Ellis L, Picciano M F
Department of Nutrition, Pennsylvania State University, University Park 16802.
Endocr Regul. 1993 Dec;27(4):181-92.
This study was undertaken to determine if PRL variants differing in structural characteristics as well as biological activity and immunoreactivity are present in human milk and to assess whether the physiological state of the mammary gland (premature initiation of lactation, progression of lactation) influences the forms or activity of human milk-borne PRL. Human milk samples were collected in early (day 1-5) or mature lactation (1-4 months) from women delivering term (T) or preterm (PT) infants. Milk was fractionated on Sephadex G-100, Concanavalin A-Sepharose, or Phosphogel to estimate molecular weight (MW), degree of glycosylated PRL(G), and degree of phosphorylated (P) PRL, respectively. Prolactin-like bioactivity (B) was measured by the PRL-dependent proliferation of the Nb-2 lymphoma cell and PRL-like immunoreactivity (I) by radioimmunoassay (RIA) using NIDDK reagents. Milk obtained from mothers of T infants contained significantly greater B than I-PRL at each stage of lactation (early: B = 132 +/- 13.9 P.E./ml, I = 83.43 +/- 12 P.E./ml, mature: B = 41.74 +/- 8.9 P.E./ml, I = 27.19 +/- 5.5 P.E./ml; P < 0.01-0.001). PRL-like bioactivity was greatest in early milk produced by mothers of T infants and declined as lactation progressed. No differences in B or I-PRL were evident for milk collected from mothers of preterm infants at any stage of lactation. In early lactation the PRL-like bioactivity of milk collected from mothers of T infants was significantly greater than in unfractionated milk collected from mothers of PT infants (P < 0.05). The number of PRL variants present in milk was characteristic of the stage of lactation and gestation (T early > PT early; T early > T mature). Early milk from mothers of T infants contained an average of 5 bioactive PRL variants, early milk from mothers of PT infants an average of 4 bioactive variants, and mature milk from mothers of T infants an average of 3 bioactive variants. The distribution of molecular weights associated with PRL variants in milk infranatant was variable among subjects within a specific stage of lactation/gestation. However, the representative range of molecular weights of PRL variants identified in milk sample was similar between groups (T early: < 8, 16, 20, 24, 25-28, 32, 42, > 66; PT early: 16, 20, 23, 25-28, 32, > 66; T mature: 20, 25-28, 32, 35, > 66).(ABSTRACT TRUNCATED AT 400 WORDS)
本研究旨在确定人乳中是否存在结构特征、生物活性及免疫反应性不同的催乳素（PRL）变体，并评估乳腺的生理状态（泌乳过早开始、泌乳进程）是否会影响人乳中PRL的形式或活性。从足月（T）或早产（PT）婴儿母亲处收集早期（第1 - 5天）或成熟泌乳期（1 - 4个月）的人乳样本。将乳汁分别在葡聚糖G - 100、伴刀豆球蛋白A - 琼脂糖或磷酸凝胶上进行分级分离，以分别估计分子量（MW）、糖基化PRL（G）程度和磷酸化（P）PRL程度。通过Nb - 2淋巴瘤细胞的PRL依赖性增殖来测量催乳素样生物活性（B），并使用美国国立糖尿病、消化和肾脏疾病研究所（NIDDK）试剂通过放射免疫测定法（RIA）测量催乳素样免疫反应性（I）。在泌乳的每个阶段，从足月婴儿母亲处获得的乳汁中所含的B显著高于I - PRL（早期：B = 132 ± 13.9标准误/ml，I = 83.43 ± 12标准误/ml；成熟：B = 41.74 ± 8.9标准误/ml，I = 27.19 ± 5.5标准误/ml；P < 0.01 - 0.001）。足月婴儿母亲早期乳汁中的催乳素样生物活性最高，并随着泌乳进程而下降。在泌乳的任何阶段，从早产婴儿母亲处收集的乳汁中B或I - PRL均无明显差异。在早期泌乳期，从足月婴儿母亲处收集的乳汁中催乳素样生物活性显著高于从未足月婴儿母亲处收集的未分级乳汁（P < 0.05）。乳汁中存在的PRL变体数量具有泌乳阶段和妊娠的特征（足月早期 > 早产早期；足月早期 > 足月成熟）。足月婴儿母亲的早期乳汁平均含有5种生物活性PRL变体，早产婴儿母亲的早期乳汁平均含有4种生物活性变体，足月婴儿母亲的成熟乳汁平均含有3种生物活性变体。在泌乳/妊娠的特定阶段，各受试者乳汁上清液中与PRL变体相关的分子量分布存在差异。然而，各组间在乳汁样本中鉴定出的PRL变体分子量的代表性范围相似（足月早期：< 8、16、20、24、25 - 28、32、42、> 66；早产早期：16、20、23、25 - 28、32、> 66；足月成熟：20、25 - 28、32、35、> 66）。（摘要截短于400字）
