[Effects of sevoflurane on brain neuroapoptosis and ability of long-term learning and memory in newborn rats].

Objective: To investigate the changes of neuroapoptosis in brain and learning ability after neonatal mice are exposed to inhaled sevoflurane.

Methods: Twenty-one postnatal day (P) 7 Wistar rats were randomly divided into 7 groups for the preliminary experiment. Arterial blood samples were obtained immediately at the end of anesthesia, then blood analysis was performed. According to the results of the blood analysis, the groups that had no carbon dioxide accumulation were chosen for the following experiment. Ninety postnatal day (P) 7 Wistar rats were randomly divided into 5 groups: group A [sham anesthesia], group B [1% (volume fraction) sevoflurane for 2 h], group C (1% sevoflurane for 4 h), group D [2% (volume fraction) sevoflurane for 2 h] and group E (2% sevoflurane for 4 h). The animals from each group were perfused transcardially with 0.1 mol/L phosphate buffer containing 4% (volume fraction) paraformaldehyde 6 h after the end of anesthesia, and then the brains were exposed for immunohisochemistry, and caspase-3 positive cells were detected. Behavioral studies which included Morris water maze and passive voidance test were performed separately when the rats were 5-week-old, 8-week-old and 14-week-old.

Results: The blood gas data in the mice during the anesthesia showed that the pH, arterial carbon dioxide tension, arterial oxygen tension, and arterial oxygen saturation did not differ significantly from those of the sham controls. The amount of the caspase-3 positive cells in the rat brains of group B, group D and group E was greater than that in group A. When facing the spatial reference memory task or space exploration task, the rats from the different groups made it uniformly. The rats exposed to sham anesthesia had longer latency and less mistake times than those to sevoflurane in passive voidance test when they were 5-week-old, while all the rats had no significant difference in 8 weeks.

Conclusion: Exposure to the concentration of 2% sevoflurane causes brain cell apoptosis of newborn rats. The memory ability to pessimal stimulation is decreased as the anesthesia mice were 5-week-old, such changes recede along with the growth of the rats. Exposure to the concentration of 2% sevoflurane does not affect the spatial reference memory of newborn rats during their growth.