Study summary · research use only
The delta EEG (sleep)-inducing peptide (DSIP). XI. Amino-acid analysis, sequence, synthesis and activity of the nonapeptide
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this rabbit study, researchers isolated a peptide from cerebral venous blood dialysate of rabbits given hypnogenic electrical thalamic stimulation and determined its sequence as Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, naming it Delta Sleep-Inducing Peptide (DSIP). They also synthesized 5 possible metabolic products, 2 nonapeptide analogues, and a related tripeptide (Trp-Ser-Glu). All 9 synthetic peptides were infused intraventricularly (6 nmol/kg over 3.5 min) into a total of 61 rabbits including controls under double-blind conditions, with EEG analyzed by fast-Fourier transformation. Synthetic DSIP was associated with a mean 35% increase in EEG delta activity in the neocortex and limbic cortex compared to controls, and the pure alpha-aspartyl form was reported as more active than its beta-Asp isomer. The authors suggested a neurohumoral modulating and programming activity.
Abstract
A peptide which induces slow-wave EEG (sleep) after intraventricular infusion into the brain has been isolated from the extracorporeal dialysate of cerebral venous blood in rabbits submitted to hypnogenic electrical stimulation of the intralaminar thalamic area. It was shown by amino-acid analysis and sequence determination to be Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu and named "Delta Sleep-Inducing Peptide" (DSIP). This compound was synthesized as well as 5 possible metabolic products (1--8, 2--9, 2--8, 1--4 and 5--9), 2 nonapeptide analogues (with one and two amino-acids exchanged) and a related tripeptide (Trp-Ser-Glu). All 9 synthetic peptides were infused intraventricularly in rabbits (6 nmol/kg in 0.05 ml of CSF-like solution over 3.5 min) and tested under double-blind conditions. A total of 61 rabbits including controls were used. The EEG from the frontal neocortex and the limbic archicortex were subjected to direct fast-Fourier transformation and analyzed by an 1108 computer system. A highly specific delta and spindle EEG-enhancing effect of the synthetic DSIP could be demonstrated. The mean increase of EEG delta activity reached 35% in the neocortex and limbic cortex as compared to control animals receiving CSF-like solution or any of the other 8 peptides. The final chemical characterization of the synthetic DSIP revealed that only the pure alpha-aspartyl peptide is highly active in contrast to its beta-Asp isomer. A neurohumoral modulating and programming activity was suggested.
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