Cirelli N, Lebrun P, Gueuning C, Delogne-Desnoeck J, Vanbellinghen A M, Graff G, Meuris S
Research Laboratory on Reproduction, Université Libre de Bruxelles, B-1070 Brussels, Belgium.
Hum Reprod. 2001 Mar;16(3):441-8. doi: 10.1093/humrep/16.3.441.
This study investigates whether albumin, a major plasma protein in direct contact with the trophoblast in vivo, can modulate human chorionic gonadotrophin (HCG) and human placental lactogen (HPL) releases from placental explants. Incubating explants with a near physiological, i.e. 5%, concentration of human or bovine albumin during 30 min increased HCG and HPL release by at least 150%. This albumin effect was not mediated by any difference in hormone adsorption onto glass surfaces. In contrast to the sustained stimulation of hormone releases elicited by the addition of 10 mmol/l extracellular calcium, the albumin-mediated secretory responses were transient. However, the albumin- and calcium-stimulatory effects were abolished at 4 degrees C, depressed by 0.36 mmol/l cycloheximide or 1 mmol/l colchicine and potentiated by 40 micromol/l cytochalasin B. Moreover, the stimulatory effect of albumin on the hormone releases was not modified in the absence of Ca(2+) or in the presence of 1 or 10 mmol/l Ca(2+) in the extracellular milieu. These data suggest that albumin is involved, at physiological concentration, in the secretion of HCG and HPL by human placenta. The cellular mechanism(s) underlying the albumin-mediated secretory responses may be partly different from those involved during the calcium-mediated stimulation.
本研究调查了白蛋白（一种在体内与滋养层直接接触的主要血浆蛋白）是否能够调节人绒毛膜促性腺激素（HCG）和人胎盘催乳素（HPL）从胎盘外植体中的释放。将外植体与接近生理浓度（即5%）的人或牛白蛋白一起孵育30分钟，可使HCG和HPL的释放增加至少150%。这种白蛋白效应并非由激素在玻璃表面的吸附差异介导。与添加10 mmol/l细胞外钙所引发的激素释放的持续刺激相反，白蛋白介导的分泌反应是短暂的。然而，白蛋白和钙的刺激作用在4℃时被消除，被0.36 mmol/l环己酰亚胺或1 mmol/l秋水仙碱抑制，并被40 μmol/l细胞松弛素B增强。此外，在细胞外环境中不存在Ca(2+)或存在1或10 mmol/l Ca(2+)的情况下，白蛋白对激素释放的刺激作用未被改变。这些数据表明，生理浓度的白蛋白参与了人胎盘分泌HCG和HPL的过程。白蛋白介导的分泌反应背后的细胞机制可能与钙介导的刺激过程中所涉及的机制部分不同。
