| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Disciplines of Physiology (S.M.M., D.N.T., C.L.C., I.C.M.) and Biochemistry (J.P.S.), School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5005; South Australian Research and Development Institute (S.K.W., D.O.K.), Turretfield Research Centre, Rosedale 5350; and Sansom Institute (S.M.M., D.N.T., S.G., I.C.M.), School of Pharmacy and Medical Sciences, University of South Australia, Adelaide 5000, South Australia, Australia
Address all correspondence and requests for reprints to: Professor I. C. McMillen, Head, Early Origins of Adult Health Research Group, The Sansom Research Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia. E-mail: caroline.mcmillen{at}unisa.edu.au.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
It has been proposed that because twin fetuses compete for placental substrate supply in late gestation that a programmed delay in the prepartum increase in plasma cortisol in twin fetal sheep would protect against preterm delivery (2). The differential impact of periconceptional undernutrition (PCUN) on pituitary-adrenal activation in twin fetal sheep suggests that maternal, embryonic, or placental responses to undernutrition may program the early trajectory of fetal adrenal growth and development. Studies in human pregnancies with more than two fetuses have found that after the number of embryos is reduced to two in the first trimester, the birth weights of the remaining twins were significantly reduced compared with the birth weights in the nonreduced twin pregnancies, indicating that the fetal growth trajectory may be set early in pregnancy (6). In sheep, we have reported that the growth trajectory of the fetus and placenta are also set early in pregnancy and that PCUN has a differential effect on fetal and placental growth in singleton and twin pregnancies before d 55 gestation (7).
During early gestation (d 
40–60), the fetal adrenal gland of the sheep undergoes hyperplastic growth and a phase of increased steroidogenic activity (8, 9, 10, 11). Furthermore at this gestational age, there is high expression of the key steroidogenic enzyme, cytochrome P450 17-hydroxylase (CYP17), in the fetal sheep adrenal when compared with later (d 100–120) in gestation. Intraadrenal IGFs have also been implicated in the regulation of adrenal growth and steroidogenesis in the fetal sheep (12). IGF-II, a paternally imprinted gene (13), is maximally expressed in a range of fetal tissues including the adrenal during early gestation where it is present in adrenocortical steroidogenic cells (12, 14). Although it is known in a range of tissues that the level of expression of the maternally expressed clearance receptor, IGF-II receptor (IGF-IIR), can regulate the bioavailability of IGF-II within fetal tissues (15, 16, 17, 18, 19), there have been no studies that have investigated the level of expression of either the IGF-IR or IGF-IIR in the fetal adrenal during early pregnancy. It is also not known whether fetal adrenal growth and the adrenal expression of steroidogenic enzymes, IGFs, IGF-IR, and IGF-IIR, are different in twin compared with singleton fetuses at this early stage in gestation.
Although PCUN has a differential impact on the prepartum activation of the pituitary-adrenal axis, it is unknown whether there are changes in adrenal growth or functional development from early in pregnancy, i.e. during the period of maximal adrenal growth and development at approximately d 55 in twin and singleton pregnancies. The fetus is normally protected from the high levels of maternal cortisol by the placental enzyme 11ß-hydroxysteroid dehydrogenase-2 (11ß-HSD2), which is a unidirectional nicotinamide adenine dinucleotide-dependent enzyme that catalyzes the conversion of the biologically active cortisol to the inert cortisone (20). There is evidence that exposure of the sheep to maternal undernutrition for a period extending beyond the preimplantation period up to the first 30 d after conception (21) or from early to mid gestation (between 28 and 78 d gestation) (22) results in a decrease in placental 11ß-HSD2 expression or activity. There are no studies, however, that have determined whether undernutrition during the periconceptional period alone (i.e. a period before conception and extending to blastocyst formation) results in changes in placental 11ß-HSD2 expression that persist in early pregnancy. Furthermore, there have been no studies of the impact of PCUN on the placental expression of 11ß-HSD1, which is a reduced nicotinamide adenine dinucleotide phosphate-dependent isoform that acts to convert cortisone to cortisol. We have therefore determined whether PCUN alters maternal cortisol concentrations, placental 11ß-HSD1 and -2 mRNA or protein expression, fetal adrenal weight, the mRNA levels of IGF-I and -II and their receptors, and the expression of CYP17 in the fetal adrenal during the phase of maximal hyperplastic growth of the adrenal at d 55 gestation and whether there is a differential effect of PCUN on the fetal adrenal from early in pregnancy.