What are the proposed GABAergic mechanisms of DSIP?

DSIP is proposed to modulate GABAergic tone in the brainstem reticular activating system and hypothalamus, potentially through interaction with GABA-B receptors or by enhancing endogenous GABAergic inhibition of arousal circuits. However, a dedicated DSIP receptor has not been definitively characterised.

How does DSIP affect the HPA axis in research models?

DSIP has been shown to suppress CRH-stimulated ACTH secretion from anterior pituitary cells in vitro and to reduce stress-induced corticosterone elevations in rodent models, suggesting an inhibitory role in HPA axis reactivity independent of its sleep-regulatory actions.

// Neuropeptides / Sleep Research

DSIP (Delta Sleep-Inducing Peptide)

Name: DSIP (Delta Sleep-Inducing Peptide)
Brand: BasedPeps

CAS No. 62568-57-4

Molecular Weight 849.9 g/mol

Research Category Neuropeptides / Sleep Research

Sizes Available 5 mg · Spray 10 mL

Delta sleep-inducing peptide (DSIP) is a nonapeptide (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) first isolated by Monnier and colleagues (1977) from rabbit cerebral venous blood during electrically-evoked slow-wave sleep. When infused into recipient rabbits, it promoted slow-wave sleep architecture characterised by increased delta EEG power — coining its designation. Beyond sleep regulation, DSIP is studied for HPA axis modulation, stress-resilience neurobiology, and putative GABAergic circuit interactions in preclinical research models.

// 01 — Mechanism

Mechanism of Action

DSIP's molecular receptor has not been definitively identified — no high-affinity, selective DSIP receptor has been cloned and characterised, which distinguishes it from other neuropeptides with well-defined GPCRs. Despite this, DSIP exerts reproducible pharmacological effects in in-vivo models, suggesting interaction with existing signalling infrastructure. The prevailing hypothesis involves modulation of GABAergic inhibitory neurotransmission in brainstem arousal circuits (locus coeruleus, raphe nuclei, reticular formation) and hypothalamic sleep-promoting regions (VLPO — ventrolateral preoptic area). Specifically, DSIP may potentiate GABA-B receptor-mediated inhibition of wake-promoting aminergic neurons, shifting the sleep-wake balance toward slow-wave sleep states.

DSIP demonstrates significant resistance to enzymatic degradation relative to other short peptides, partly due to its unique N-terminal tryptophan and the Gly-Gly motif, which reduce susceptibility to aminopeptidase attack. Radiolabelled DSIP crosses the blood-brain barrier (BBB) in preclinical models — a property attributed to receptor-mediated transcytosis or lipophilic interactions — supporting its CNS bioavailability from peripheral administration routes used in rodent research.

At the neuroendocrine level, DSIP inhibits ACTH release from anterior pituitary cell cultures stimulated by CRH, and reduces corticosterone responses in rodent stress paradigms. This HPA-suppressive action is mechanistically separable from sleep promotion and may involve direct pituitary effects or hypothalamic CRH neuron inhibition, positioning DSIP as a multifunctional neuropeptide modulating both sleep homeostasis and stress-axis regulation in research models.

// 02 — Research Findings

Selected Research Findings

Monnier et al. (1977) isolated DSIP from rabbit cerebral venous blood during slow-wave sleep induction and demonstrated that icv infusion of the purified peptide into naive recipient rabbits increased delta EEG power and total slow-wave sleep time, establishing DSIP as the first endogenous sleep-regulatory peptide to be characterised. Monnier et al., Experientia 1977
In rodent chronic stress models, systemic DSIP administration attenuated stress-induced elevations in plasma corticosterone and normalised disrupted sleep architecture (reduced REM latency, restored delta power), suggesting a role in coupling HPA axis regulation with sleep homeostasis under stress conditions. Preclinical chronic stress / sleep models
DSIP administration in rat models of opiate and ethanol withdrawal accelerated normalisation of disrupted EEG delta patterns and reduced withdrawal-associated hyperarousal and anxiety-like behaviour (elevated plus-maze, open field), implicating GABAergic and HPA axis mechanisms in DSIP's apparent stress-resilience properties. Preclinical withdrawal / neuroendocrine models
In aged rodent sleep studies, DSIP treatment restored age-related decline in delta EEG power during NREM sleep, with concurrent improvements in GH pulse amplitude — consistent with the known coupling between slow-wave sleep and somatotropic axis activity and suggesting DSIP as a research tool for studying sleep-GH interactions. Sleep-GH axis models; ageing research
Receptor binding studies using radiolabelled DSIP analogues identified saturable, high-affinity binding sites in hypothalamic, thalamic, and limbic brain regions in rat membranes, consistent with a specific receptor population rather than non-specific membrane interactions — though the molecular identity of this binding site remains uncharacterised. Binding site characterisation studies

Citations last reviewed: 1 October 2026

// 03 — Specifications

As Supplied by BasedPeps

Common name DSIP, Delta Sleep-Inducing Peptide

CAS number 62568-57-4

Molecular formula C₃₅H₄₈N₁₀O₁₅

Molecular weight 849.9 g/mol

Sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu

Receptor Uncharacterised (putative saturable CNS binding sites)

Proposed targets GABA-B; CRH / HPA axis; delta EEG circuitry

Research categories Sleep Biology / Neuroendocrinology / Stress Neuroscience

Supplied as Lyophilised peptide (5 mg vial) and nasal spray solution (10 mL)

Purity ≥99% by HPLC

Storage −20 °C lyophilised; 4 °C in solution, protect from light

Use In-vitro / in-vivo research only — not for human administration

// 04 — FAQ

Researcher FAQ

How was DSIP originally discovered and characterised?

DSIP was isolated by Monnier et al. (1977) from rabbit cerebral venous blood during electrically-induced slow-wave sleep. When infused into naive recipient rabbits, the purified nonapeptide increased delta EEG power and NREM sleep duration, establishing it as the first endogenous sleep-regulatory peptide. Its sequence (Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) was determined shortly after isolation.

Has a specific DSIP receptor been identified?

No high-affinity, molecularly-defined DSIP receptor has been cloned or characterised. Radioligand binding studies show saturable binding sites in hypothalamus, thalamus, and limbic regions, but the molecular identity remains unresolved. This is a key distinction from neuropeptides with well-characterised GPCRs and represents an active area of research uncertainty.

What are the proposed GABAergic mechanisms?

DSIP is hypothesised to potentiate GABAergic inhibition of brainstem arousal circuits — particularly noradrenergic (locus coeruleus) and serotonergic (raphe) wake-promoting neurons — via GABA-B receptor modulation. VLPO sleep-active neurons may also be a target. These mechanisms are inferred from pharmacological and lesion studies rather than direct receptor binding evidence.

How does DSIP affect the HPA axis?

DSIP suppresses CRH-stimulated ACTH release from anterior pituitary cells in vitro and attenuates stress-induced corticosterone elevations in rodent models. This HPA-inhibitory action is studied as a mechanistically distinct property from sleep promotion, making DSIP a research tool for dissecting neuroendocrine-sleep interactions.

How is DSIP supplied for research?

Available as lyophilised DSIP acetate in 5 mg vials and as nasal spray solution in 10 mL format, ≥99% purity by HPLC. For in-vitro and in-vivo preclinical research use only. Not intended for human administration.

Research-Grade DSIP

≥99% purity, lyophilised DSIP acetate. Available as 5 mg vial and 10 mL nasal spray solution for sleep biology and neuroendocrine research.

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