| Objiective:To investigate the effects and mechanism of enflurane anesthesia on the learning and memory function of SD rat's offsprings'during early pregnancy.Methods:Thirty healthy SD rats aged 3 months weighing 0.2-0.25kg were randomly assigned to control group (group c, n=10), enflurane ahesthesia 4 hours group (group E1, n=10) and enflurane anesthesia 8 hours group (group E2, n=10). On the 5 to 7days of gestation, enflurane anesthesia was given. The offsprings of the rats were randomly divided into 20 days and 30 days subgroup according to the postnatal time. The learning and memory function of offsprings were analyzed by Morris water maze. After Morris water maze experiment, the offsprings were sacrificed. Reverse transcription polymerase chain reaction and immunohistochemical methods were used to detect the expression levels of N-methyl-aspartate receptor 2B (NR2B) and Hippyragranin (HGN) in the offsprings'hippocampus.Result:Compared with control group, the escape latency of the offsprings'in group El and group E2 increased significantly (P<0.05). Twenty days postnatal, the numbers of crossing the platform by the offsprings in group C, Group E1 and E2 were 2.9±0.7,1.7±0.4 and 1.8±0.5 respectively. Thirty days postnatal, the numbers of crossing the platform by the offsprings in group C, Group El and Group E2 were 2.5±0.7,1.7±0.5 and 1.6±0.5 respectively. Twenty days postnatal, the time of traveling in second quadrant by the offsprings in group C, Group E1 and E2 were 30.0±3.2,25.1±2.1 and 26.6±2.4 respectively. Thirty days postnatal, the time of traveling in second quadrant by the offsprings in group C, Group E1 and E2 were 29.3±3.5,26.5±2.0 and 26.1±2.2 respectively. Compared with control group, the second quadrant activity time in Group E1 and Group E2 are significantly reduced (P <0.05). Twenty days postnatal, the expression levels of NR2B protein in the offsprings'hippocampus in group C, Group E1 and E2 were 0.7119±0.07, 0.6414±0.069,0.6345±0.071 respectively. Thirty days postnatal, it was 0.6741±0.045,0.6161±0.0808 and 0.5806±0.0509 respectively. Twenty days postnatal, the expression levels of NR2B mRNA in the offsprings'hippocampus in group C, Group E1 and E2 were 0.7119±0.07,0.6414±0.069 and 0.6345±0.071.Thirty days postnatal, it were 0.6741±0.045,0.6161±0.0808 and 0.5806±0.0509 respectively. Compared with control group, the expression levels of NR2B protein and NR2B mRNA in group El and group E2 were significantly reduced (P<0.01 or p<0.05). Twenty days postnatal, the expression levels of HGN mRNA in the offsprings' hippocampus in group C, Group E1 and group E2 were 0.565±0.07,0.589±0.046 and 0.600±0.068 respectively. Thirty days postnatal, they were 0.589±0.04,0.601±0.0629 and 0.612±0.521 respectively. Compared with control group, the expression levels of HGN mRNA in group E1 and Group E2 has increasing trend with prolonged exposure to enflurane, but there were no significant differences (P>0.05). Twenty days postnatal, the ratio of NR2BmRNA/HGNmRNA in group C, Group E1 and group E2 were 1.26±0.17,1.10±015,1.09±0.17 respectively. Thirty days postnatal, it were 1.04±0.19,1.01±0.13 and 1.17±0.12 respectively. Compared with group C, the ratio of NR2BmRNA/HGNmRNA in Group E1 and group E2 decreased significantly (P<0.05).No significant differences could be seen in these indices between group E1 and group E2 (P>0.05)Conclusion:Under the experimental condition, enflurane anesthesia could damage the spatial learning and memory function of the rat's offsprings'. The mechanism is enflurane during the early stage of gestation can down-regulate expression of learning and memory positive regulation factors NR2B,thus to potentiate the expression of negative regulation factors HGN in the rat's offsprings' hippocampus, therefor disrupting the balance between the learning and memory positive regulation factors NR2B and it's negative regulation factors HGN in the rat's offsprings'hippocampus. The mechanism of NR2B regulating the expression of HGN needs further study. |
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