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Forty-five South Australian Merino ewes were used in this study, and the feeding and breeding protocols were as previously reported (7). Briefly, ewes were moved into an enclosed shed and housed in pens 2 wk before the start of the feeding regime. All ewes were weighed and a body condition score assessed employing a 1–5 scale with 0.5 intervals by an experienced assessor (23, 24). Using this scale, a body condition score of 1 represents an extremely emaciated animal and a body condition score of 5 represents an extremely obese animal. During this 2-wk period, ewes were acclimatized to a pelleted diet containing cereal hay, lucerne hay, barley, oats, almond shells, lupins, oat bran, lime, and molasses (Johnsons & Sons Pty. Ltd., Kapunda, South Australia, Australia). The pellets provided 9.5 MJ/kg metabolizable energy and 120 g/kg crude protein and contained 90.6% dry matter. All ewes received 100% of nutritional requirements (7.6 MJ/d for the maintenance of a 64-kg nonpregnant ewe) as defined by the Agricultural and Food Research Council in 1993 (25). At the end of this acclimatization period, ewes were randomly assigned to one of two feeding regimes, a control regime (n = 24), in which ewes received 100% of nutritional requirements or a periconceptional restricted regime (PCUN, n = 21), in which ewes received 70% of the control allowance. All of the dietary components were reduced by an equal amount in the restricted diet. Ewes were maintained on these respective diets for at least 45 d before mating. Control ewes were maintained on the control diet for 62 ± 5 d, and the ewes in the PCUN group were maintained on the 70% diet for 55 ± 2 d before conception. The starting weights were not different between ewes that were allocated to the control group (65.6 ± 1.2 kg) or the PCUN group (62.4 ± 1.3 kg).
Ewes were released in a group every evening at 1600 h with two intact rams of proven fertility that were fitted with harnesses and marker crayons. Ewes were individually penned the following morning at 0800 h, and the occurrence of mating was confirmed by the presence of a crayon mark on the ewe’s rump. The day of mating was defined as d 0. Ewes in the PCUN group were maintained on the 70% restricted diet for 7 d after conception. From d 7 of pregnancy, all ewes were fed a control diet (100% of requirements) until postmortem at d 53–56 pregnancy. Ewes were weighed and their body condition was assessed and scored approximately every 2 wk after commencing the feeding regime until postmortem at d 53–56 of pregnancy. Ewes in the PCUN group lost more weight (–4.52 ± 0.82 kg, P < 0.0001) than control ewes (0.54 ± 0.66 kg) between the start of the feeding regime and d 10 of pregnancy. Pregnancy was diagnosed and fetal number estimated by ultrasound at d 45 of pregnancy. The number of fetuses carried by each ewe was confirmed at postmortem, generating four treatment groups: control singleton pregnancies (n = 18), PCUN singleton pregnancies (n = 16), control twin pregnancies (n = 6), and PCUN twin pregnancies (n = 5).
Collection of tissues
Ewes were killed with an overdose of sodium pentobarbitone (Virbac Pty. Ltd., Peakhurst, New South Wales, Australia) between d 53 and 56 of pregnancy (term = 150 ± 3 ds gestation), and the uteroplacental unit was delivered by hysterotomy. Fetal organs, including the adrenals, were dissected from the fetus. Fetal adrenals were snap frozen immediately in liquid nitrogen and stored at –80 C. Fetal adrenals were weighed on a microbalance immediately before RNA extraction. The placenta was immediately dissected, and the placentomes were individually weighed and counted. Between two and four placentomes from each placenta were snap frozen immediately in liquid nitrogen and stored at –80 C for further analysis.
Maternal blood samples
Blood samples were collected from the jugular vein by venipuncture from all ewes on the 12th day after the start of the feeding regime (control, 50 ± 5 d before conception; PCUN, 43 ± 2 d before conception), on the 40th day after the start of the feeding regime (control, 22 ± 5 d before conception; PCUN, 19 ± 2 d before conception) and at postmortem between d 53 and 56 of pregnancy. Blood samples (10 ml) were collected into chilled heparinized tubes. All samples were centrifuged at 1500 x g for 10 min and plasma separated into aliquots and stored at –20 C for the measurement of nonesterified free fatty acids (FFA) and maternal plasma progesterone and cortisol.
FFA assay
As a measurement of maternal nutrient restriction, maternal plasma FFA concentrations were measured in all samples in one assay by an in vitro enzymatic colorimetric method (Wako Pure Chemicals Industries Ltd., Osaka, Japan). The sensitivity of the assay was 0.25 mEq/liter, and the intraassay coefficient of variation was less than 5%.
Progesterone RIA
Progesterone was measured in maternal plasma using a RIA (Diagnostic Systems Laboratories Inc., Webster, TX). The sensitivity of the assay was less than 0.3 ng/ml, and the cross-reactivity of the progesterone antiserum was less than 0.1% with cortisol, pregnenolone, and estradiol. All maternal samples were measured within the one assay, and the intraassay coefficient of variation was less than 5%.
