Early experience influences adult retention of aversively motivated tasks in normal, but not DSP4‐treated rats

Sprague‐Dawley rat pups were injected with DSP4 or water within 48 hr of birth and tested as adults in an inhibitory avoidance task and in a Y‐maze discrimination reversal task. Half of the animals were also tested as juveniles during postnatal weeks 4–5, in tasks assessing odor preferences and general investigatory behavior. Controls, but not drug‐treated adults, which received the juvenile testing, showed significantly better retention on both tasks than either controls or drug‐treated animals not tested as juveniles. Neonatal DSP4 significantly reduced norepinephrine concentrations in the hippocampus and frontal cortex, but not the heart. The results suggest that central norepinephrine may modulate the effects of early experience on adult learning.