EFFECTS OF DIFFERENT BREAST PUMPING PROTOCOLS ON ALPHA LACTALBUMIN MRNA CONCE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 假设 假设：H1：使用吸乳器完全排空乳房引起的催乳素和催产素的生理性增加将比频繁的乳房排空小脉冲更能增加α-乳清蛋白的mRNA。 具体目标： 该方案将试图确定与排空乳房有关的收集时间是否会影响乳脂球(MFG)中的mRNA含量，并确定这种mRNA浓度的变化与血浆催乳素和催产素浓度的关系。 背景和意义： 母乳是新生儿的理想食物，母乳喂养的婴儿胃肠炎、中耳炎和一些过敏情况的发生率较低(母乳喂养工作组)。美国儿科学会建议婴儿在出生后6个月内接受母乳喂养，部分母乳喂养最多1年(美国儿科学会政策)。许多女性在母乳喂养中苦苦挣扎，那些尝试母乳喂养的人中，只有不到25%的人成功地喂养了一个月以上。人们认为乳糖生产是人类乳汁生产的主要调节因素，因为它是牛奶中的主要渗透剂(Mephan，1987)。与牛奶蛋白质和脂肪相反，奶水中的乳糖浓度从母乳喂养开始到结束是恒定的，但具有物种特异性(Davies等1983)。在过去的几年里，我们已经使用稳定的葡萄糖同位素示踪剂证明，50%到60%的乳糖来自母亲的血糖，而母乳中高达40%到50%的乳糖来自乳腺上皮内乳糖的从头合成过程(Sunehag等人2002年，Sunehag等人2003年)。来自己酮形成的乳糖比例受禁食的影响，但不受重组人生长激素处理的影响，尽管重组人生长激素增加了30%的产奶量(Kaplan等人)。控制己酮发生和乳糖合成的机制(S)在人类中尚不清楚。母乳中的脂肪成分表现为乳脂球(MFG)(Patton等人1988年，Huston等人1990年)。由于MFG是由顶分泌机制产生的，每个MFG都被乳房顶端细胞膜包围，该细胞膜包裹着大的脂滴和新月形的乳房上皮细胞胞浆。我们相信，如果我们能够从底物、激素和分子基础上理解母乳产生的机制，我们可能会更好地对成功母乳喂养婴儿的女性数量产生积极影响。 初步研究/进度报告 我们最近已经证明，我们可以通过RT-PCR从人乳中的乳脂球中分离和定量一些信使核糖核酸，包括a-乳蛋白，它被认为是增加半乳糖基转移酶活性的关键辅助因素，半乳糖基转移酶是生产乳糖的关键酶(Stacey等人，1995)。我们希望这项技术的发展将使我们有机会在体内研究荷尔蒙对人类乳腺上皮细胞转录和翻译的调节作用。由于婴儿哺乳或使用吸奶器引起的乳头刺激会触发乳头-垂体反射，导致催产素和催乳素的分泌(Cos 1996)。在我们最初的研究中，我们观察到我们所获得的牛奶样本中a-乳清蛋白mRNA的显着变化，但这种浓度在注射重组生长激素的头2-3天内明显增加(未发表的数据)。我们认为，这些差异可能反映了这样一个事实，即我们对获取乳样的时间与最后一次母乳喂养的关系的潜在影响并不敏感。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. HYPOTHESIS Hypotheses: H1: Physiologic increases in prolactin and oxytocin induced by complete emptying of the breast using a breast pump will increase mRNA of alpha-lactalbumen more than frequent small pulses of breast emptying. SPECIFIC AIMS: This protocol will attempt to determine if timing of collection in relation to emptying the breast will affect the mRNA content in milk fat globules (MFG) and to determine the relationship of changes in this mRNA concentrations and the plasma concentrations of prolacting and oxytocin. BACKGROUND AND SIGNIFICANCE: Breast milk is the ideal food for newborn infants and infants who are breast fed have a lower incidence of gastroenteritis, otitis media and a number of allergic conditions (Work Group on Breastfeeding). The American Academy of Pediatrics recommends that infant be fed breast milk for the first 6 mondhs of life and partially fed breast milk for up to 1 year (American Academy of Pediatrics Policy). A number of women struggle with breast feeding and less than 25% of those who attempt it are successful for longer than 1 month. It is assumed that lactose production is a primary regulator of human milk production since it is the primary osmotic agent in milk (Mephan 1987). As opposed to milk proteins and fat, the lactose concentration in milk water is constant from the initiation of a breast-feeding until the end, but is species specific (Davies et al 1983). Over the past several years, we have demonstrated using stable isotope tracers of glucose that 50 to 60% of lactose is derived from maternal plasma glucose but that up to 40 to 50% of lactose in human milk is derived from a process of de novo synthesis of lactose within the mammary epithelium (Sunehag et al 2002, Sunehag et al 2003). The proportion of lactose derived from hexoneogenesis is affected by fasting but not rhGH treatment despite the fact that rhGH increased milk production by 30% (Kaplan et al). The mechanism(s) by which hexoneogenesis and lactose synthesis are controlled is not known in humans. The fat component in human milk appears as a milk fat globule (MFG) (Patton et al 1988, Huston et al 1990). Since MFG are produced by an apocrine mechanism, each is surrounded by mammary apical cell membrane which encloses a large lipid droplet and a crescent of mammary epithelial cell cytosol. We believe that if we are able to understand the mechanisms responsible for milk production from a substrate, hormone and molecular basis that we might be in a better position to positively impact the numbers of women who can successfully breast feed their infants. PRELIMINARY STUDIES/PROGRESS REPORT We have recently demonstrated that we can isolate and quantitate by RT-PCR a number of mRNA species from the milk fat globule in human milk, including a-lactalbumen which is thought to be a key co-factor increasing the activity of galactosyl transferase, a key enzyme in the production of lactose (Stacey et al 1995). The development of this technique we hope will permit us the opportunity to study in vivo regulation of hormonal regulation of transcription and translation of a number of potentially regularoty proteins in the mammary epithelial cell of the human breast. Nipple stimulation as a result of infant suckling or the use of a breast pump triggers a nipple-pituitary reflex resulting in the secretion of both oxytocin and prolactin (Cos 1996). From our initial studies we observed a significant variation of a-lactalbumin mRNA in the milk samples that we have obtained but that this concentration clearly increase over the first 2-3 days of rhGH administration (unpublished data). We believe that these variations may reflect the fact that we were not sensitive to the potential impace of the timing of the obtaining of milk samples in relationship to the last breast feeding.