Cortisol RIA
Cortisol was extracted from maternal plasma samples in duplicate using dichloromethane (26) and measured using an assay previously validated for use in sheep plasma (27). The efficiency of the recovery was more than 85%. Samples were then reconstituted in assay buffer (Tris hydrochloride, BSA, and sodium azide). Standards were serially diluted in assay buffer from a stock (1000 nmol/liter) solution (range, 0.78–100 nmol/liter). Anticortisol (100 µl; 1:15 dilution; Orion Diagnostica, Turku, Finland) was added followed by 125I-labeled cortisol (100 µl; Amersham Pharmacia Biotech, Little Chalfont, UK). Tubes were vortexed and incubated at 37 C for 1 h before the addition of goat antirabbit serum (initial dilution 1:30; 100 µl) and polyethylene glycol (1 ml, 20%; BDH Laboratory Supplies, Poole, UK). Tubes were vortexed before centrifugation at 3700 x g and 4 C for 30 min. The supernatant was aspirated and the precipitate counted on a 
-counter (Packard, Downers Grove, IL). The sensitivity of the assay was 0.2 nmol/liter. The intra- and interassay coefficients of variation were less than 15%.
RNA extraction and cDNA synthesis
RNA was isolated from frozen adrenal and placental tissue samples using Trizol reagent (Invitrogen, Groningen, The Netherlands) and purified using the RNeasy Mini Kit (QIAGEN, Basel, Switzerland). Genomic DNA contamination was minimized by treating each sample with DNase 1 (Ambion, Austin, TX), and RNA was quantified by spectrophotometric measurements at 260 and 280 nm. cDNA was synthesized from 5 µg RNA using Superscript III (Invitrogen, The Netherlands) by RT. Controls containing no RNA transcript or no superscript were used to test for DNA contamination.
Quantitative real-time RT-PCR (qRT-PCR)
The relative abundance of IGF-I, IGF-II, IGF-IR, IGF-IIR, and CYP17 mRNA transcripts in fetal adrenal tissue were measured by qRT-PCR using the SYBR Green system in an ABI Prism 7000 Sequence Detection System (Applied Biosystems, Foster City, CA). Each qRT-PCR well contained 5 µl SYBR Green Master Mix (Applied Biosystems), 1 µl each of forward and reverse primer (GeneWorks, Adelaide, South Australia, Australia) for the appropriate gene (Table 1
), water (2 µl), and 50 ng/µl cDNA (1 µl) to give a total volume of 10 µl. Controls for each primer set containing no cDNA were included on each plate. Three replicates of cDNA from each pair of fetal adrenal glands were performed for each gene on each plate, and each plate was repeated three times to ensure a consistent result. Amplification efficiencies were determined from the slope of a plot of Ct (defined as the threshold cycle with the lowest significant increase in fluorescence) against the log of the cDNA template concentration (ranging from 1–100 ng/µl). The abundance of each transcript relative to the abundance of the reference gene ribosomal protein P0 (RpP0) was calculated using Q-Gene analysis software (28).
|
Western blot analysis
Protein was extracted from frozen placental tissues. Briefly, approximately 50 mg tissue was homogenized in 500 µl homogenizing buffer (50 mM Tris-HCl, 150 mM NaCl, 1 mM NaV, 10 mM NaF, 0.6% Triton X-100) containing one Complete Mini Protease Inhibitor Cocktail Tablet (Roche Diagnostics, Penzberg, Germany). Homogenate was centrifuged at 1800 rpm for 30 min at 4 C. The supernatant was collected and protein concentration was determined by Bradford assay using bovine -globulin as the standard (Bio-Rad, Hercules, CA). Protein samples (40 µg) were separated by SDS-PAGE and transferred to a nitrocellulose membrane using standard protocol previously validated in this laboratory. Nitrocellulose membranes were immunoprobed for 11ß-HSD1 and -2 protein using rabbit antihuman 11ß-HSD1 and -2 antisera as primary antibodies (Cayman Chemical, Ann Arbor, MI). Briefly, blots were washed three times for 5 min each in Tris-buffered saline (TBS) and blocked for 1 h at room temperature with 5% wt/vol BSA in TBS with 0.1% Tween 20 (TBST) with gentle agitation. Primary antibodies were diluted 1:400 in 5% BSA-TBST and incubated overnight at 4 C with gentle agitation. Blots were then washed three times for 5 min each at room temperature in TBST and incubated with an alkaline phosphatase-conjugated donkey antirabbit IgG (Rockland Immunochemicals, Inc., Gilbertsville, PA) diluted 1:1000 in 5% BSA-TBST for 1 h at room temperature with gentle agitation. Blots were washed three times for 5 min each in TBST with gentle agitation. Immunoreactive proteins were detected by chemifluorescence (ECF substrate; Amersham, GE Healthcare, Little Chalfont, UK) as per the manufacturer’s specifications, and membranes were scanned using Typhoon scanner (Amersham). Single bands were identified with a migratory pattern consistent with the predicted protein size when compared with a protein ladder (Kaleidoscope Prestained Standards; Bio-Rad), and the intensity of this band was determined using ImageQuant software version 5.2 (Molecular Dynamics, Sunnyvale, CA).
