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目的探讨Arc基因表达及甲基化与幼龄鼠和成年鼠空间记忆形成的相关性。方法应用Morris水迷宫对2月龄幼龄鼠和6月龄成年鼠进行定位航行训练,以判断其空间记忆形成情况。采用RT-PCR检测定位航行训练后大鼠海马组织Arc基因mRNA的转录水平,并对海马基因组DNA进行亚硫酸盐处理,采用甲基化特异性聚合酶链反应(Methylation specific polymerase chain reaction,MS-PCR)检测Arc基因的甲基化情况,并进行DNA甲基化序列分析。结果随着定位航行训练入水次序及训练天数的增加,幼龄鼠逃避潜伏期缩短(P<0.05);而成年鼠在训练当天随着入水次序的增加,逃避潜伏期缩短,但第2天逃避潜伏期不仅与入水次序有关,也随着放入点距离的增大,逃避潜伏期相对延长(P<0.05),至第3天逃避潜伏期与入水次序及距离均无关,形成稳定的记忆能力。成年鼠定位航行训练组海马组织Arc基因mRNA的转录水平显著高于正常对照组(P<0.01),且高于幼龄鼠(P<0.05)。与幼龄鼠正常对照组相比,幼龄鼠和成年鼠定位航行训练组第8和24位点均无甲基化,成年鼠定位航行训练组与正常对照组相比,甲基化位点无变化。结论幼龄鼠瞬时记忆能力接近成年鼠,但形成稳定记忆的能力弱于成年鼠。Arc启动子甲基化影响其mRNA的表达,而Arc基因mRNA的转录水平与大鼠空间记忆能力及年龄相关,进一步证实了甲基化参与调解学习和记忆。
Objective To investigate the relationship between Arc gene expression and methylation in spatial memory of young and adult rats. Methods The Morris water maze was used to conduct positioning navigation training on 2-month-old and 6-month-old adult mice to determine the spatial memory formation. RT-PCR was used to detect the mRNA transcription level of Arc gene in hippocampus of rats after navigation training. The hippocampal genomic DNA was subjected to sulfite treatment. Methylation-specific polymerase chain reaction (MS- PCR) to detect methylation of Arc gene and DNA methylation sequence analysis. Results With the increase of water intake and training days, the escape latency of young mice was shortened (P <0.05). However, the escape latency of the adult mice decreased with the increase of inflow sequence on the day of training, but the escape latency on the second day was not only notable It was also related to the order of water intake and the escape latency (P <0.05) with the increase of the insertion point distance. The escape latency was not related to the inflow order and distance by the third day, forming a stable memory ability. The transcriptional level of Arc gene mRNA in hippocampus of adult mouse locomotion training group was significantly higher than that of normal control group (P <0.01), and higher than that of young mice (P <0.05). Compared with the normal control group of young mice, there was no methylation at positions 8 and 24 in the navigation training group of young and adult rats. Compared with the normal control group, No change. Conclusion The transient memory ability of young mice is close to that of adult mice, but the ability to form stable memory is weaker than that of adult mice. Arc promoter methylation affects its mRNA expression, while the transcriptional level of Arc gene mRNA is related to spatial memory ability and age in rats, further confirming that methylation participates in the mediation of learning and memory.