Caspase activity plays an essential role in long-term memory

Activation of intracellular second messenger cascades has been linked to le arning and memory in various organisms. Identification of down-stream targe ts of these second messengers that play a role in learning and memory is an active area of research. Recently, it has been reported that increases in intracellular calcium can activate a cysteine-dependent aspartate-directed protease (caspase) cascade in mice. Using an antibody that selectively reco gnizes activated caspase-3, we detected the presence of this enzyme in hipp ocampal neurons. Inhibition of caspase activity in the hippocampus blocked longterm, but not short-term, spatial memory. These results suggest that a caspase-mediated cellular event(s) in hippocampal neurons is critical for l ong-term spatial memory storage. (C) 2000 Lippincott Williams & Wilkins.