Phillips I D, Simonetta G, Owens J A, Robinson J S, Clarke I J, McMillen I C
Department of Physiology, University of Adelaide, Australia.
Pediatr Res. 1996 Dec;40(6):861-6. doi: 10.1203/00006450-199612000-00014.
We have experimentally restricted placental growth in the sheep to investigate the impact of reduced substrate delivery on fetal pituitary proopiomelanocortin (POMC) mRNA levels and on circulating ACTH 1-39, immunoreactive ACTH, and cortisol concentrations during late gestation. Endometrial caruncles were removed in nine ewes before mating to reduce the number of placentomes formed [placental restriction group (PR)]. Fetal arterial PO2 and O2 saturation were reduced in the PR group (2.0 +/- 0.1 kPa and 42.8 +/- 1.1%, n = 9) when compared with control fetuses (3.1 +/- 0.1 kPa and 66.4 +/- 0.9%, n = 10). The ratio of anterior pituitary POMC mRNA:18 S ribosomal RNA was also lower (p < 0.05) in the PR group (0.49 +/- 0.05) when compared with the control group (0.80 +/- 0.12) after 140 d of gestation. In contrast, plasma concentrations of ACTH 1-39 and immunoreactive ACTH were similar in the PR and control groups throughout late gestation. Plasma ACTH 1-39 concentrations increased (p < 0.006) between 128 and 134 d of gestation, in both the PR (122-128 d: 2.70 +/- 0.34 pmol/L: 134-141 d; 7.07 +/- 1.57 pmol/L) and control (122-128 d; 3.36 +/- 0.56 pmol/L: 134-141 d; 10.78 +/- 2.88 pmol/L) groups. Combined adrenal weight was higher (p < 0.005) in the PR group (130 +/- 10 mg/kg) compared with controls (80 +/- 1 mg/kg) at 140 d of gestation, and plasma cortisol concentrations were also higher (p < 0.02) in PR than control fetuses between 127 and 141 d of gestation. These changes imply that the fetal hypothalamopituitary-adrenal axis is operating at a new central set point in the growth-restricted fetus.
我们通过实验限制绵羊胎盘生长，以研究妊娠晚期底物供应减少对胎儿垂体阿黑皮素原（POMC）mRNA水平以及循环中促肾上腺皮质激素（ACTH）1 - 39、免疫反应性ACTH和皮质醇浓度的影响。在9只母羊交配前切除子宫内膜肉阜，以减少胎盘叶的数量[胎盘受限组（PR）]。与对照胎儿（3.1±0.1 kPa和66.4±0.9%，n = 10）相比，PR组胎儿动脉血氧分压（PO2）和氧饱和度降低（2.0±0.1 kPa和42.8±1.1%，n = 9）。妊娠140 d后，与对照组（0.80±0.12）相比，PR组垂体前叶POMC mRNA与18 S核糖体RNA的比值也较低（p < 0.05）（0.49±0.05）。相反，在整个妊娠晚期，PR组和对照组血浆中ACTH 1 - 39和免疫反应性ACTH的浓度相似。在妊娠128至134 d期间，PR组（122 - 128 d：2.70±0.34 pmol/L；134 - 141 d：7.07±1.57 pmol/L）和对照组（122 - 128 d：3.36±0.56 pmol/L；134 - 141 d：10.78±2.88 pmol/L）的血浆ACTH 1 - 39浓度均升高（p < 0.006）。在妊娠140 d时，PR组（130±10 mg/kg）的肾上腺联合重量高于对照组（80±1 mg/kg）（p < 0.005），并且在妊娠127至141 d期间，PR组胎儿的血浆皮质醇浓度也高于对照组（p < 0.02）。这些变化表明，生长受限胎儿的胎儿下丘脑 - 垂体 - 肾上腺轴在一个新的中枢设定点上运作。
