To explore neuronal mechanisms underlying long-term consequences of stress, we studied stress-induced changes in the neuritic translocation of acetylcholinesterase (AChE) splice variants. Under normal conditions, we found the synaptic AChE-S mRNA and protein in neurites. Corticosterone, anticholinesterases, and forced swim, each facilitated a rapid (minutes), yet long-lasting (weeks), shift from AChE-S to the normally rare AChE-R mRNA, promoted AChE-R mRNA translocation into neurites, and induced enzyme secretion. Weeks after stress, electrophysiological measurements in hippocampus slices displayed apparently normal evoked synaptic responses but extreme hypersensitivity to both anticholinesterases and atropine. Our findings suggest that neuronal hypersensitivity under stress involves neuritic replacement of AChE-S with AChE-R.