Convulsant peptides related to corticotropin-releasing factor (CRF).

Corticotropin-releasing factor (CRF) and its related peptides have some conserved primary regions. We have taken an interest in the characteristic conserved sequence, Pro-Pro-Ile-Ser, which is located in the proximal N-terminal region of the CRF family. This sequence is not included in any other biologically active peptide and protein. Biological function of this N-terminal region has not become known yet. We synthesized seventeen peptide fragments of human CRF and sauvagine which involved either this entire N-terminal sequence or part of it and determined their behavioural effect after intracerebroventricular injections to mice. Several peptides which included the Pro-Pro-Ile region as the N-terminal segment and their caused a transient convulsion dose-dependently. H-Pro-Pro-Ile-OH (human CRF(4-6)) exhibited the strongest effect among these active peptides. However, these convulsant peptides did not affect the secretion of immunoreactive corticotropin in rats.