[Function of HCNP/HCNP precursor in memory formation].

Based on the hypothesis of target-derived trophic factor, we have purified a novel peptide from young rat hippocampus, named Hippocampal Cholinergic Neurostimulating Peptide: HCNP, which induces the synthesis of acetylcholine in the medial septal nucleus. This peptide is aligned with the N terminal of protein composed 186 amino acids (HCNP precursor protein), and released from neurons in hippocampus by the NMDA receptor stimulation. Moreover, HCNP precursor can be involved in neural activity in hippocampus via the inhibition of phosphorylation of Erk. HCNP and its precursor can be a candidate for the key molecules elucidating the underlying association among Abeta, phosphorylated tau, degeneration of dendritic spine and decrease of acetylcholine in Alzheimer brain.