Placental growth hormone is not suppressed by oral glucose loading in normal human pregnancy

Relationship between elevated serum level of placental growth factor and status of gestational diabetes mellitus

Objective: As only limited and confusing evidence about serum placental growth factor (PlGF) level in gestational diabetes mellitus (GDM) exist in the known literature, the aim of this study was to evaluate the association of maternal serum PlGF level with GDM status.Methods: The pregnant women attending the Obstetrics Outpatient Unit of Hitit University Hospital were screened at 24 and 28 weeks of gestation for GDM according to the suggestions of the American College of Obstetricians and Gynecologists (ACOG). Concisely, all of the low-risk pregnant women were evaluated with a 50 g glucose challenge test (GCT). Women with serum glucose ≥140 mg/dL at 1 h after GCT were subjected to a 100 g oral glucose tolerance test (OGTT). According to the criteria of Carpenter and Coustan, the GDM diagnosis was confirmed. Consequently, a total of 158 pregnant women eligible for inclusion criteria were categorized into two main groups; 76 of the GDM group, 82 of the control group. The demographic characteristic and biochemical parameters of the study population including age, body mass index (BMI), gestational age were recorded at the second trimester. The assays for glucose, insulin, and PlGF were carried out.Results: The mean maternal age of control and GDM groups were 27.9 and 30.5 years, respectively. The parameters such as age, BMI, and gestational age were statistically similar in both groups (p>.05, for all). As expected, serum insulin level and homeostasis model assessment-insulin resistance (HOMA-IR) value were significantly elevated in women with GDM (p<.001, for both). Moreover, maternal PlGF concentration was found to be higher in the GDM group compared to the control group (p=.029). Pearson's correlation analysis of PlGF with other study parameters revealed that there was a negative moderate and significant correlation in only control group (r= -0.416, p<.05). However, this correlation was not detected in the GDM group (r = 0.099, p>.05). None of the variables including maternal age, BMI, insulin, and HOMA-IR showed significant correlations in GDM and control groups.Conclusion: Our findings revealed that maternal serum PlGF level is increased in pregnant women complicated with GDM. Early identification of pregnant women who subsequently will pose GDM risk could improve the pregnancy outcomes.

Discovery, Knowledge, and Action-Diabetes in Pregnancy Across the Translational Spectrum: The 2016 Norbert Freinkel Award Lecture

The Norbert Freinkel Award is given in memory of Norbert Freinkel, a dedicated and insightful investigator and gifted writer, to honor a researcher who has made outstanding contributions, including scientific publications and presentations, to the understanding and treatment of diabetes in pregnancy. H. David McIntyre, MD, FRACP, Director of Obstetric Medicine at Mater Health Services and Head of the Mater Clinical Unit at The University of Queensland in Brisbane, Australia, received the prestigious award at the American Diabetes Association's 76th Scientific Sessions, 10-14 June 2016, in New Orleans, LA. He presented the Norbert Freinkel Award Lecture, "Discovery, Knowledge, and Action-Diabetes in Pregnancy Across the Translational Spectrum," on Saturday, 11 June 2016.

Placental growth factor as a new marker for predicting abnormal glucose challenge test results

BACKGROUND

To differentiate placental growth factor (PlGF) levels in pregnancies with normal and abnormal glucose challenge test (GCT) results.

METHODS

A total of 94 pregnant women underwent a 50 -g GCT as part of our routine antenatal screening protocol from September 2011 to January 2012. The patients were divided into three groups: (i) normal GCT, (ii) abnormal GCT and (iii) gestational diabetes mellitus (GDM) based on the screening results for gestational diabetes. The main outcome measure of the study was the relationship between PlGF and GCT results in non-diabetic pregnancies. The Kolmogorov-Smirnov test was used to check the normality of the variables' distributions. The Kruskal-Wallis and analysis of variance tests (Tukey's test) were used to analyze the qualitative parameters.

RESULTS

There were 53 (56.4%), 22 (23.4%) and 19 (20.2%) patients in the normal GCT, abnormal GCT and GDM groups, respectively. The PlGF level in the abnormal GCT group was 518 ± 307.6 pg/mL, which was the highest level in the study population, and there was a statistically significant difference compared with the other groups (p = 0.006). There were no statistically significant differences with respect to fetal birth weight among the three groups in our study.

