Demonstration of the biological activity of peptide fragments related to human and rat hippocampal cholinergic neurostimulating peptide (HCNP).

Human and rat hippocampal cholinergic neurostimulating peptides (HCNPs) are 54.5% homologous; both stimulate acetylcholine synthesis in rat medial septal nuclei cultures. This in vitro system was used to test the bioactivity of short peptides containing human or rat HCNP sequences. Peptides with sequences corresponding to the N-termini and middle regions of both, and to the shared three C-terminal residues were not active. Tetrapeptides and hexapeptides whose C-terminus is this common sequence enhanced acetylcholine production, indicating that the minimum consensus sequence for HCNP activity is X-Gly-Pro-Leu.