Cortisol-cortisone ratios in small for gestational age (SGA) children without postnatal catch-up growth

Influence of Low Protein Diet-Induced Fetal Growth Restriction on the Neuroplacental Corticosterone Axis in the Rat

Objectives: Placental steroid metabolism is linked to the fetal hypothalamus-pituitary-adrenal axis. Intrauterine growth restriction (IUGR) might alter this cross-talk and lead to maternal stress, in turn contributing to the pathogenesis of anxiety-related disorders of the offspring, which might be mediated by fetal overexposure to, or a reduced local enzymatic protection against maternal glucocorticoids. So far, direct evidence of altered levels of circulating/local glucocorticoids is scarce. Liquid chromatography tandem-mass spectrometry (LC-MS/MS) allows quantitative endocrine assessment of blood and tissue. Using a rat model of maternal protein restriction (low protein [LP] vs. normal protein [NP]) to induce IUGR, we analyzed fetal and maternal steroid levels via LC-MS/MS along with the local expression of 11beta-hydroxysteroid-dehydrogenase (Hsd11b). Methods: Pregnant Wistar dams were fed a low protein (8%, LP; IUGR) or an isocaloric normal protein diet (17%, NP; controls). At E18.5, the expression of Hsd11b1 and 2 was determined by RT-PCR in fetal placenta and brain. Steroid profiling of maternal and fetal whole blood, fetal brain, and placenta was performed via LC-MS/MS. Results: In animals with LP-induced reduced body (p < 0.001) and placental weights (p < 0.05) we did not observe any difference in the expressional Hsd11b1/2-ratio in brain or placenta. Moreover, LP diet did not alter corticosterone (Cort) or 11-dehydrocorticosterone (DH-Cort) levels in dams, while fetal whole blood levels of Cort were significantly lower in the LP group (p < 0.001) and concomitantly in LP brain (p = 0.003) and LP placenta (p = 0.002). Maternal and fetal progesterone levels (whole blood and tissue) were not influenced by LP diet. Conclusion: Various rat models of intrauterine stress show profound alterations in placental Hsd11b2 gatekeeper function and fetal overexposure to corticosterone. In contrast, LP diet in our model induced IUGR without altering maternal steroid levels or placental enzymatic glucocorticoid barrier function. In fact, IUGR offspring showed significantly reduced levels of circulating and local corticosterone. Thus, our LP model might not represent a genuine model of intrauterine stress. Hypothetically, the observed changes might reflect a fetal attempt to maintain anabolic conditions in the light of protein restriction to sustain regular brain development. This may contribute to fetal origins of later neurodevelopmental sequelae.

Born from pre-eclamptic pregnancies predisposes infants to altered cortisol metabolism in the first postnatal year

Pre-eclampsia leads to disturbed fetal organ development, including metabolic syndrome, attributed to altered pituitary-adrenal feedback loop. We measured cortisol metabolites in infants born from pre-eclamptic and normotensive women and hypothesised that glucocorticoid exposure would be exaggerated in the former. Twenty-four hour urine was collected from infants at months 3 and 12. Cortisol metabolites and apparent enzyme activities were analysed by gas chromatography-mass spectrometry. From 3 to 12 months, excretion of THS, THF and pregnandiol had risen in both groups; THF also rose in the pre-eclamptic group. No difference was observed with respect to timing of the visit or to hypertensive status for THE or total F metabolites (P>0.05). All apparent enzymes activities, except 17α-hydroxylase, were lower in infants at 12 compared to 3 months in the normotensive group. In the pre-eclamptic group, only 11β-HSD activities were lower at 12 months.17α-hydroxylase and 11β-HSD activities of tetrahydro metabolites were higher in the pre-eclamptic group at 3 months (P<0.05). 11β-hydroxylase activity increased in the pre-eclamptic group at 12 months. Cortisol excretion, determined by increased 11β-hydroxylase, compensates for high 11β-HSD-dependent cortisol degradation at 3 months and at 12 months counterbalances the reduced cortisol substrate availability in infants born from pre-eclamptic mothers.

