Wlodarczyk Bogdan J, Tang Louisa S, Triplett Aleata, Aleman Frank, Finnell Richard H
Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, TX 77030, USA.
Toxicol Appl Pharmacol. 2006 May 15;213(1):55-63. doi: 10.1016/j.taap.2005.09.008. Epub 2005 Oct 14.
Splotch (Sp/Sp) mice homozygous for a mutation in the Pax3 gene inevitably present with neural tube defects (NTDs), along with other associated congenital anomalies. The affected mutant embryos usually die by gestation days (E) 12-13. In the present study, the effect of modifier genes from a new genetic background (CXL-Sp) and periconceptional supplementation with selected micronutrients (folic acid, 5-formyltetrahydrofolate, 5-methyltetrahydrofolate, methionine, myoinositol, thiamine, thymidine, and alpha-tocopherol) was determined with respect to the incidence of NTDs. In order to explore how different exposure parameters (time, dose, and route of compound administration) modulate the beneficial effects of micronutrient supplementation, female mice received either short- or long-term nutrient supplements via enteral or parenteral routes. Embryos were collected on E12.5 and examined for the presence of anterior or posterior NTDs. Additionally, whole mount in situ hybridization studies were conducted in order to reveal/confirm normal expression patterns of the Pax3 gene during neurulation in the wild-type and Sp/Sp homozygous mutant mouse embryos utilized in this study. A strong Pax3 signal was demonstrated in CXL-Sp embryos during neural tube closure (E9.5 to E10.5). The intensity and spatial pattern of expression were similar to other Splotch mutant mice. Of all the micronutrients tested, only supplementation with folic acid or 5-methyltetrahydrofolate rescued the normal phenotype in Sp/Sp embryos. When the folate supplementation dose was increased to 200 mg/kg in the diet, the incidence of rescued splotch homozygotes reached 30%; however, this was accompanied by six-fold increased resorption rate.
斑点（Sp/Sp）小鼠因Pax3基因突变而纯合，不可避免地会出现神经管缺陷（NTDs）以及其他相关先天性异常。受影响的突变胚胎通常在妊娠第12 - 13天死亡。在本研究中，确定了来自新遗传背景（CXL - Sp）的修饰基因以及受孕前补充特定微量营养素（叶酸、5 - 甲酰四氢叶酸、5 - 甲基四氢叶酸、蛋氨酸、肌醇、硫胺素、胸腺嘧啶核苷和α - 生育酚）对NTDs发生率的影响。为了探究不同的暴露参数（时间、剂量和化合物给药途径）如何调节微量营养素补充的有益效果，雌性小鼠通过肠内或肠外途径接受短期或长期营养补充。在妊娠第12.5天收集胚胎，检查是否存在前侧或后侧NTDs。此外，进行了全胚胎原位杂交研究，以揭示/确认本研究中使用的野生型和Sp/Sp纯合突变小鼠胚胎在神经胚形成过程中Pax3基因的正常表达模式。在神经管闭合期间（E9.5至E10.5），CXL - Sp胚胎中显示出强烈的Pax3信号。表达的强度和空间模式与其他斑点突变小鼠相似。在所有测试的微量营养素中，只有补充叶酸或5 - 甲基四氢叶酸能挽救Sp/Sp胚胎的正常表型。当饮食中叶酸补充剂量增加到200 mg/kg时，挽救的斑点纯合子发生率达到30%；然而，这伴随着吸收率增加了六倍。
