Sevoflurane Anesthesia Does Not Impair Acquisition Learning or Memory in the Morris Water Maze in Young Adult and Aged Rats

Background: Sevoflurane has been found to increase apoptosis and pathologic markers associated with Alzheimer disease, provoking concern over their potential contribution to postoperative cognitive dysfunction. Methods: The effects of anesthesia with 1 minimum alveolar concentration of sevoflurane for 4 h or sham exposure on cognition were investigated in young adult and aged (20-24 months) rats at 1, 4, and 12 weeks postexposure. Spatial reference memory acquisition and retention were tested in the Morris water maze task. Latency to locate the hidden platform and swim speed were determined and compared between treatments. Results: Sevoflurane anesthesia significantly reduced latency to find the hidden platform in both young adult (n = 10 per treatment, P < 0.0001) and aged rats (n = 7 per treatment, P < 0.0001) when tested 1 week after exposure. In young rats only, this improved acquisition learning was maintained at 4 (P = 0.003) but not at 12 weeks postexposure (P = 0.061). There were no differences in swim speed or in open field exploration between groups (no confounding effects of stress or locomotion). Retention memory measured using probe trials was not affected by exposure to sevoflurane in young adult or aged rats. Conclusion: Sevoflurane anesthesia did not impair acquisition learning and retention memory in young adult or aged rats.