Synthetic Delta Sleep-inducing Peptide Research Articles

Extraction and immunochemical characterization of delta sleep-inducing peptide-like material from the porcine pituitary and adrenal gland

The naturally occurring forms of delta sleep-inducing peptide (DSIP) are not fully identified. In the present study, porcine pituitaries and adrenal glands were extracted in water, saline or acid under various conditions and immunoreactive DSIP (IR-DSIP) quantified by radioimmunoassay. The highest concentrations were measured in anterior pituitary extracts (40.8±2.6 ng/g tissue weight) recovered using water with aprotinin. However, high performance liquid chromatography (HPLC) indicated degradation of hydrophobic forms of IR-DSIP in water extracts. Extraction in acetic acid including C18 Sep-Pak® purification resulted in an elution profile of IR-DSIP in adrenal extracts with a major peak coeluting with synthetic DSIP [DSIP(1–9)], whereas anterior pituitary extract showed material of higher hydrophobicity. Approximately 30% of IR-DSIP in anterior pituitary as well as in adrenal gland extracts seemed to be glucosylated, as based on concanavalin A chromatography. One of the DSIP-immunoreactive components by immunoblotting (molecular mass 25 kDa) was identified in both pituitary and adrenal gland extracts. In conclusion, several chromatographically distinct forms of IR-DSIP are present in the porcine pituitary and adrenal gland. IR material eluting as DSIP(1–9) is present in adrenal gland extract. The procedure and solution used for tissue extraction seem to be essential in order to obtain reliable elution positions on HPLC.

Immunoreactive Delta Sleep-Inducing Peptide in the Rat Hypothalamus, Pituitary and Adrenal Gland: Effects of Adrenalectomy

Immunoreactive (IR) delta sleep-inducing peptide (DSIP) was examined by immunocytochemistry in the rat pituitary and adrenal gland and found to be colocalized with IR thyroid-stimulating hormone in the pituitary and with noradrenaline in the adrenal medulla. IR-DSIP was also detectable in nerve fibers in the posterior pituitary. By radioimmunoassay, IR-DSIP was quantified in plasma and tissue extracts after uni- or bilateral adrenalectomy. Significantly elevated plasma levels of IR-DSIP were measured 5 days after bilateral adrenalectomy (p less than 0.001). IR-DSIP was increased (p less than 0.05) in pituitary extracts from bilaterally adrenalectomized rats after 5 days, but not after 14 or 28 days. Sham- and unoperated animals did not significantly differ in plasma or tissue concentration of IR-DSIP. High-performance liquid chromatography of C18 SEP-PAK purified hypothalamus extracts revealed a single peak of IR-DSIP material of lower hydrophobicity than synthetic DSIP. The elevated concentration of IR-DSIP in the rat pituitary and plasma after bilateral adrenalectomy is consistent with the previously suggested role of DSIP to influence the activity of the hypothalamic-pituitary-adrenal axis.

Delta sleep-inducing peptide (DSIP)-like immunoreactivity in gut: Coexistence with known peptide hormones

Delta sleep-inducing peptide-like immunoreactivity (DSIP-LI) has previously been demonstrated in brain neurons and in endocrine cells of the pituitary and the adrenal medulla. By means of three different antisera against synthetic DSIP we now describe the occurrence and distribution of DSIP-LI in several gut endocrine cells. The human gut was the richest source, where DSIP-LI was located in gastrin/CCK, secretin and PYY/glicentin cells. The rat and pig gut harbour a moderate number of immunoreactive cells in the antral mucosa but in the intestines DSIP-LI-containing cells were very few. By radioimmunoassay, the concentration of DSIP-LI was determined in extracts of various gut regions from man, pig and rat. The highest concentrations were found in all human specimens compared with corresponding samples in the pig and rat. In all three species, high-performance liquid chromatography revealed a single peak of DSIP-like material with approximately the same retention time as DSIP 3-9. Taken together, the present results provide evidence for the presence of DSIP-LI in gut endocrine cells in man, pig and rat; the human gut seems to be the richest source of DSIP-like peptides.

Purification and characterization of DSIP-like material from ovine pineal glands: possible peptide-protein interaction.

