基因芯片技术筛选孕期缺锌仔鼠脑中差异表达基因

SCANNING DIFFERENTIAL EXPRESSION GENES IN THE BRAIN OF OFFSPRINGS WITH ZINC DEFICIENCY DURING PREGNANCY

目的: 探讨母鼠在孕期和哺乳期缺锌对仔鼠成年后脑功能特别是学习记忆能力的影响,考察孕期缺锌母鼠所产仔鼠脑内基因的差异表达状况并筛选相关差异表达基因。方法: 怀孕ICR雌鼠24只随机分为(A)对照组,(B)孕期及哺乳期轻度缺锌组,(C)孕期严重缺锌组。对照饲料、轻度缺锌饲料及缺锌饲料的锌含量分别为100 mg/kg、5 mg/kg和1 mg/kg。仔鼠断乳后饲喂普通市售饲料。A、B组仔鼠70日龄(P70)后以穿梭箱法测试仔鼠的学习记忆能力,并制备海马脑片检测仔鼠长时程增强(LTP)变化情况;以A组仔鼠作对照,基因芯片技术检测C组仔鼠(P1)脑中差异表达基因。结果: C组仔鼠出生后即死亡。行为测试中,B组仔鼠达到学习标准所需次数多于A组仔鼠,二者有显著性差异;B组仔鼠海马脑片诱导的LTP低于A组仔鼠;基因芯片检测初步确认C组仔鼠脑中有8条差异表达基因(A组仔鼠作对照,表达差异2倍以上),其中5条锌上调序列,3条锌下调序列。结论: 孕期及哺乳期轻度缺锌即可造成仔鼠成年后学习记忆能力下降,同时也影响海马的突触可塑性,故孕期是锌缺乏造成脑功能损伤的关键时期;孕期缺锌引发的仔鼠成年后脑功能损伤可能与神经细胞Ras-MAPK信息传递途径中MAPKK2表达紊乱有关。

Objective: To explore the effects of zinc deficiency during pregnancy and lactation of maternal mice on learning ability and hippocampal long-term potentiality of adult offspring, and to screen differential expression genes in zinc deficient offspring during pregnancy. Methods:Twenty-four pregnant ICR mice were randomly divided into three groups. Group A (control) and group B were fed with control diet (Zn 100mg/kg) and moderate zinc deficient diet (Zn 5mg/kg) respectively during pregnancy and lactation, and group C was fed with zinc deficient diet (Zn 1mg/kg) during pregnancy. The offsprings from group A and group B were fed with normal diet after weaning (P21). The induction of long-term potentiality (LTP) on the hippocampus slices of groups A and B offspring was investigated after behavioral experiment with shuttle box. cDNA array technique was adopted to scan differential expression genes in the newborn offspring(P1) of group C with offspring of group A as control( the nylon membrane arrays containing 14000 partial cDNAs or ESTs of human). Results:The number of trials needed to reach the learning criterion in group B was signaficantly higher than that in group A; LTP induced in brain slices in group B was smaller than that in group A; of 8 pieces of cDNA sequences showing 2-fold change expression, 5 pieces upregulated and others downregulated by dietary zinc deficiency. Conclusions: Moderate zinc deficiency during pregnancy and lactation could induce lower learning ability and synaptic plasticity of the adult offspring. Differential expression genes obtained by cDNA array reveal that the defect of brain function resulted from zinc deficiency is supposed to be associated with disturbance of MAPKK2 expression in Ras-MAPK signal transduction pathway. Further study of these obtained genes will be helpful to understand the role of zinc in brain function.