CONCLUSION

PlGF can be used as a laboratory marker to predict which patients will have abnormal GCT results.

On the function of placental corticotropin-releasing hormone: a role in maternal-fetal conflicts over blood glucose concentrations

Throughout the second and third trimesters, the human placenta (and the placenta in other anthropoid primates) produces substantial quantities of corticotropin-releasing hormone (placental CRH), most of which is secreted into the maternal bloodstream. During pregnancy, CRH concentrations rise over 1000-fold. The advantages that led selection to favour placental CRH production and secretion are not yet fully understood. Placental CRH stimulates the production of maternal adrenocorticotropin hormone (ACTH) and cortisol, leading to substantial increases in maternal serum cortisol levels during the third trimester. These effects are puzzling in light of widespread theory that cortisol has harmful effects on the fetus. The maternal hypothalamic-pituitary-adrenal (HPA) axis becomes less sensitive to cortisol during pregnancy, purportedly to protect the fetus from cortisol exposure. Researchers, then, have often looked for beneficial effects of placental CRH that involve receptors outside the HPA system, such as the uterine myometrium (e.g. the placental clock hypothesis). An alternative view is proposed here: the beneficial effect of placental CRH to the fetus lies in the fact that it does stimulate the production of cortisol, which, in turn, leads to greater concentrations of glucose in the maternal bloodstream available for fetal consumption. In this view, maternal HPA insensitivity to placental CRH likely reflects counter-adaptation, as the optimal rate of cortisol production for the fetus exceeds that for the mother. Evidence pertaining to this proposal is reviewed.

Pregnancy and acromegaly: a review

To review the literature regarding the diagnosis and management of acromegaly during pregnancy. A systematic literature search was performed using MEDLINE including hand-searching reference lists from original articles. The diagnosis of acromegaly during pregnancy is made difficult due to the physiologic changes in pituitary GH secretion and IGF-1 production resulting from placental GH secretion and the inability of commercial assays to discriminate between pituitary and placental GH. Most patients with acromegaly during pregnancy do not have an increase in tumor size, metabolic complications are uncommon, and neonatal outcome is largely unaffected. IGF-1 levels tend to be stable in such patients possibly due to the high estrogen levels causing GH resistance. Dopamine agonists, somatostatin analogues, and a GH receptor antagonist have been reported to be safe during pregnancy. Patients with visual field defects should be considered for surgery, but in most cases this can be safely postponed until after delivery. Overall, pregnancy in acromegaly is uneventful and newborns unaffected. Dopamine agonists and somatostatin analogues have not been associated with major adverse effects to the fetus; however, more data are needed to validate their safety.

Maternal and fetal placental growth hormone and IGF axis in type 1 diabetic pregnancy

AIM

Placental growth hormone (PGH) is a major growth hormone in pregnancy and acts with Insulin Like Growth Factor I (IGF-I) and Insulin Like Growth Hormone Binding Protein 3 (IGFBP3). The aim of this study was to investigate PGH, IGF-I and IGFBP3 in non-diabetic (ND) compared to Type 1 Diabetic (T1DM) pregnancies.

METHODS

This is a prospective study. Maternal samples were obtained from 25 ND and 25 T1DM mothers at 36 weeks gestation. Cord blood was obtained after delivery. PGH, IGF-I and IGFBP3 were measured using ELISA.

RESULTS

There was no difference in delivery type, gender of infants or birth weight between groups. In T1DM, maternal PGH significantly correlated with ultrasound estimated fetal weight (r = 0.4, p = 0.02), birth weight (r = 0.51, p<0.05) and birth weight centile (r = 0.41, p = 0.03) PGH did not correlate with HbA1c. Maternal IGF-I was lower in T1DM (p = 0.03). Maternal and fetal serum IGFBP3 was higher in T1DM. Maternal third trimester T1DM serum had a significant band at 16 kD on western blot, which was not present in ND.

CONCLUSION

Maternal T1DM PGH correlated with both antenatal fetal weight and birth weight, suggesting a significant role for PGH in growth in diabetic pregnancy. IGFBP3 is significantly increased in maternal and fetal serum in T1DM pregnancies compared to ND controls, which was explained by increased proteolysis in maternal but not fetal serum. These results suggest that the normal PGH-IGF-I-IGFBP3 axis in pregnancy is abnormal in T1DM pregnancies, which are at higher risk of macrosomia.

