Norepinephrine modulation of social memory: evidence for a time-dependent functional recovery of behavior.

We tested the hypothesis that central nervous system (CNS) norepinephrine (NE) modulates the ability of an adult male rat to remember significant novel stimuli. Behavioral tests evaluated NE effects on general exploration and social memory. Results were that neither depletion nor elevation of NE impaired general exploration. Findings from the social memory setting suggested that animals tested 2 weeks after NE depletion were unable to discriminate novel from familiar juveniles in situations where untreated controls had no difficulty. Elevation of CNS NE, conversely, produced improved discrimination performance compared with control animals. Results suggest that activation of the CNS NE system is involved in the memory for novel stimuli. Performance of the NE-depleted group tested 3 months after treatment indicates a time-dependent functional recovery can occur in the presence of virtually total CNS NE depletion.