Delta-sleep inducing peptide (DSIP) and its fragments as the modulators of neural transmission in the central nervous system.

The present study is a continuation of our previous experiments on DSIP activity which have revealed that nonapeptide DSIP inhibits hippocampal electrical activity of the 4-7 c/s frequency band. The aim of the present study was to find which of the known DSIP fragments is responsible for its activity, i.e. to find the active site of the molecule. The experiments were carried out with the entire DSIP molecule and its three different fragments. The method of threshold continuous arousal pattern (TCAP) monitoring was used as the indicator of DSIP activity. It was found that the entire DSIP molecule increased TCAP, while its 1-5 fragment decreased it 1-4 and 5-9 fragments had no noticeable effect.