Effects Of Sevoflurane Exposure Of Rats In Late Gestation On Performances Of Behavior, Learning And Memory In Their Offspring

Objective To investigate the influences on performances of behaviors, and capability of learning and memory in offspring of rats in late gestation of being exposed to different concentrations of sevoflurane for 6 hours.Methods 15 SD rats at gestational ages of 18 days were randomly divided into 3 groups, namely high concentration of sevoflurane group (group H), low concentration of sevoflurane group (group L) and control group (group C). Pregnant rats in Group H,L and C inhaled 4%(approximately 1.8 MAC for rat), 2%(approximately 0.9 MAC) and 0% sevofluane, in oxygen for 6 hours respectively. Twenty neonates in each group were chosen randomly for next step experiment from the offspring of the pregnant rats receiving sevoflurane inhalation anesthesia. On postnatal day 8 (P8), day 21 (P21) and day 60 (P60), four rats from the 20 neonate chosen previously in each group were chosen randomly every time and euthanatized for pathological examination under HE staining and for detecting synaptophysin and ChAT expression in hippocampus under immunohistochemical staining, the left sixteen neonate received cliff avoidance test from P8 to P14. The left were selected for Open Field test on P21and P60, and for Morris water maze test from P21 to P26 for periodⅠand from P60 to P65 for periodⅡto assess behaviors and capabilities of learning and memory.Results There were no significant differences in neurological behaviors in both Cliff avoidance test and Open field test among three groups(P>0.05). Performances of rats from group H or group L in Morris water-maze test from P21 to P26 showed significantly longer avoidance latency (P<0.05), less time spent in the quadrantⅢwhere the platform was placed in initially(P<0.05), and fewer times of crossing the spot at which platform was located previously(P<0.05) compared with group C. These parameters in Morris water-maze test were tested again on rats from P60～P65 and presented that the results from group H remained obviously different compared with group C, but there was no significant difference in that between group L and group C (P>0.05). The common pathological examination under H E staining did not find anything clearly abnormal in all three groups. The OD values of synaptophysin and the positive cell number of ChAT in hippocampus CA1 of offspring rats from group H were markedly decreased compared with that from group C at all three time points (P<0.05); and the evident differences in values of synaptophysin and ChAT were also indicated between group L and group C on P8 and P21 (P<0.05, respectively), however, were not indicated on P60 (P>0.05).Conclusion Inhalation anesthesia with sevofluane on rats in late pregnancy (day 18) for 6 hours obviously impaired the capability of learning and memory and reduced the expression of SYN or ChAT in hippocampus CA1 area in their offspring. And a duration of the effects of exposure to sevoflurane in high concentration (4%, approximately 1.8 MAC for rat) were rather long, but in low concentration (2%, approximately 0.9 MAC) of sevoflurane were transient. Exposure to these two concentrations in our experiment did not show any impairment on response to a dangerous environment and the adaptation to a new surroundings.