Nicotine modifies in vivo and in vitro rat hippocampal amyloid precursor protein processing in young but not old rats

► Chronic nicotine infusions increased particulate APP in the rat hippocampus in vivo. ► This in vivo response to nicotine was age and regionally selective. ► In vitro, nicotine stimulated the release of secreted APP from hippocampal slices. ► The in vitro effect of nicotine on APP was age-related.