Regulation of placental growth hormone secretion in a human trophoblast model--the effects of hormones and adipokines

Placental growth hormone (PGH) is secreted from the human placental syncytiotrophoblast into the maternal circulation. PGH levels in pregnant women correlate with the birth weight of their offspring. We hypothesized that metabolic regulators may alter PGH secretion. BeWo cells as human trophoblast models were treated for 24, 48, and 72 h with insulin, insulin-like growth factor (IGF)-1, cortisol, ghrelin, leptin and visfatin. Cyclic-adenosinmonophosphate treatment served as positive control. PGH concentrations in culture media were measured. Insulin reduced (p < 0.008; analysis of variance) PGH secretion from BeWo cells after 72 h. No effect was found when treating cells with IGF-1. Cortisol reduced PGH secretion after 48 h (p < 0.00118; analysis of variance) and 72 h (p < 0.015). Leptin and ghrelin both suppressed (p < 0.027 and p < 0.017, paired t test) whereas visfatin increased (p < 0.014, paired t test) PGH secretion at 72 h. Cyclic adenosinmonophosphate increased (p < 0.003) PGH secretion at 72 h. Our results indicate that in vitro PGH secretion by BeWo cells is regulated by hormonal factors and adipokines. We speculate on the existence of a maternal-placental regulatory loop, in which elevated insulin and leptin levels might down-regulate PGH secretion.

Aspects of placental growth hormone physiology

Placental growth hormone (PGH) has been known for 20 years. Nevertheless, its physiology is far from understood. In this review, basal aspects of PGH physiology are summarised and put in relation to the highly homologous pituitary growth hormone (GH). During normal pregnancy, PGH progressively replaces GH and reach maximum serum concentrations in the third trimester. A close relationship to insulin-like growth factor (IGF)-I and -II levels is observed. Furthermore, PGH levels are positively associated to fetal growth. The potential importance of growth hormone receptors and binding protein for PGH effects is discussed. Finally, the review outlines current knowledge of PGH in pathological pregnancies.

Growth hormone binding protein and maternal body mass index in relation to placental growth hormone and insulin requirements during pregnancy in type 1 diabetic women

In pregnancy, the growth hormone axis is shifted from pituitary growth hormone (GH) to placental growth hormone (PGH). Their common binding protein, GH binding protein (GHBP), displays peak serum levels at mid-gestation in normal individuals. In the non-pregnant state, diabetes is known to be associated with elevated levels of GH and decreased levels of insulin-like growth factors (IGFs) and GHBP. Diabetes in pregnancy may therefore as well be associated with disturbances in the growth hormone axis. In the present study, we aimed at investigating the impact of GHBP and maternal body mass index (BMI) on levels of PGH, thereby enabling estimation of any association between free PGH and weight adjusted insulin requirements. In 51 type 1 diabetic women, blood samples were collected in gestational week 10+, 16+, 22+, 28+ and 34+, and analysed for their serum content of GHBP, PGH, and GH. Serum GHBP increased from the first weeks of pregnancy to median 2.07 nmol/l (range 1.17-4.26) in week 22+, then declined to median 1.29 nmol/l (range 0.77-2.35) in week 34+ (ANOVA P < 0.001). Serum PGH levels were highest in week 34+ at median 21.3 microg/l (range 5.1-165.4) (P < 0.001), whereas a steady decrease in GH values was observed throughout pregnancy to a median 0.17 microg/l (range 0-5.53). The fraction of calculated free PGH to total PGH increased from mid-gestation onwards to 55.2% (37.0-87.1) in week 34+ at a median level of free PGH of 10.4 microg/l (range 1.9-144.0) (P < 0.001). Similarly, the molar ratio of total PGH to GHBP increased to a maximum of 0.68 (0.12-6.62) in week 34+. As in normal pregnancies, the correlation between BMI and GHBP was lost in late pregnancy. The newborns birth weight z-score correlated with total PGH and derivatives here-of in week 34+. Neither total nor weight adjusted insulin requirements correlated to total PGH, calculated free PGH, nor GHBP. In conclusion, PGH and GHBP display a similar course during pregnancy in type 1 diabetic women as described in normal women. The well-known association between GHBP and BMI was lost in late pregnancy. Calculated levels of free PGH were positively associated to fetal growth, but not to maternal insulin requirements.