孕期限食对子代生长发育及卵母细胞印记基因H19甲基化的影响

目的 建立孕期限食的小鼠模型，探究宫内营养不良对子代生长发育及卵母细胞印记基因H19甲基化水平的影响。方法 正常交配见栓的雌鼠随机分为实验组和对照组，d_0.5~d_12.5监测孕鼠每日消耗食物量。实验组小鼠自d_12.5到分娩，给予日常消耗食量的一半食物量，对照组不做任何处理。两组孕鼠在分娩后给予正常食物量。观测子代小鼠的出生数量、出生体重、性别比，同时监测子代小鼠在不同生长时期的体重。子代小鼠性成熟后，取雌鼠的卵母细胞，检测印记基因H19的甲基化水平。结果 （1）孕期限食的母鼠状态差，体型偏小，活动量极少，个别孕鼠在分娩前死亡，早产发生率明显增加（P<0.05）。（2）限食孕鼠的子代小鼠出生体重明显低于正常孕鼠的子代（P<0.05），低体重现象持续至3周龄。3周龄时，限食孕鼠的子代开始了追赶式生长，并在8周龄时，体重明显高于正常子代小鼠（P<0.05）。（3）重亚硫酸盐处理结合限制性内切酶反应结果显示，孕期限食的子代卵母细胞印记基因H19的甲基化水平与对照组一致，未见异常。结论 孕期限食明显增加早产率，并且造成子代低出生体重。在性成熟后，子代有明显的肥胖趋势，但子代卵母细胞印记基因H19甲基化水平正常。

Effect of Intrauterine Malnutrition on Growth Characters and the DNA Methylation Level of H19 of Their Offspring

Objective To establish a mouse model of intrauterine malnutrition to investigate the growth characters and the DNA methylation level of H19 of the offspring.Methods The pregnancy ICR mice were randomly divided into the food restricted group and the control group. The food eaten by each pregnant mouse every day was monitored from d_0.5 to d_12.5. The food restricted pregnancy mice were given half amount food of the daily consumption during d_0.5-d_12.5. The mice in control group were given the normal food. The pregnant mice of both groups of were given normal food after delivery. The number, birth weight and sex ratio of the offspring were calculated. Furthermore, the body weight of the offspring was monitored at different growth stages. The oocytes of female offspring mice were obtained to detect the DNA methylation level of H19.Results (1) Compared to normal feeding pregnant mice,mice with food restricted were small and less active, and even some of them were died before delivery. The incidence of premature birth was significantly increased (P<0.05). The number of abortion, stillbirth pregnant mice in the food restriction group were more than that in the control group, but the difference was not statistically significant (P> 0.05). (2) There was no significant difference in the number of offspring between pregnancy mice with food restricted or normal food (P>0.05). As well as the number of male offspring between the two groups (P>0.05). However, the offspring of the food restricted pregnant mice showed significant low birth weight (P<0.05). (3) At the age of 3 weeks, there was still a low body weight in the offspring of the food restricted pregnant mice, but the difference had no significant difference between groups (P>0.05). After weaning at 3 weeks, the offspring of food restricted pregnant mice began the catch-up growth. At the age of 6 weeks, the body weight of offspring of food restricted pregnant mice was higher than that of the normal offspring, but the difference was not statistically significant (P>0.05). During the period of 6-8 weeks, the weight of offspring of normal feed pregnancy mice was increased slowly. But the body weight of food restriction offspring mice was increased rapidly. At the age of 8 weeks, the body weight of offspring of food restricted group was significantly higher than that in control group (P<0.05). (4) The methylation level of H19 in oocyte from offspring of food restricted pregnancy mice was normal.Conclusion Food restriction at pregnancy period not only affect the outcome of pregnancy, but also increased the rate of premature birth. The offspring of food restriction pregnancy mice showed low birth weight. Until the age of 6 weeks, the offspring of food restriction pregnancy mice had lower body weight compared with the offspring with normal feeding pregnancy mice. The offspring of food restriction pregnancy mice demonstrated obesity at 8 weeks. But the H19 methylation levels of oocytes from offspring of pregnancy mice with food restriction was normal.