What Is DSIP?

DSIP (Delta Sleep-Inducing Peptide, CAS 62568-57-4, MW 848.81 g/mol) is a synthetic nonapeptide first isolated from rabbit cerebral venous blood in 1977 by the Schoenenberger–Monnier group in Basel. The peptide carries the amino-acid sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu and was originally identified as a candidate humoral sleep factor on the basis of its capacity to promote delta-frequency electroencephalographic activity in rabbits. Decades of preclinical literature have since examined its distribution in neural and peripheral tissue, its electrophysiological signature, and its activity across a broad range of biochemical assays.

This chemistry profile summarizes DSIP’s molecular identity, the documented historical research surrounding its discovery, its structural features as a short linear peptide, and the principal research domains in which it has been investigated. The references at the end of this article link to peer-reviewed primary literature for further reading. ITide Laboratories supplies DSIP exclusively for laboratory research use by qualified investigators; this material is not intended for human, veterinary, diagnostic, or therapeutic use.

Chemical Properties

Historical Development and Discovery

DSIP was first isolated and characterized between 1963 and 1977 at the University of Basel by the laboratory of Marcel Monnier and Guido Schoenenberger. Working with rabbit cerebral venous blood drawn during electrically induced sleep states, the group identified a small peptidic fraction whose intracerebroventricular administration to recipient rabbits reproduced delta-frequency EEG activity. The fully purified nonapeptide was sequenced in 1977 and given the descriptive name “delta sleep-inducing peptide” in reference to the EEG signature observed in the original bioassay.

Following its initial chemical characterization, DSIP became the subject of an extensive preclinical literature spanning the late 1970s through the early 1990s. Comprehensive reviews by Graf and Kastin published in Neuroscience and Biobehavioral Reviews (1984) and Peptides (1986) catalogued the work of this period, describing the nonapeptide’s reported electrophysiological effects, its tissue distribution as detected by radioimmunoassay and immunohistochemistry, and a range of physiological observations made in rabbits, rats, mice, cats, and humans. A 2006 review in the Journal of Neurochemistry by Kovalzon and Strekalova revisited the field and noted that, despite four decades of investigation, the gene encoding a DSIP precursor protein and any cognate receptor remained unidentified, leaving central questions about the peptide’s natural biology open for further research.

Contemporary studies continue to examine DSIP in defined laboratory contexts. A 2021 report published in Molecules investigated intranasal DSIP administration in a rodent middle-cerebral-artery-occlusion model and reported effects on motor coordination scores in the rotarod paradigm. ITide Laboratories supplies research-grade DSIP characterized by HPLC-UV purity, LC-MS identity confirmation, and endotoxin screening for independent laboratory investigators continuing this line of work.

Chemical Architecture and Structural Features

DSIP is a linear nonapeptide with no disulfide bridges, no cyclization, and no post-translational modifications in its synthetic form. The sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu places three glycine residues at positions 3, 4, and 8, contributing to backbone flexibility, while the N-terminal tryptophan provides a single ultraviolet-absorbing aromatic residue that is exploited in HPLC-UV purity assays at 280 nm. The C-terminal glutamate and internal aspartate confer net negative charge at physiological pH, with a calculated isoelectric point in the acidic range.

A phosphorylated variant of DSIP carrying a phosphate group on the serine residue at position 7 (P-DSIP) has been reported in immunological assays of mammalian cerebrospinal fluid. Comparative studies of DSIP-like and P-DSIP-like immunoreactivity in human cerebrospinal fluid have examined the distribution of both forms across age groups and across patient cohorts in published case–control work. The structural distinction between the unphosphorylated and phosphorylated forms remains a point of ongoing interest in DSIP analytical chemistry.

Synthetic DSIP is manufactured by solid-phase peptide synthesis (SPPS), purified by reversed-phase HPLC, and lyophilized for laboratory storage. Identity confirmation is performed by mass spectrometry against the theoretical monoisotopic mass of 848.34 Da (average mass 848.81 g/mol). Each ITide Laboratories lot is independently assayed by a third-party laboratory before release; the certificate of analysis for the current lot is published on the corresponding DSIP COA page.

Research Mechanisms

The molecular target or targets of DSIP have not been definitively established in the published literature. Early electrophysiological work in rabbits and rats reported dose-dependent modulation of cortical EEG patterns and neurotransmitter levels, leading several groups to hypothesize involvement of adrenergic or GABAergic systems, though no cognate receptor has been cloned and characterized to date. The 2006 Kovalzon and Strekalova review proposed the existence of structurally related endogenous peptides that may account for the observed DSIP-like immunoreactivity in mammalian tissues, an interpretation that remains under discussion in the literature.

