Rosner W, Beers P C, Awan T, Khan M S
J Clin Endocrinol Metab. 1976 Jun;42(6):1064-73. doi: 10.1210/jcem-42-6-1064.
We have studied the concentration and properties of a protein which binds cortisol in human milk in samples obtained from women during the first 100 days after delivery. A filter disk assay was developed both for the measurement of plasma corticosteroid-binding globulin (CBG) and for the cortisol-binding protein in milk. The concentration of CBG in milk, expressed as its capacity to bind cortisol, is highest on the day of delivery, ca, 0.80 mug/dl, falls over the next 10 days to ca. 0.25 mug/dl, and remains at that level thereafter. If the concentration of CBG is expressed relative to the concentration of serum albumin in milk, it increases from day 1 to day 3 and then remains constant. A detailed comparison of CBG derived from milk and plasma showed that the two proteins co-migrated on Sephadex, sucrose gradient ultracentrifugation, and polyacrylamide gel electrophoresis. The two proteins had the same affinity for cotrisol, progesterone, 17-OH-progesterone, and dexamethasone. Furthermore, the binding activity of CBG in milk was neutralized with anti-CBG antibodies raised against CBG isolated from plasma. Unlike CBG, the concentration of cortisol in milk, 0.8-3.5 mug/dl, showed no systematic variation as a function of the postpartum day on which the sample was obtained.
我们研究了从产后100天内的女性获取的母乳样本中一种结合皮质醇的蛋白质的浓度和特性。我们开发了一种滤纸片测定法，用于测量血浆皮质类固醇结合球蛋白（CBG）以及母乳中的皮质醇结合蛋白。母乳中CBG的浓度，以其结合皮质醇的能力表示，在分娩当天最高，约为0.80微克/分升，在接下来的10天内降至约0.25微克/分升，此后维持在该水平。如果CBG的浓度相对于母乳中血清白蛋白的浓度表示，它从第1天到第3天增加，然后保持恒定。对母乳和血浆来源的CBG进行的详细比较表明，这两种蛋白质在葡聚糖凝胶、蔗糖密度梯度超速离心和聚丙烯酰胺凝胶电泳中共同迁移。这两种蛋白质对皮质醇、孕酮、17-羟孕酮和地塞米松具有相同的亲和力。此外，母乳中CBG的结合活性被针对从血浆中分离出的CBG产生的抗CBG抗体中和。与CBG不同，母乳中皮质醇的浓度为0.8 - 3.5微克/分升，并未显示出作为获取样本的产后天数的函数的系统性变化。
