Placental hormone

Xu et al. [76] have showed that human embryonic stem cells by treatment with bone morphogenetic protein-4 can be driven to differentiate into tro-phoblasts which have the ability to syncytialize and form confluent mono-layers. The differentiated cells express a number of trophoblast markers and secrete placental hormones and thus may provide an alternative placental model. Under the culture conditions used, however, the cells propagated poorly. 

It stimulates placental progesterone synthesis and increases the secretion of placental hormones. 

Human pituitary GH (somatotropin) is a 191-amino-acid peptide with two sulfhydryl bridges. Its structure closely resembles that of prolactin and the placental hormone human chorionic somatomammotropin. Pituitary-derived GH is no longer used (see below). Animal GH is not completely homologous to human GH and is ineffective in humans. 

The main actions of prolactin in mammals are concerned with the mammary gland (see below). Lactogenic and mammogenic actions are also shown by several other hormones, including the placental lactogens found in man and many other mammalian species [5-7]. The physiological role of these placental hormones has not been fully established, but it does seem likely that their biochemical mode of action will prove to be similar in some respects to that of prolactin. Their structural relationships to GH and prolactin are discussed in Chapter 13. 

Fukata J (1989) Two-site immunoradiometric assay for adreno-corticotrophin a cautionary study about the reactivity to its precursor molecules. Endocrinol Jpn 36 155-61 Ganong WF (1974) ACTH and the regulation of adrenocorticol secretion. N Engl J Med 290 1006 Genazzani AR (1975) Immunoreactive ACTH and cortisol plasma levels during pregnancy. Detection and partial purification of corticotrophin-like placental hormone the human chorionic corticotrophin (HCC). din Endocrinol (Oxf) 4 1-14... 

GH is a single-chain polypeptide with a molecular mass of 21,500 Da that contains 191 amino acids and two intramolecular disulfide bridges. It is structurally similar to PRL and to the placental hormone chorionic somatomammotropin (hCS, placental lactogen), with which it has overlapping biological effects. Many consider GH, PRL, and hCS to have descended from a common single primordial peptide. 

The placenta produces several protein and steroid hormones (Figure 54-1). The major protein hormones are CG and placental lactogen (PL). The steroids include progesterone, estradiol, estriol, and estrone. The placenta secretes most of its products into the maternal circulation only small amounts reach the fetal circulation. Close proximity of the maternal blood vessels to the site of placental hormone production may explain some of this preferential accumulation of hormones in the maternal blood circulation. Generally, hormone production by the placenta increases in proportion to the increase in placental mass. Therefore concentrations of hormones derived from the placenta, such as PL, increase in maternal peripheral blood as the placenta increases in size CG, which peaks at the end of the first trimester, is an exception. 

One of the most important placental hormones is CG. CG stimulates the ovary to produce progesterone which, in turn, prevents menstruation thereby protecting the pregnancy. The chemistry, biochemistry, and methods for CG are discussed in the section on laboratory tests later m this chapter. 

Cunningham FG, MacDonald PC, Gant NF. The placental hormones. In WEEams obstetrics. 18th ed. Norwalk, Conn Appleton Lange, 1989 67-85. 

One important measure of the effects of maternal stress during pregnancy involves infant temperament. Maternal stress during pregnancy predicts cognitive performance deficits and fearfulness in infancy.55 Measures of temperament and behavioral reactivity in the first few years of postnatal life show the influence of prenatal stress and maternal-placental hormones.56... 

Successful perfusion can be ensured by the production of placental hormones, use of oxygen and glucose, and transfer of antipyrine (Ala-Kokko et at., 2000). However,... 

Cultured trophoblasts Grow in monolayer, express corticotrophin-relea.sing factor Placental hormone secretion Petraglia et al. (1989)... 

Malignant gestational Hamster xenograft F12-15 Secretes placental hormones, hCG,... 

Sonographic features of the uterus in neonate, prepubertal, and pubertal girls. Under the influence of maternal and placental hormones the neonatal uterus is more prominent and measures 3.5 cm in length and 1.4 cm in thickness, with a definable endometrial stripe (Fig. 7.9). 

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