Phospho DSIP Information
Phospho-DSIP (phosphorylated delta-sleep inducing peptide) is a nine-amino-acid (nonapeptide) neuropeptide first discovered in 1977 that has been variously demonstrated in published literature to induce sleep, ease opioid and alcohol addiction and withdrawal, act as an analgesic in models of chronic pain, exert various endocrine effects, and potentially act as a stress-limiting factor. However, no gene has been found for DSIP/phospho-DSIP, leading some researchers to question its physiological occurrence altogether. Contradictory results have been published regarding a role in mammals; neither a primary purpose nor the involved receptors have been confirmed. Other investigational areas in which phospho-DSIP has shown promise include as a diagnostic tool in narcolepsy, schizophrenia, and major depressive disorder (MDD); as a possible anticonvulsant in epilepsy; and for restoring normal sleep patterns.
Swiss researchers (Schoenenberger et al) first isolated DSIP in 1977 from the cerebro-venous blood of sleeping rabbits. The amino acid structure of phospho-DSIP is as follows: H-Trp-Ala-Gly-GlyAsp-Ala-Ser(PO3H2)-GlyGlu-OH.  Phospho-DSIP, also called 125I-N-Tyr-P-DSIP, is an analog. Compared to DSIP, phospho-DSIP is stronger in effect and slower to degrade, perhaps in part because it forms complexes with other proteins:
125I-N-Tyr-P-DSIP, a phosphorylated analog, revealed slower degradation and, in contrast to DSIP, produced complex formation. An excess of unlabeled material did not displace the radioactivity supporting the assumption of non-specific binding/aggregation. It was concluded that the rapid disappearance of injected DSIP in blood was due to degradation, whereas complex formation together with slower degradation resulted in longer persistence of apparently intact analogs.
Phospho-DSIP passess through the blood-brain barrier (BBB) more easily than most neuropeptides.
Immunoreactive DSIP has been detected in the hypothalamus, pituitary, and adrenal glands (together comprising the HPA axis) as well as in human infants; this method of detection has shown that in most cases, the DSIP is occurring within a longer (greater than nine aminos) chain or “DSIP-like peptide”. The isolated nonapeptide has shown a variety of effects on the HPA axis when administered exogenously, including inhibiting release of adrenocorticoptropic hormone (ACTH) and reducing circulating levels; stimulating luteinizing hormone (LH) release; and inhibiting the effects of somatostatin (a natural growth-hormone release inhibitor).
In a rat model of epilepsy, DSIP acts as an anti-convulsant.
In opioid withdrawal, DSIP acts as an opioid receptor antagonist; in addition to potentially treating opioid withdrawal, DSIP may be able to prevent further dependence with consistent administration.
Schoenenberger GA, Maier PF, Tobler HJ and Monnier M. A naturally occurring delta-EEG enhancing nonapeptide in rabbits.European Journal of Physiology 369: 99–109. 1977.
Anders Bjartella; Rolf Ekmanb; Frank Sundlerc; Erik Widerlvd. Delta sleep-inducing peptide (DSIP): An overview of central actions and possible relationship to psychiatric illnesses. Nord J Psy, 42:2;111-117. 1988.
Schoenenberger GA. Characterization, properties and multivariate functions of Delta-Sleep Inducing Peptide (DSIP). European Neurology 23: 321–345. 1984.
Iyer KS and McCann SM. Delta sleep inducing peptide (DSIP) stimulates the release of LH but not FSH via a hypothalamic site of action in the rat. Brain Research Bulletin 15: 535–538. 1987.
Kovalzon VM. DSIP: a sleep peptide or unknown hypothalamic hormone?. J. Evol. Biochem. Physiol. 30: 195–199. 1994.
Dragan Hrnia, Olivera Stanojlovia, Dragana ivanovia, Veselinka ušib. Delta-Sleep-Inducing Peptide Potentiates Anticonvulsive Activity of Valproate against Metaphit-Provoked Audiogenic Seizure in Rats. Pharmacology 2006;77:78-84.
Soyka M and Rothenhaeusler H. Delta Sleep-Inducing Peptide Opioid Detoxiﬁcation. Am. J. Psychiat. 154: 714–715. 1997.
 Schneider-Helmert D and Schoenenberger GA. The influence of synthetic DSIP (delta-sleep-inducing-peptide) on disturbed human sleep. Cellular and Molecular Life Sciences 37: 913–917. 1981.
Endogenous sleep substances and sleep regulation. Utrecht, Netherlands: Japan scientific societies press, VNU science press. 1985.
Graf MV, Saegesser B, Schoenenberger GA. Degradation and aggregation of delta sleep-inducing peptide (DSIP) and two analogs in plasma and serum. Peptides. 1987 Jul-Aug;8(4):599-603.
Najimi M, Bennis M, Moyse E, Chigr F. Distribution of delta sleep-inducing peptide in the newborn and infant human hypothalamus: an immunohistochemical study. Biol Res. 2001;34(1):31-42.