Characterization of a delta electroencephalogram (sleep) inducing peptide

Abstract

A peptide that induces slow wave (delta) and spindles electroencephalogram enhancement after intraventricular (brain) infusion has been isolated from rabbits and given the name delta-sleep-inducing peptide (DSIP). Amino acid sequence: Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. This compound, five possible metabolic products (containing residues 1-8, 2-9, 2-8, 1-4, and 5-9), two nonapeptide analogues with two amino acids exchanged, and a related tripeptide (Trp-Ser-Glu) were synthesized. All 9 synthetic peptides were infused intraventricularly in rabbits under double blind conditions. A total of 58 rabbits including controls were evaluated. The electroencephalogram leads from the neocortex and the archicortex were directly fast Fourier transformed and analyzed by a Univac 1108 computer system. Only the delta-sleep-inducing peptide (synthetic) showed significant and specific enhancement/induction of delta and spindle electroencephalogram patterns.