Study summary · research use only
Presence of delta-sleep-inducing peptide-like material in human milk
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This human study examined delta-sleep-inducing peptide (DSIP)-like material in breast milk of two women using radioimmunoassay, with about 90% recovery. DSIP-like immunoreactivity (DSIP-LI) was reported at 30 ng/ml in colostrum, decreasing to about 10 ng/ml in milk, with a circadian pattern (afternoon peak, morning trough) found in one woman and a sampling-related difference in the other. Gel chromatography showed most immunoreactive material was larger than the nonapeptide, though intact DSIP was demonstrated by HPLC along with additional immunoreactive peptides; trypsin digestion of the larger material produced a peak coeluting with DSIP. Pregnancy plasma samples showed no difference from normal DSIP values, and no Tyr-MIF-1 or corticotropin-releasing hormone was detected in milk. The authors noted it is unknown whether milk DSIP-LI affects neonatal sleep-wake cycles.
Abstract
Delta-sleep-inducing peptide (DSIP)-like material was detected in human breast milk of two women by RIA with a recovery of about 90%. The high concentration of DSIP-like immunoreactivity (DSIP-LI) in colostrum (30 ng/ml) decreased to about 10 ng/ml in milk. The concentration continued to decrease over the next 2 months in one women. In the same woman, a significant circadian rhythm of the amount of breast milk DSIP was found with the peak in the afternoon and the trough in the morning. A significant effect of the sampling procedure was detected in the other woman examined; lower amounts of DSIP-LI were found when the milk was collected before and higher concentrations after nursing. Gel chromatography revealed that most of the immunoreactive DSIP-LI in milk and colostrum occurred in a form larger than the nonapeptide. The presence of DSIP itself, however, was demonstrated by high pressure liquid chromatography, which also showed additional peptides reacting with the antibody. Digestion of the large immunoreactive DSIP-LI by trypsin produced a peak on Sephadex G-10 that coeluted with DSIP. This peak contained three immunoreactive fractions with retention times on high pressure liquid chromatography similar to DSIP, phosphorylated DSIP, and N-tyrosine-DSIP. Plasma samples taken during pregnancy were assayed for DSIP but no difference from normal values was found. Slightly higher amounts were found in placenta than in blood, which might be due to interfering substances. No Tyr-MIF-1 or corticotropin-releasing hormone was detected by RIA in human breast milk. Peptides and proteins of milk can be absorbed from the gastrointestinal tract of babies, but it is not known if the DSIP-LI in human milk is involved in the induction of a sleep-wake cycle in neonates.
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