Klemcke H G
USDA, ARS, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska 68933-0166, USA.
Biol Reprod. 1995 Dec;53(6):1293-301. doi: 10.1095/biolreprod53.6.1293.
An experiment was conducted in pigs to determine the source of fetal cortisol at 50 (n = 5) or 100 days (n = 4) of gestation (term = 114 days). Equilibrium concentrations of tritiated cortisol were achieved, and all hormonal measures were made at 110, 130, 140, and 150 min in anesthetized pigs. Maternal plasma cortisol did not differ (p = 0.48) between 50 (70.2 +/- 7.4 ng/ml; mean +/- SEM) and 100 days (62.4 +/- 5.8 ng/ml). Conversely, fetal cortisol increased (p = 0.048) between 50 (8.5 +/- 2.5 ng/ml) and 100 days (24.2 +/- 4.2 ng/ml), and, at each gestational age, values were lower (p = 0.001) than those in maternal plasma. Plasma cortisone (15.1 +/- 2.3 ng/ml) did not change with gestational age (p = 0.42) in either compartment (maternal or fetal), nor did it differ between compartments (p = 0.08). Maternal cortisol accounted for 22.8 +/- 2.0% of fetal cortisol at 50 days of gestation, and this contribution decreased (p < 0.001) to 5.87 +/- 0.8% at 100 days. At both ages, maternal cortisol accounted for almost 50% of fetal cortisone. Metabolism of maternal cortisol by the entire uterofetoplacental unit was 8.4 +/- 1.7% at 50 days and 7.5 +/- 2.4% at 100 days (p = 0.76). The maternal metabolic clearance rate of cortisol increased 44% (p = 0.003) between 50 and 100 days (1.49 +/- 0.4 vs. 2.15 +/- 0.2 L/min). Hence at these gestational ages, the fetus--presumably the fetal adrenal--is the primary source of fetal plasma cortisol. The major contribution of maternal cortisol to fetal cortisone strongly suggests the presence of porcine placental 11 beta-hydroxysteroid dehydrogenase activity. Further, factors constituting the placental "barrier" that metabolize maternal cortisol to cortisone and other products may be major regulators of porcine fetal plasma cortisol and cortisone.
在猪身上进行了一项实验，以确定妊娠50天（n = 5）或100天（n = 4）时（足月为114天）胎儿皮质醇的来源。实现了氚化皮质醇的平衡浓度，并在麻醉的猪身上于110、130、140和150分钟时进行了所有激素测量。妊娠50天（70.2±7.4 ng/ml；平均值±标准误）和100天时母体血浆皮质醇无差异（p = 0.48）（62.4±5.8 ng/ml）。相反，胎儿皮质醇在50天（8.5±2.5 ng/ml）和100天时增加（p = 0.048）（24.2±4.2 ng/ml），并且在每个胎龄时，其值均低于母体血浆中的值（p = 0.001）。血浆可的松（15.1±2.3 ng/ml）在任何一个隔室（母体或胎儿）中均不随胎龄变化（p = 0.42），隔室之间也无差异（p = 0.08）。妊娠50天时母体皮质醇占胎儿皮质醇的22.8±2.0%，到100天时这一贡献下降（p < 0.001）至5.87±0.8%。在两个年龄段，母体皮质醇均占胎儿可的松的近50%。整个子宫 - 胎盘 - 胎儿单位对母体皮质醇的代谢在50天时为8.4±1.7%，在100天时为7.5±2.4%（p = 0.76）。母体皮质醇的代谢清除率在50天至100天之间增加了44%（p = 0.003）（1.49±0.4对2.15±0.2 L/min）。因此，在这些胎龄时，胎儿 - 大概是胎儿肾上腺 - 是胎儿血浆皮质醇的主要来源。母体皮质醇对胎儿可的松的主要贡献强烈表明猪胎盘存在11β - 羟类固醇脱氢酶活性。此外，构成胎盘“屏障”将母体皮质醇代谢为可的松和其他产物的因素可能是猪胎儿血浆皮质醇和可的松的主要调节因子。
