Modulation of memory processing by neuropeptide Y.

Neuropeptide Y (NPY) is a 36 amino acid peptide which occurs in high concentrations in the amygdala and the hippocampus. The studies reported here demonstrate that administration of porcine NPY into the third ventricle of the brain enhanced memory retention for T-maze footshock avoidance and step-down passive avoidance training in mice. Human NPY at 5 micrograms enhanced retention but the inactive free acid form for NPY did not. NPY at 5 micrograms administered subcutaneously did not enhance retention. Post-training administration of NPY produced a dose-dependent, inverted U-shaped dose-response curve for retention of both passive and active avoidance conditioning. NPY enhanced retention in a time-dependent manner. NPY was also found to alleviate the amnesia caused by anisomycin, a protein synthesis inhibitor, and scopolamine, an anticholinergic. Pre-test administration of NPY improved recall but did not affect acquisition. These data support the concept that NPY is a modulator of memory processes.