Fetal control of maternal prolactin production and bioactivity in utero

Seminal plasma enhances and accelerates progesterone-induced decidualisation of human endometrial stromal cells

In preparation for embryo implantation, endometrial stromal cells (ESC) undergo differentiation, termed decidualisation. Enhancing endometrial decidualisation may overcome reduced endometrial receptivity, a major limiting factor in natural and assisted reproduction. To determine whether seminal plasma (SP) influences decidualisation, primary human ESC were treated with progesterone (P4, 50 ng mL(-1)) in the presence or absence of dialysed SP (0.5%) for 24 h or for up to 27 days to investigate immediate early effects or the effects of prolonged exposure, respectively. Combined SP and P4 treatment induced ESC morphological differentiation. Relative to control, P4 alone, and SP alone combined treatment with SP and P4 for 27 days significantly upregulated mRNA levels of the decidua-specific markers prolactin (PRL) and insulin-like growth factor binding protein 1 (IGFBP1). Consistently, PRL protein secretion was significantly increased over the course of 27 days combined SP and P4 treatment relative to control, P4 alone and SP alone. Likewise, IGFBP1 secretion was significantly greater relative to control and P4 alone over the course of 27 days. Thus, SP enhances and accelerates P4-mediated decidualisation of human ESC and may enhance endometrial receptivity.

The secretion of insulin-like growth factor I, prolactin and insulin-like growth factor binding protein 1 by the decidua as predictors of human fetal growth

To determine if in vitro secretion of the decidual peptides insulin-like growth factor I (IGF-I), prolactin or insulin-like growth factor binding protein 1 (IGFBP-1) correlates with infant birthweight in uncomplicated, term human pregnancies, decidua from 45 pregnancies with normally distributed birthweights was cultured in defined medium for 24 h. IGF-I, prolactin and IGFBP-1 concentrations in the culture medium were measured by radioimmunoassay. Neither infant birthweight nor a normalized measure of infant birthweight (birthweight z-score) correlated with the quantity of IGF-I, prolactin or IGFBP-1 secreted by the decidua from that pregnancy. There were no differences in any of the peptide hormones assayed when the pregnancies were grouped by infant sex. IGF-I and prolactin secretion by individual decidual samples correlated positively. IGF-I and IGFBP-1 secretion also correlated positively in individual samples. A previously identified correlation between decidual IGF-I secretion and infant birthweight among a group of normal and growth restricted (IUGR) pregnancies was not confirmed in the current study. These data indicate that the decrease in decidual IGF-I and prolactin secretion seen in IUGR pregnancies is not the hormone profile of the low birthweight end of a normal population, but a distinct endocrine profile.

Comparisons of glycosylated and nonglycosylated amniotic fluid prolactins in normal second- and third-trimester pregnancies

Prolactins in glycosylated and nonglycosylated form were isolated from 218 second- and third-trimester amniotic fluid samples by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electrotransferred to nitrocellulose paper, and probed with anti-human prolactin serum and protein A labeled with iodine 125. The glycosylated and nonglycosylated prolactin bands were exposed by autoradiography. The bands were analyzed by densitometry, and the ratio of glycosylated to total (glycosylated + nonglycosylated) prolactin was calculated (glycosylated/total ratio) and compared with matched prolactin radioimmunoassay measurements. Both radioimmunoassay-measured and nonglycosylated prolactin decreased from the second to the third trimester whereas glycosylated prolactin concentrations remained unchanged. Concomitantly, glycosylated/total prolactin ratios increased significantly (p less than 0.001). The correlation of radioimmunoassay-measured prolactin was closer to nonglycosylated prolactin (r2 = 0.32, p = 0.00001) than to glycosylated prolactin (r2 = 0.02, p = 0.06). We suggest that the proportion of amniotic fluid glycosylated prolactin increases with length of gestation and that glycosylation of prolactin is inversely related to total prolactin secretion. Furthermore, prolactin's immunoreactivity correlated more closely to the nonglycosylated-prolactin variant, suggesting that radioimmunoassay of prolactin poorly recognizes the glycosylated prolactin form.

Prolactin and related peptides in pregnancy

This brief review has attempted to portray the complex involvement of prolactin in pregnancy. Pituitary prolactin production and lactotroph proliferation are markedly affected by oestrogens and pregnancy. Enlargement of pre-existing prolactinomas may occur during pregnancy induced with dopamine agonist drugs, and this can be a major clinical problem with larger tumours. Prolactin is produced by late luteal and decidualized endometrium as well as by the pituitary gland, but much less is known about its secretory regulation or its function. The family of prolactin-related protein hormones is rapidly expanding with the recognition of placental lactogens, variant growth hormone, proliferin, decidual luteotropin, and at least two further prolactin-related peptides in rodents. This complex system of related but distinct protein hormones, with different temporal patterns of production during gestation, suggests an important physiological role, but it remains to be seen to what extent they are involved in placental function itself, maternal metabolism or fetal growth.

Influences of maternal smoking and fetal sex on maternal serum oestriol, prolactin, hCG, and hPI levels

A total of 222 pregnant women had repeated hormone assays between 20 weeks and delivery; 86 of the women were smokers. The maternal hormone balance appeared to be affected by smoking. Smoking affected maternal serum levels of hPL and hCG in pregnancies with a female fetus whereas maternal serum concentrations of oestriol and prolactin were affected in pregnancies with a male fetus. Significantly higher hCG levels were found in mothers who smoked and had a girl than in those who smoked and had a boy. On the basis of our results we feel that smoking mainly affects the placenta.