorative delta sleep) rather than simply increasing total sleep time, making it distinct from sedatives

Mechanism of Synergy

The five peptides address cognitive optimization from complementary angles:

Research Protocol

Dosing Table

Administration Notes

• Semax intranasal — Use a calibrated nasal spray delivering ~100 mcg per spray. Administer 1-3 sprays per nostril. Allow 30 seconds between nostrils. Avoid blowing nose for 10 minutes after administration. The N-Acetyl-Semax-Amidate (NASA) form has enhanced stability and potency
• Selank intranasal — Same nasal spray technique as Semax. Can be administered simultaneously with Semax (one in each nostril) or sequentially. The N-Acetyl-Selank-Amidate form is preferred for enhanced stability
• Dihexa — Oral dosing is the most common route due to confirmed blood-brain barrier penetration and oral bioavailability. Subcutaneous dosing uses significantly lower amounts due to bypassing first-pass metabolism
• VIP intranasal — Use a calibrated nasal spray. Start at the lower end (50 mcg) and titrate up. VIP can cause vasodilation-related flushing and mild hypotension in sensitive individuals
• DSIP — Subcutaneous injection in the evening. Effects typically begin within 20-30 minutes. DSIP does not cause acute sedation but promotes natural sleep onset and improves sleep architecture

Sample Daily Schedule

Cycling Recommendations

• Semax and Selank are typically cycled together on the same schedule for simplicity
• Dihexa is the most novel compound in this stack with the least clinical data. Conservative cycling with adequate breaks is recommended
• VIP and DSIP are endogenous neuropeptides with lower tolerance concerns. Continuous use is reasonable but periodic breaks allow assessment of baseline function

Monitoring & Assessment

Cognitive Tracking

Blood Work

Safety Considerations

• Semax — Extensive Russian clinical data supports a strong safety profile. Most common side effect is mild nasal irritation from intranasal delivery. Avoid in individuals with seizure disorders, as BDNF upregulation could theoretically lower seizure threshold. Not recommended during active manic episodes in bipolar disorder
• Selank — Well-tolerated with minimal reported side effects. Unlike benzodiazepines, no sedation, dependence, or withdrawal. May theoretically over-enhance GABA signaling in individuals already taking GABAergic medications (benzodiazepines, gabapentin, pregabalin)
• Dihexa — The least clinically characterized peptide in this stack. HGF/c-Met activation is involved in cell proliferation and is dysregulated in certain cancers. Contraindicated in individuals with active malignancies or history of HGF/c-Met-driven cancers McCoy et al., 2013. Long-term safety data in humans is not available
• VIP — Can cause transient flushing, nasal congestion, and mild hypotension due to vasodilatory effects. Start with low doses and titrate. Contraindicated with severe hypotension. May interact with antihypertensive medications
• DSIP — Generally well-tolerated. Does not cause morning grogginess or rebound insomnia. Limited long-term human safety data. Avoid combining with sedative medications

Important: Dihexa's potent activation of the HGF/c-Met pathway warrants caution. While this mechanism drives beneficial synaptogenesis, c-Met is a proto-oncogene. Individuals with personal or family history of c-Met-associated cancers should avoid Dihexa.

References

1. Dolotov et al., 2006 — Semax, an analog of ACTH(4-10), increases BDNF expression in the rat hippocampus
2. Agapova et al., 2008 — Effect of Semax on the expression of BDNF and NGF genes
3. Eremin et al., 2005 — Semax effect on dopamine and serotonin metabolism in rat brain
4. Gusev et al., 1997 — Neuroprotective effects of Semax in acute period of ischemic stroke
5. Seredenin et al., 1998 — Selank and its anxiolytic activity
6. Zozulya et al., 2001 — Selank and its influence on enkephalin degradation
7. Uchakina et al., 2008 — Immunomodulatory activity of Selank
8. McCoy et al., 2013 — Dihexa, a HGF/c-Met agonist, enhances memory consolidation
9. Benoist et al., 2011 — Cognitive-enhancing properties of angiotensin IV analogs
10. Henning & Bhatt, 1986 — Vasoactive intestinal peptide and cerebral blood flow
11. Delgado et al., 2003 — VIP prevents experimental arthritis by downregulating inflammatory and autoimmune responses
12. Aton et al., 2005 — VIP coordinates circadian rhythms in the suprachiasmatic nucleus
13. Gozes & Brenneman, 2000 — VIP: a neuroprotective drug
14. Schneider-Helmert & Schoenenberger, 1983 — Effects of DSIP in man: sleep laboratory studies
15. Graf & Kastin, 1984 — Delta sleep-inducing peptide: a review of its structure, action, and physiology