The long-term effects of sevoflurane given by different concentration and time course on cognitive function and expression of hippocampus brain derived neurotrophic factor in neonate rats

Objective To investigate the long-term effects of sevoflurane given by different concentration and time course on cognitive function and expression of hippocampus brain derived neurotrophic factor(BDNF)in neonatal rats.Methods SD rats at seven-day-old were randomly divided into 4 groups.Rats only inhaled oxygen as control(group C)or inhaled sevoflurane at 5.1％ for 1.3 h(group S),at 3.4％ for 2 h(group M)and at 1.7％ for 4 h(group L).Each group has 20 rats.Open field test and novel obiect recognition test were used to assess the cognitive function of the rats at 28-day-old.Then these rats were killed and measurede the expressions of BDNF and BDNF mRNA using immuno-histochemistry and reverse transcriptive polymerase chain reaction(RT-PCR)in hippocampus respectively.Results ① In all tests,there was no significant change between group S and group C(P＞0.05).② Group M didn't not exhibit significant difference in comparison with group C in every item of the open field test.In the novel obiect recognition test,the percentage of exploring time on new object of group M in 24th hour was 63.4％,which showed significantly lower than controls 69.8％(P＜0.05).The average optic density of BDNF(0.229±0.021)and the relative value of BDNF mRNA(0.775±0.024)of hippocampus of group M were both lower than(0.0251 ±0.020)and(0.799±0.023)of control C respectivly(P＜0.05).③ No matter the tests of cognitive function or expressions of BDNF and BDNF mRNA,each index of group L was worse than group C and group M (P＜0.05).Conclusion sevoflurane can induce forward cognitive decline in neonate rat,that may be because of decreasing the expression of BDNF in hippocampus.The time of inhaleing sevoflurane was an important reason. Key words: Sevoflurane;  Hippocampus;  Cognition function;  Brain derived neurotrophic factor