The nonapeptide delta-sleep-inducing peptide (DSIP) has been isolated from venous blood of rabbits induced to sleep. Numerous reports have described sleep as well as extra-sleep effects. Radiochemical and immunochemical data suggest a relationship of DSIP with the pineal gland supported by interactions of this peptide with pineal functions such as the serotonin N-acetyltransferase activity. In order to demonstrate the natural occurrence of DSIP-like material associated with high Mr proteins in the ovine pineal, organs were water-extracted and fractionated by ultrafiltration and gel filtration. Radioimmunoassay (RIA) for DSIP-like fragments of the fractions revealed considerable amounts of pineal DSIP-like immunoreactivity (DSIP-LI) apparently existing in small as well as large molecular forms. Acidification of large DSIP-LI forms resulted in the elution from Sephadex G-50 of Mr less than or equal to 1,000 DSIP-like material. This free DSIP-LI form coeluted with the synthetic DSIP nonapeptide from microBondapak C18 on high-performance liquid chromatography. The results, therefore, appear to indicate the presence of a (biospecific) noncovalent intermolecular interaction of DSIP (1-9) with proteins (Mr greater than or equal to 10,000) of the ovine pineal gland.

Immunoreactive delta sleep-inducing peptide in pituitary adrenocorticotropin/alpha-melanotropin cells and adrenal medullary cells of the pig.

Immunoreactive delta sleep-inducing peptide (DSIP) is known to occur in the central nervous system and in body fluids including cerebrospinal fluid, blood and urine. However, the exact nature of the immunoreactive material demonstrated has been a matter of discussion. In the present study, DSIP-like immunoreactivity was demonstrated in the porcine pituitary and adrenal medulla using radioimmunoassay and immunocytochemistry. In the pituitary, the DSIP-like material was present in a subpopulation of the cells storing adrenocorticotropin and alpha-melanotropin. The DSIP immunoreactive cells in the adrenal medulla were identical with a major population of the noradrenaline-storing cells. High-performance liquid chromatography of tissue extracts revealed one major peak of DSIP-like immunoreactivity which did not coelute with synthetic DSIP. The immunoreactive material may represent N-terminally truncated fragments of DSIP. The present results suggest that the anterior and intermediate lobes of the pituitary and the adrenal medulla are potential sources of DSIP-like peptides.

Increased sleep following intracerebroventricular injection of the delta sleep-inducing peptide in rats

Synthetic delta sleep-inducing peptide (DSIP) was injected intracerebroventricularly into rats in a dose of 7 nmol/kg. A significant, 20% increase in total slow wave sleep (and total sleep) was found in the DSIP-injected rats, compared to a baseline recording following a sham injection procedure. Rats injected with the Ringer solution vehicle did not change their sleep compared to their baseline recording.

Synthesis of delta sleep-inducing peptide (DSIP) and its physiological activity.

Protected nonapeptide--Delta Sleep-Inducing Peptide (DSIP) formula: see text has been synthesized by classical method. The product has been treated with TFA and purified on DEAE-Sephadex-A25 column, pure free nonapeptide obtained and alpha to beta transposition of Asp-residue found to be absent. It has been assayed by electrophoresis at pH 3.8, microcrystallinecellulose TLC and HPLC. The physiological activities of synthetic DSIP are performed on rabbits by using intravenous administration or mesodiencephalic ventricular infusion. Its function of intensifying delta and sigma waves on rabbit's electroencephalogram (EEG) is evident. There is no concomitant increase of delta- and sigma-enhancing effect following mesodiencephalic ventricular infusion of 10 or 20 times higher than 5 microgram/rabbit doses. Results of 6-day consecutive intravenous administration (50 microgram/kg) indicate that there is no obvious sign of adaptation to DSIP. Results suggest that the physiological function of endogenous sleep-inducing peptide is different from that of general sleeping draught.

Transport of the synthetic peptide DSIP through the blood-brain barrier in rabbit.

The synthetic delta sleep inducing peptide (DSIP) passes the blood-brain barrier, since i.v. injection in free moving rabbits (30 nmoles/kg) significantly increases the cortical delta activity and decreases the motor activity during 5 h.

Delta sleep-inducing peptide (DSIP): EEG and motor activity in rabbits following intravenous administration

The synthetic delta sleep-inducing peptide (DSIP), a monapeptide, was injected intravenously in free moving rabbits (30 nmol/kg). In EEG tests, a significant increase in delta activity occurred within 5 h after injection of DSIP. Motor activity recorded simultaneously showed a slight concomitant decrease. These EEG and behavioral effects confirmed that DSIP also induces, when intravenously injected, orthodox slow wave sleep.