Detection of expressional changes induced by intrauterine growth restriction in the developing rat mammary gland via exploratory pathways analysis

Background

Intrauterine growth restriction (IUGR) is thought to lead to fetal programming that in turn contributes to developmental changes of many organs postnatally. There is evidence that IUGR is a risk factor for the development of metabolic and cardiovascular disease later in life. A higher incidence of breast cancer was also observed after IUGR. This could be due to changes in mammary gland developmental pathways. We sought to characterise IUGR-induced alterations of the complex pathways of mammary development at the level of the transcriptome in a rat model of IUGR, using pathways analysis bioinformatics.

Methodology/Principal Findings

We analysed the mammary glands of Wistar rats with IUGR induced by maternal low protein (LP) diet at the beginning (d21) and the end (d28) of pubertal ductal morphogenesis. Mammary glands of the LP group were smaller in size at d28, however did not show morphologic changes. We identified multiple differentially expressed genes in the mammary gland using Agilent SurePrint arrays at d21 and d28. In silico analysis was carried out using Ingenuity Pathways Analysis. In mammary gland tissue of LP rats at d21 of life a prominent upregulation of WT1 and CDKN1A (p21) expression was observed. Differentially regulated genes were associated with the extracellular regulated kinase (ERK)-1/-2 pathway. Western Blot analysis showed reduced levels of phosphorylated ERK-1/-2 in the mammary glands of the LP group at d21. To identify possible changes in circulating steroid levels, serum LC-Tandem mass-spectrometry was performed. LP rats showed higher serum progesterone levels and an increased corticosterone/dehydrocorticosterone-ratio at d28.

Conclusions/Significance

Our data obtained from gene array analysis support the hypothesis that IUGR influences pubertal development of the rat mammary gland. We identified prominent differential regulation of genes and pathways for factors regulating cell cycle and growth. Moreover, we detected new pathways which appear to be programmed by IUGR.

Expression of neuropeptide Y, omentin and visfatin in visceral and subcutaneous adipose tissues in humans: relation to endocrine and clinical parameters

OBJECTIVE

We aimed at exploring the expression of neuropeptide Y (NPY), omentin and visfatin in adipose tissues of adults along with clinical parameters and hormones.

METHODS

We included 168 adult patients (31 surgical obese patients and 31 surgical controls, 76 non-surgical obese patients, 30 non-surgical controls). We measured plasma NPY (by radioimmunoassay), cortisol (with an electrochemiluminescence immunoassay) and urinary cortisol metabolites (by gas chromatography/mass spectrometry). Expression of NPY, omentin and visfatin in subcutaneous and visceral adipose tissue specimens of the surgical patients was quantified using real-time PCR.

RESULTS

NPY was detectable in adipose tissue specimens and, like plasma NPY concentrations, comparable between groups. Omentin gene expression was higher in visceral than in subcutaneous adipose tissues (p < 0.0001). Visfatin expression was lower in the subcutaneous tissue of obese patients compared with controls (p < 0.05). Cortisol was lower in obese adults compared with controls (136.5 +/- 74.1 vs. 162.2 +/- 56.1 ng/ml; p < 0.05), cortisol metabolites were comparable between groups.

CONCLUSION

In our obese adults, plasma NPY levels and the glucocorticoid measures were not elevated. Even though the expression of NPY, omentin and visfatin was comparable between obese individuals and controls, we have to consider differences in the total production rate of adipose tissue-derived factors.

