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Product description
DSIP (Delta Sleep-Inducing Peptide) is a nonapeptide with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, which was isolated from the venous blood of the rabbit brain in 1977 by Schoenenberger's group and Monnier in Basel. The peptide received its name due to initial observations suggesting its ability to induce slow-wave (delta) sleep in experimental animals.
Structurally, DSIP is an amphophilic peptide with a molecular weight of 850 Da, characterized by a unique amino acid pattern not assigned to any known peptide family. The molecule shows low molecular stability in vitro with a half-life of approximately 15 minutes due to the action of a specific aminopeptidase. It is suggested that in the body DSIP forms complexes with carrier proteins or exists as a fragment of a larger precursor, although no gene or precursor protein has been identified so far.
DSIP has been detected in both free and bound forms in the hypothalamus, limbic system, pituitary gland and various peripheral organs, tissues and body fluids. In the pituitary, it colocalizes with many peptide and non-peptide mediators, including CLIP, ACTH, MSH, TSH, and MCH. It is also present in secretory cells of the intestines and pancreas, where it colocalizes with glucagon. DSIP-like material has been detected in human breast milk.
Despite almost 50 years of research, the biological function of DSIP remains mysterious. The evidence for its association with sleep patterns is conflicting - some studies suggest the promotion of slow wave sleep and the suppression of REM sleep, while others show no correlation at all. Stronger effects on sleep were observed for synthetic DSIP analogues with greater molecular stability.
Modulation of neurotransmitter synthesis - DSIP affects neurotransmitter levels in the brain by affecting noradrenergic, serotonergic, and dopaminergic pathways. Some studies have demonstrated stimulation of acetyltransferase activity by α1-adrenergic receptors. This modulation may contribute to effects on sleep and mood.
Interaction with NMDA receptors - In the brain, the effects of DSIP may be mediated by NMDA (N-methyl-D-aspartate) receptors, key to the processes of learning, memory and synaptic plasticity. This interaction may explain some of the peptide's neuroprotective effects.
Regulation of the hypothalamic-pituitary axis - Evidence suggests that DSIP is regulated by glucocorticoids and may interact with components of the MAPK cascade. The peptide has homology to the glucocorticoid-induced leucine zipper (GILZ), which prevents Raf-1 activation and inhibits ERK phosphorylation.
Stress-protective effect - DSIP has the ability to counteract stress by modulating the levels of substance P, β-endorphin and corticosterone. In studies on rats subjected to chronic stress, the peptide induced a cascade of molecular reactions that differed in animals with different resistance to emotional stress.
Improves mitochondrial function - Studies have shown that DSIP increases the respiratory control ratio (RCR) and the rate of ADP phosphorylation in brain mitochondria. Under hypoxic conditions, preincubation with DSIP completely inhibited the stress-induced reduction in mitochondrial respiratory activity.
Research on DSIP includes its potential effects on sleep, stress, pain, and metabolic and endocrine functions.
Sleep induction and insomnia
In the first human study in 1983 (Schneider-Helmert and Schoenenberger), intravenous infusion of DSIP (25 nmol/kg) in healthy volunteers caused an immediate feeling of sleep pressure, and total sleep time increased by 59% within 130 minutes after administration. Delayed effects on overnight sleep included shorter time to fall asleep, reduced stage 1 percentage, and improved sleep efficiency. In a double-blind study of 16 patients with chronic insomnia, results indicated higher sleep efficiency and shorter time to fall asleep with DSIP compared to placebo, although the effects were moderate.
Open clinical trials
In an open study of 7 patients with severe insomnia treated with a series of 10 DSIP injections, sleep normalization was achieved in 6 out of 7 people for an observation period of 3-7 months. Improvement in mood and performance during the day was also observed.
Analgesic effect
Pilot clinical trials in patients with chronic pain episodes (migraine, vasomotor headaches, chronic tinnitus, psychogenic pain attacks) showed that DSIP significantly reduced pain levels in 6 of 7 patients after intravenous administration for 5 consecutive days. At the same time, a significant reduction in co-occurring depressive states was observed.
Protection against stress and hypoxia
In studies on rats, preincubation with DSIP (120 μg/kg) before exposure to hypoxia completely inhibited the stress-induced reduction in the respiratory activity of brain mitochondria. The peptide showed the ability to increase the efficiency of oxidative phosphorylation in vitro, which may contribute to the observed stress-protective and antioxidant effects in vivo.
Fusion systems and bioavailability improvement
A 2024 study (Mu et al.) described the development of DSIP fusion peptides with sequences crossing the blood-brain barrier (DSIP-CBBBP) secreted by the yeast Pichia pastoris. In a PCPA-induced insomnia model in mice, the fusion peptides showed the potential to improve sleep and balance neurotransmitter levels.
DSIP remains one of the most enigmatic molecules in neuroscience. Despite almost half a century of research, its physiological role has not been clearly established. The peptide is distinguished by several features:
Historically, DSIP was considered a candidate sleep inducer, but this hypothesis has never been fully confirmed. It is now postulated that the existence of a "DSIP-like peptide" may be responsible for the observed immunoreactivity and biological activity attributed to DSIP.
PubMed
