OMEGA-3 FATTY ACIDS AND VISUAL DEVELOPMENT

描述：大多数婴儿配方奶粉提供充足的α-亚麻酸（LNA） 但配方奶喂养的婴儿有患二十二碳六烯酸（DHA）的风险， 由于其代谢这种长链的能力有限， 多不饱和脂肪酸（LCP）的LNA在生命的第一个月。 配方奶喂养的婴儿红细胞脂肪酸组成异常， 与母乳喂养的婴儿相比， 通过人乳预先形成的DHA。 配方奶粉喂养的婴儿，他们的饮食缺乏这两个 LNA和DHA表现出较不敏感的视杆视网膜电图（ERG）功能， 皮质视觉诱发电位（VEP）敏锐度较差， 偏好外观（PL）敏锐度，Fagan和Bayley得分较低 试验. 早产儿和足月儿对膳食DHA的特殊需求是 在当前资助期间的研究重点和PI中期结果 支持DHA对视觉功能最佳成熟的重要性。 1. 为了描述DHA在支持最佳成熟中的作用， 皮质功能 VEP，特别是PL敏锐度已被广泛用作 皮质或中枢神经系统的一般成熟指数; 这些研究的动机一直是量化微妙的 与神经膜的LCP组成有关的差异。 PI建议 一系列研究通过随机的 点立体视锐度和认知功能测试在39周，4 年和9岁。 这些数据，加上VEP和PL敏锐度数据， 也将被用来检验假设的有效性，即VEP和PL 敏锐度通过分析同时发生的 和认知表现的预测效度。 2. 评估早期营养不良后是否需要补充膳食 断奶 根据我们的数据，支持DHA在 在长期饮食中，我们将讨论DHA是否是必不可少的问题， 断奶后饮食。 在美国的常见做法是一个简短的6-8周的时间， 母乳喂养;但初步证据表明， DHA是至少17周的必需品。 这项研究将是第一次测试 DHA在断奶后饮食中的重要性， 随机试验 3. 为了评估DHA在神经系统中的功能作用， 人类婴儿的视网膜膜。 虽然有一些 关于DHA在脊椎动物神经膜中的作用的研究很少 已知DHA在人类婴儿神经膜中的作用。 膳食DHA供应对激活和失活的功能影响 的光转导级联和突触效率的阶段， 光感受器双极结将在一个 随机试验 这些数据将提供对假设的第一次检验 神经膜脂肪酸组成的变化导致 在人类婴儿中的传导和神经传递。 4. 为了评估人类婴儿在体内和体内合成DHA的能力， 体外 基于PI最近的发现，体内延长/去饱和 婴儿体内必需脂肪酸（EFA）的含量有限，他计划评估 胎儿生长、胎龄和饮食对体内EFA的影响 转换. 体内研究将由体外研究补充 胎儿视网膜组织中LCP生物合成的时间函数， 培养、胎龄和脂肪酸底物。 来自体内的数据 体外研究将有助于确定内源性LCP生物合成 常规和特殊婴儿的容量和最佳脂质组成 公式。

DESCRIPTION: Most infant formulas provide ample alpha-linolenic acid (LNA) but formula fed infants are at risk for docosahexaenoic acid (DHA) deficiency due to their limited ability to metabolize this long-chain polyunsaturated fatty acid (LCP) from LNA during the first months of life. Formula-fed infants have abnormal fatty acid composition of red blood cells, retina and brain when compared with breast-fed infants, who obtain pre-formed DHA via human milk. Formula-fed infants whose diets lack both LNA and DHA exhibit less sensitive rod electroretinographic (ERG) function, poorer cortical visual evoked potential (VEP) acuity, poorer preferential-looking (PL) acuity, and lower scores on Fagan and Bayley tests. A specific need for dietary DHA in preterm and term infants is the focus of studies during the current grant period and the PI interim results support the essentiality of DHA for optimal maturation of visual function. 1. To delineate the role of DHA in supporting optimal maturation of cortical function. VEP and especially PL acuity have been widely used as indices of general maturation of the cortex or central nervous system; the motivation for these studies has been the quantification of subtle differences related to LCP composition of neural membranes. The PI proposes a series of studies to more directly evaluate cortical function via random dot stereoacuity and tests of cognitive function administered at 39 weeks, 4 years and 9 years of age. These data, coupled with VEP and PL acuity data, will also be used to examine the validity of the hypothesis that VEP and PL acuity provide indices of cortical maturation through analyses of concurrent and predictive validity for cognitive performance. 2. To evaluate the need for dietary supplementation following early weaning. Based on our data which support the essentiality of DHA in the term diet, we will address the question of whether DHA is essential in the post-weaning diet. Common practice in the US is a short 6-8 week period of breast-feeding; yet preliminary evidence suggests that a dietary supply of DHA is essential for at least 17 weeks. This study will be the first test of the essentiality of DHA in the post-weaning diet in the context of a randomized trial. 3. To evaluate the functional role of DHA in the neural retinal membranes of human infants. While there have been a number of studies on the role of DHA in neural membranes in vertebrates, little is known about the role of DHA in the neural membranes of the human infant. The functional effects of dietary DHA supply on activation and inactivation phases of the phototransduction cascade and the synaptic efficiency of the photo-receptor-bipolar junction will be evaluated in the context of a randomized trial. These data will provide the first test of the hypothesis that changes in neural membrane fatty acid composition lead to altered transduction and neurotransmission in the human infant. 4. To assess the capacity of human infants to synthesize DHA in vivo and in vitro. Based on the PI recent finding that in vivo elongation/desaturation of essential fatty acids (EFAs) in infants is limited, he plans to evaluate the impact of fetal growth, gestational age and diet on in vivo EFA conversion. in vivo studies will be complemented by in vitro investigations of LCP biosynthesis in fetal retinal tissue as a function of time in culture, gestational age and fatty acid substrate. Data from the in vivo and in vitro studies will assist in defining endogenous LCP biosynthetic capacity and optimal lipid composition for routine and specialty infant formulas.