Hill D J
MRC Group in Fetal and Neonatal Health and Development, Lawson Research Institute, London, Ont., Canada.
Horm Res. 1992;38 Suppl 1:28-34. doi: 10.1159/000182567.
The role of growth hormone (GH) and the related placental lactogens in implantation and subsequent embryonic and fetal development is an enigma. Firstly, these peptides are abundant in both the fetal and maternal circulation. The variant growth hormone (hGH-V) is expressed by the placental syncytiotrophoblast and is released into the maternal circulation. It is not detectable in fetal blood. Fetal pituitary (GH) is abundant but is not a primary stimulus to human fetal musculoskeletal growth, since hypopituitary newborn infants have near-normal birth size. However, pituitary hGH has been shown to stimulate pancreatic islet growth and insulin release in vitro, and to be a mitogen for fetal hepatocytes obtained in late first trimester. This selectivity of action is confirmed by the immunohistochemical localization of hGH receptor in the human fetal kidney, endocrine pancreas, liver, skin and brain during the first and second trimester, and their absence from the musculoskeletal system, gut and lung. High-affinity human placental lactogen (hPL) receptors are abundant in animal and human fetal tissues, and hPL can attain concentrations of 10 nM in the human fetal circulation. In vitro data strongly suggest anabolic and mitogenic actions for PL on fetal tissues, including amino acid transport, hepatic glycogenesis, protein synthesis, and stimulation of insulin-like growth factor and insulin release. The PL axis in the fetus is influenced by maternal nutrition. Despite these findings, definitive evidence is still lacking that PL contributes to fetal growth and development in utero.
生长激素（GH）及相关胎盘催乳素在着床以及随后的胚胎和胎儿发育过程中的作用仍是一个谜。首先，这些肽在胎儿和母体循环中都很丰富。变异生长激素（hGH-V）由胎盘合体滋养层细胞表达并释放到母体循环中，在胎儿血液中无法检测到。胎儿垂体中的生长激素（GH）含量丰富，但并非人类胎儿肌肉骨骼生长的主要刺激因素，因为垂体功能减退的新生儿出生时大小接近正常。然而，垂体hGH已被证明在体外可刺激胰岛生长和胰岛素释放，并且是孕早期晚期获取的胎儿肝细胞的有丝分裂原。这种作用的选择性通过孕早期和孕中期人胎儿肾脏、内分泌胰腺、肝脏、皮肤和大脑中hGH受体的免疫组化定位得到证实，而在肌肉骨骼系统、肠道和肺中则不存在。高亲和力的人胎盘催乳素（hPL）受体在动物和人类胎儿组织中大量存在，并且hPL在人类胎儿循环中的浓度可达10 nM。体外数据强烈表明PL对胎儿组织具有合成代谢和有丝分裂作用，包括氨基酸转运、肝糖原生成、蛋白质合成以及刺激胰岛素样生长因子和胰岛素释放。胎儿体内的PL轴受母体营养的影响。尽管有这些发现，但仍缺乏确凿证据表明PL有助于子宫内胎儿的生长发育。