Radioimmunoassay and immunohistochemistry studies have detected DSIP-like material in the rabbit, rat, pig, and human central nervous system, with particularly strong staining reported in hypothalamic nuclei. DSIP-like immunoreactivity has also been documented in peripheral tissue, including pituitary, adrenal medulla, and gastrointestinal endocrine cells, where it has been observed to co-localize with known peptide hormones in cells of the antral mucosa. The biological significance of this peripheral distribution, and whether it reflects DSIP itself or a closely related molecule, is an open question in DSIP research.

Research Areas

Sleep Architecture and EEG Studies

The original bioassay used to characterize DSIP measured changes in delta-frequency EEG activity in rabbits following intracerebroventricular administration. Subsequent investigations in rats, mice, and cats reported species-dependent effects on sleep-stage distribution, with cats showing predominant changes in slow-wave sleep stage S2 following injection. Investigators have also examined DSIP analogues with modified amino-acid composition for differential EEG activity, and have studied the dose–response relationship of the parent peptide, noting a U-shaped activity curve in several preparations. Sleep architecture work in human research subjects, including small studies in middle-aged adults reporting chronic insomnia, has been published in Experientia.

Neuroendocrine Signaling

DSIP-like immunoreactivity has been detected by histochemistry in neurosecretory hypothalamic nuclei of multiple vertebrate species. This anatomical distribution has prompted research interest in the peptide’s potential role in neuroendocrine signaling, and laboratory studies have examined effects of DSIP infusion on plasma levels of pituitary and adrenal hormones in animal models. The interaction between DSIP and circadian patterning of hormone release has been catalogued in earlier reviews and remains a subject of preclinical research.

Stress and Adaptation Research

Preclinical studies have investigated DSIP in stress-exposure paradigms, including immobilization stress in rodents and post-injury recovery models. Investigators have measured biochemical and behavioral endpoints across these conditions to characterize the peptide’s activity profile. A 2021 study in Molecules examined intranasal DSIP in a rodent focal-stroke model and reported effects on motor coordination scores during a three-week post-injury observation period.

Comparative Peptide Chemistry

DSIP’s short sequence and lack of canonical receptor have made it a subject of comparative peptide chemistry research. Structural analogues with single-residue substitutions, D-amino-acid replacements, and phosphorylated variants have been synthesized and assayed for differential bioactivity in published work. Naturally occurring peptides with partial sequence homology, including a dermorphin-related decapeptide that shares five of nine DSIP positions, have been investigated for related electrophysiological signatures in rabbit and rat models.

Frequently Asked Questions

What is the CAS number for DSIP?

The CAS Registry Number for DSIP is 62568-57-4. This is the unique chemical identifier assigned to the synthetic nonapeptide by Chemical Abstracts Service.

What does DSIP stand for?

DSIP is an acronym for Delta Sleep-Inducing Peptide. The name was assigned by the Schoenenberger–Monnier laboratory in 1977 in reference to the delta-frequency EEG signature observed in the original rabbit bioassay used to isolate the molecule. The acronym is a research descriptor reflecting the discovery context, not a description of the material’s function in any therapeutic setting.

How many amino acids does DSIP contain?

DSIP is a nonapeptide composed of nine amino-acid residues in the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. Its molecular formula is C₃₅H₄₈N₁₀O₁₅ and its molecular weight is 848.81 g/mol.

Is DSIP naturally occurring or synthetic?

DSIP was originally isolated from rabbit cerebral venous blood. The material supplied by ITide Laboratories is produced by solid-phase peptide synthesis, purified by reversed-phase HPLC, and identity-confirmed by LC-MS against the theoretical mass of the natural nonapeptide. Whether the immunoreactive material detected in mammalian tissues represents DSIP itself or a structurally related endogenous peptide remains an open question in the published literature.

What biological systems has DSIP been studied in?

The published literature describes DSIP investigation in rabbits, rats, mice, cats, pigs, and a limited number of human research studies. Tissue distribution studies have examined central nervous system localization (particularly hypothalamic nuclei) as well as peripheral distribution in pituitary, adrenal medulla, and gastrointestinal endocrine cells. Research areas include sleep architecture and EEG signal analysis, neuroendocrine signaling, stress-response models, and comparative peptide chemistry.

