[The hypnogenic effects of delta sleep-inducing peptide (DSIP) analogs: a comparative study in rabbits and rats]

Hypnogenic effects of 3 DSIP analogs with a higher stability against aminopeptidase activity have been studied in rabbits and rats using intraventricular administration (injections and infusions). An analog (D-Ala-2) DSIP augmented slow wave and paradoxical sleep within the 5th, 8th and 11th hours of the recording period. An analog (D-Val-2) DSIP made the same within the 8th and 10th hours, and hexapeptide (D-Ala-2) DSIP (1-6) increased sleep during the 1st, 3rd, and 5th hours. Both nonapeptides augmented sleep in rabbits as well as in rats, though hexapeptide produced this effect in rabbits only, that might be related to some difference in distribution and colocalization of endogenous DSIP-like peptide in the pituitary of two rodent species. It may be suggested that hypnogenic activity of DSIP analogs is determined by the structure of administrated molecule, being mediated by such hormones as GRF and CLIP.