Placental 11beta-HSD2 gene expression at birth is inversely correlated with growth velocity in the first year of life after intrauterine growth restriction

Intrauterine growth restriction (IUGR) is associated with an increased risk for short stature and diseases in adulthood thought to be inflicted by fetal programming. We hypothesized that placental endocrine systems involved in perinatal growth might also play a role in postnatal growth after IUGR. In a prospective controlled multicenter study, placental gene expression of IGF-binding protein-1 (IGFBP-1), leptin and 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) were measured in 14 IUGR infants and 15 children born appropriate for gestational age (AGA) proven by serial ultrasound examinations. Postnatally, IUGR infants experienced a significantly higher growth velocity than AGA neonates (at 1 y: p = 0.001). Gene expression of 11beta-HSD2 at birth correlated positively with birth length (r = 0.55, p = 0.04) and inversely with growth velocity in the first year of life (r = -0.69, p = 0.01) in the IUGR, but not in the AGA group. There was no correlation between gene expression of placental IGFBP-1, leptin and birth weight, length and growth velocity during the first year of life. AGA infants showed significantly higher concentrations of cortisone in venous cord blood after birth (p = 0.02) as a surrogate of a higher 11beta-HSD2 activity in the fetoplacental unit. In conclusion, placental 11beta-HSD2 gene expression might predict postnatal growth in IUGR.

Steroid measurement with LC-MS/MS in pediatric endocrinology

The liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an increasingly common tool in the clinical laboratory. Established applications include routine assays for detecting inborn errors of metabolism and for monitoring therapeutic drugs and steroids. Steroid profiling is a very effective method for distinguishing almost all steroid related disorders. It allows accurate diagnosis and is very useful in many clinical situations. Most methods for the determination of steroid hormones are based on immunoassays, which are rapid and easy to perform. However, the reliability of steroid immunoassays has been shown to be doubtful because of the lack of specificity and of matrix effects. Immunological methods, especially direct assays, often overestimate true steroid values. This is of particular importance in the newborn period and in early infancy. Problems with steroid immunoassays have further been reported for female patients or when analysing different media, e.g. saliva. Patient follow-up over time or between laboratories, as well as longitudinal studies are extremely difficult. In contrast to immunoassays, which allow the measurement of only a single steroid at a time, LC-MS/MS has the advantage that a wide spectrum of steroid hormones can be measured simultaneously. The applicability for clinical samples and problems in pediatric endocrinology will be discussed.

Catch-up growth in body mass index is associated neither with reduced insulin sensitivity nor with altered lipid profile in children born small for gestational age

OBJECTIVE

Low birth weight is a risk factor for coronary heart disease. Persons who have coronary events as adults tend to have been small at birth and thin at 2 yr of age, after which they tended to increase their body mass index (BMI). Our aim was to determine whether BMI gain is associated to alterations in insulin sensitivity and/or lipid profile in children born small for gestational age (SGA).

DESIGN

Retrospective case-control study.

METHODS

We studied 78 children (mean age 7.8+/-2.5 yr): 26 SGA children with catch-up growth in BMI (CGB-SGA) (BMI= 10th to 75th centile), 26 SGA without catch-up growth (NCGB-SGA) (BMI<10th centile), and 26 appropriate for gestational age (AGA) control children (BMI: 10th to 75th centile). For each CGB-SGA child, we selected an NCGB-SGA and an AGA child of the same gender, age (within 1 yr), and pubertal status. SGA children were also subdivided into 2 groups according to post-natal catch-up growth in height (CGH).

RESULTS

Glucose was significantly lower in NCGBSGA than AGA group (p=0.02). No significant differences in fasting insulin, fasting glucose/insulin ratio, homeostasis model assessment, quantitative insulin-sensitivity check index, and lipid profile were found among the 3 groups. HDL-cholesterol proved significantly reduced in SGA children with post-natal CGH (p=0.02).

CONCLUSIONS

Our findings do not support the hypothesis of early alterations in insulin sensitivity and lipid metabolism in CGB-SGA subjects during childhood provided that BMI remains within the normal range. Finally, the finding of reduced HDL-cholesterol levels in CGH-SGA children suggests detrimental metabolic effects of the height gain.