Has DSIP been approved for clinical use?

No. DSIP has not been approved by the United States Food and Drug Administration or any equivalent regulatory authority for any clinical indication. The material supplied by ITide Laboratories is for laboratory research use only by qualified investigators and is not intended for human consumption, veterinary use, diagnostic use, or therapeutic use.

What is the molecular weight of DSIP?

The average molecular weight of DSIP is 848.81 g/mol. The monoisotopic mass of the unmodified nonapeptide is 848.34 Da, used by mass-spectrometry-based identity confirmation methods. A phosphorylated variant carrying a phosphate group on the serine at position 7 (P-DSIP) has an additional mass of approximately 80 Da and is reported in some immunoreactivity studies.

Where can I find the certificate of analysis for this lot?

The current ITide Laboratories DSIP lot has been independently assayed by Freedom Diagnostics. The full HPLC-UV chromatogram, LC-MS identity confirmation, endotoxin screen, and chain-of-custody information are published on the DSIP certificate of analysis page. The corresponding product page is available at DSIP product.

Published Research

According to PubMed, the following peer-reviewed publications represent key entries in the DSIP literature and are recommended starting points for further reading. Inclusion does not imply endorsement of any conclusion; references are provided to allow independent investigators to evaluate the primary literature directly.

1. Kovalzon V M, Strekalova T V. Delta sleep-inducing peptide (DSIP): a still unresolved riddle. Journal of Neurochemistry. 2006;97(2):303–309. DOI: 10.1111/j.1471-4159.2006.03693.x
2. Graf M V, Kastin A J. Delta-sleep-inducing peptide (DSIP): an update. Peptides. 1986;7(6):1165–1187. DOI: 10.1016/0196-9781(86)90148-8
3. Graf M V, Kastin A J. Delta-sleep-inducing peptide (DSIP): a review. Neuroscience and Biobehavioral Reviews. 1984;8(1):83–93. DOI: 10.1016/0149-7634(84)90022-8
4. Tukhovskaya E A, Ismailova A M, Shaykhutdinova E R, et al. Delta sleep-inducing peptide recovers motor function in SD rats after focal stroke. Molecules. 2021;26(17):5173. DOI: 10.3390/molecules26175173
5. Susić V, Masirević G, Totić S. The effects of delta-sleep-inducing peptide (DSIP) on wakefulness and sleep patterns in the cat. Brain Research. 1987;414(2):262–270. DOI: 10.1016/0006-8993(87)90006-0
6. Schneider-Helmert D, Schoenenberger G A. The influence of synthetic DSIP (delta-sleep-inducing-peptide) on disturbed human sleep. Experientia. 1981;37(9):913–917. DOI: 10.1007/BF01971753
7. Bjartell A, Ekman R, Hedenbro J, Sjölund K, Sundler F. Delta sleep-inducing peptide (DSIP)-like immunoreactivity in gut: coexistence with known peptide hormones. Peptides. 1989;10(1):163–170. DOI: 10.1016/0196-9781(89)90093-4
8. Ernst A, Cramer H, Strubel D, Kuntzmann F, Schoenenberger G A. Comparison of DSIP- and P-DSIP-like immunoreactivity in cerebrospinal fluid of patients with senile dementia of Alzheimer type, multi-infarct syndrome, communicating hydrocephalus and Parkinson’s disease. Journal of Neurology. 1987;235(1):16–21. DOI: 10.1007/BF00314191
9. Pollard B J, Pomfrett C J. Delta sleep-inducing peptide. European Journal of Anaesthesiology. 2001;18(7):419–422. DOI: 10.1046/j.1365-2346.2001.00917.x

Citations sourced from PubMed.

Research Use Only Disclaimer

FOR RESEARCH USE ONLY. NOT FOR HUMAN CONSUMPTION. NOT FOR VETERINARY OR ANIMAL USE. NOT FOR DIAGNOSTIC USE. NOT FOR THERAPEUTIC USE.

This material is supplied exclusively for laboratory research purposes by qualified professionals. It has not been evaluated or approved by the United States Food and Drug Administration for any clinical use. Possession and handling are restricted to environments equipped for the safe storage and use of research-grade chemical materials. Purchasers represent that they are 18 years of age or older and that the material will be used only for the stated research purposes. The information presented on this page summarizes peer-reviewed scientific literature and is intended for use by qualified investigators evaluating the published record. Nothing on this page is medical advice, a therapeutic claim, or an invitation to use the material outside a laboratory research setting.