Interaction of teratogens in heart development

锥干和神经管缺陷之间众所周知的关系的生物学基础，现在通常被认为是在他们的原始细胞的共同起源。然而，对于导致这些缺陷的机制还没有达成共识。高水平的保护提供了保护锥干，其他神经嵴，和神经管缺陷的叶酸补充剂，这意味着一个无名的过程非常重要的是敏感地依赖于足够的叶酸供应。对于目前的建议，我们将测试的假设，即同型半胱氨酸是一种致畸剂的圆锥干和其他衍生物的神经上皮细胞，叶酸补充剂提供保护胚胎通过降低同型半胱氨酸的浓度可以诱导异常发育的圆锥干和其他神经嵴/神经管衍生物作为一种NMDA受体（NMDA）拮抗剂。 通过这种机制，同型半胱氨酸可能与其他NMDA拮抗剂相互作用，加剧致畸作用;相反，可以预测，激活NMDA将拯救暴露于同型半胱氨酸和相关化合物的胚胎。以下具体目标将检验这一假设。目的1，确定外源性NMDA拮抗剂如何与同型半胱氨酸相互作用，加剧正常发育的破坏。目的2，测量NMDA的激活可以挽救用同型半胱氨酸和相关化合物处理的胚胎的程度。目的3分析同型半胱氨酸和其他NMDA拮抗剂处理后胚胎基因表达的变化。意义这一建议提供了第一个统一的假说，关于一个机制，为一个大的一套危险因素的异常发展，其共同的影响是抑制NMDA的功能。这些可能包括治疗药物、娱乐药物、环境污染物和营养不良的后遗症。一个共同的作用机制将使这些因素以以前未曾预料到的方式相互作用，可能会加剧其各自的影响。通过了解这种互动机制，可以实现有效和全面的预防战略。

The biological basis for well-known relationships among conotruncal and neural tube defects is now generally assumed to be found in the common origin of their primordial cells. However, there is no consensus about the mechanism that leads to these defects. A high level of protection of protection is offered for conotruncal, other neural crest, and neural tube defects by folic acid supplementation, implying that an unnamed process of extraordinary importance is sensitively dependent upon an adequate supply of folic acid. For the present proposal, we will test the hypothesis that homocysteine is a teratogen for the conotruncus and other derivatives of the neuroepithelium; and that folic acid supplementation provides protection for embryos by reducing the concentration of homocysteine can induce abnormal development of the conotruncus and other neural crest/neural tube derivatives by acting as an NMDA receptor (NMDA) antagonist. By this mechanism, homocysteine may interact with other NMDA antagonists to exacerbate the teratogenic effect; conversely, it may be predicted that activation of the NMDA would rescue embryos exposed to homocysteine and related compounds. The following specific aims will test this hypothesis. Aim 1, to determine how exogenous NMDA antagonists may interact with homocysteine to exacerbate the disruption of normal development. Aim 2, to measure the degree to which activation of the NMDA may rescue embryos that are treated with homocysteine and related compounds. Aim 3, to analyze changes in gene expression in embryos treated with homocysteine and other NMDA antagonists. SIGNIFICANCE. This proposal offers the first unifying hypothesis regarding a mechanism for a large set of risk factors for abnormal development whose common effect is to inhibit the function of the NMDA. These may include therapeutic drugs, recreation drugs, environmental pollutants, and sequelae of malnutrition. A common mechanism of action would permit these factors to interact in previously unsuspected ways, potentially to exacerbate their respective effects. Effective and comprehensive prevention strategies may be achieved through understanding of such interactive mechanisms.