Salminen-Lappalainen K, Laatikainen T
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Clin Chim Acta. 1990 Dec 31;195(1-2):57-66. doi: 10.1016/0009-8981(90)90194-w.
Placenta secretes corticotropin-releasing hormone (CRH) into the maternal and fetal circulation, but a CRH binding protein in plasma may decrease its biological activity. Using a charcoal adsorption method we found that 92% of added 125I-Tyr-CRH was bound to a binding protein in the nonpregnant plasma, 72% in the plasma at term pregnancy, 90% in umbilical cord plasma, 82% in the amniotic fluid in the second and 25% in the third trimester. CRH added to plasma inhibited the binding of 125I-Tyr-CRH over the concentration range of 0.1-8.8 nmol/l in plasma and of 0.1-2.2 nmol/l in amniotic fluid. There was a significant negative correlation (R = -0.80) between the binding capacity of the CRH-binding protein and CRH concentration in maternal plasma. Plasma or amniotic fluid was incubated with 125I-Tyr-CRH and subjected to gel filtration on Sephadex G-50. The bound radioactivity was eluted at the region of Mr 25-40 kDa and the unbound radioactivity at the location of synthetic CRH. Bound and unbound CRH concentrations were determined using charcoal adsorption method and gel filtration on Sephadex G-50 in ten maternal plasma samples at the third trimester of pregnancy. Following mean percentages were found to be bound: charcoal method 61.9 +/- 6.80% (SE) and gel filtration 62.8 +/- 6.33%. We conclude that the bulk of CRH is bound to a binding protein in maternal and fetoplacental circulation, whereas at term pregnancy the role of the binding is small in amniotic fluid.
胎盘将促肾上腺皮质激素释放激素（CRH）分泌到母体和胎儿循环中，但血浆中的CRH结合蛋白可能会降低其生物活性。我们采用活性炭吸附法发现，添加的125I-酪氨酸-CRH中有92%与未孕血浆中的一种结合蛋白结合，足月妊娠血浆中为72%，脐带血浆中为90%，孕中期羊水为82%，孕晚期为25%。添加到血浆中的CRH在血浆浓度范围为0.1 - 8.8 nmol/l以及羊水浓度范围为0.1 - 2.2 nmol/l时，可抑制125I-酪氨酸-CRH的结合。CRH结合蛋白的结合能力与母体血浆中CRH浓度之间存在显著负相关（R = -0.80）。将血浆或羊水与125I-酪氨酸-CRH一起孵育，然后在Sephadex G-50上进行凝胶过滤。结合的放射性物质在Mr 25 - 40 kDa区域洗脱，未结合的放射性物质在合成CRH的位置洗脱。在妊娠晚期的10份母体血浆样本中，使用活性炭吸附法和Sephadex G-50凝胶过滤法测定结合和未结合的CRH浓度。发现结合的平均百分比为：活性炭法61.9 +/- 6.80%（标准误），凝胶过滤法62.8 +/- 6.33%。我们得出结论，大部分CRH在母体和胎儿-胎盘循环中与一种结合蛋白结合，而在足月妊娠时，该结合在羊水中的作用较小。