Statistical analysis
Data are presented as the mean ± SEM. The effects of PCUN and fetal number on maternal FFA, progesterone, and cortisol concentrations; absolute and relative fetal adrenal weight and fetal adrenal expression of IGF-I, IGF-IR, IGF-II, IGF-IIR, and CYP17; and placental 11ß-HSD1 and -2 expression (mRNA and protein) were determined using a two-way ANOVA using the SPSS for Windows version 11.5 (SPSS Inc., Chicago, IL). When there was a significant effect of either fetal number or PCUN and there was no interaction between these main effects, data were pooled for presentation. Relationships between variables were assessed by linear regression using Sigma Plot 8.0 (SPSS), and partial correlation analyses were used where appropriate. A probability level of 5% (P < 0.05) was assumed to be significant.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
PCUN and maternal plasma progesterone and cortisol
Progesterone.
Plasma progesterone concentrations were marginally but significantly higher (P = 0.02; Table 2) in the PCUN compared with the control group in ewes that would go on to carry twin pregnancies. Maternal plasma progesterone concentrations were significantly higher, however, in ewes carrying twin fetuses at d 53–56 gestation and this occurred independently of the level of periconceptional nutrition (P < 0.0001; Table 2).
|
), plasma cortisol concentrations were lower in the PCUN group than in controls (11.1 ± 2.1 nmol/liter vs. 26.9 ± 6.6 nmol/liter, P < 0.04; Table 2) on d 40 of the feeding regime (Table 2). Plasma cortisol concentrations were not different, however, between the control and PCUN groups at d 53–56 pregnancy (13.3 ± 2.4 nmol/liter vs. 14.9 ± 3.4 nmol/liter, respectively; Table 2).
For twin pregnancies, on d 12 of the feeding regime, plasma cortisol concentrations were higher in the PCUN than control ewes (37.3 ± 10.6 nmol/liter vs. 7.7 ± 0.4 nmol/liter P < 0.02; Table 2), but there was no difference in plasma cortisol between the two feeding groups on either d 40 of feeding (15.6 ± 3.0 nmol/liter vs. 26.6 ± 7.4 nmol/liter, respectively; Table 2) or d 53–56 of pregnancy (18.8 ± 4.2 nmol/liter vs. 10.6 ± 2.4 nmol/liter, respectively; Table 2).
PCUN, fetal number, and placental 11ß-HSD1 and 11ß-HSD2 mRNA and protein expression
There was no effect of maternal nutrition during the periconceptional period on the relative expression of 11ß-HSD1 mRNA or 11ß-HSD1 protein expression in the placentae of either singleton or twin pregnancies (Table 3).
|
), and this was independent of the level of maternal nutrition during the periconceptional period. Although there was no specific effect of PCUN on placental expression of 11ß-HSD2 mRNA, 11ß-HSD2 protein expression was increased in the PCUN group in both singleton and twin pregnancies (P < 0.01; Table 3).
PCUN, fetal number, and fetal adrenal weight on d 53–56
There was no effect of PCUN on the weights of singleton and twin fetuses. The absolute and relative adrenal weights were each significantly lower (P < 0.0001), however, in twin compared with singleton fetuses in both the PCUN and control groups (Table 4). There was no effect of PCUN on either the absolute or relative fetal adrenal weight on d 53–56 in either singleton or twin fetuses (Table 4).
|
and 2). There was no effect of PCUN on adrenal expression of either IGF-I, IGF-IR, IGF-II, or IGF-IIR mRNA on d 53–56 of gestation in either singleton or twin fetuses.
|
|
Twins.
In contrast to control singleton fetuses, there was no relationship between adrenal weight and either adrenal IGF-II or IGF-IIR mRNA expression in control twins, but there was a significant relationship between relative adrenal weight (y) and adrenal IGF-I mRNA expression (x) (see Fig. 5A) in control twins that was not present in the PCUN group.
|
), independent of maternal nutritional during the periconceptional period.
|
) but not control twin or PCUN fetuses.
|
), which was not present in singleton fetuses. |
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Maternal progesterone and cortisol concentrations and placental 11ß-HSD2 mRNA expression in twin pregnancies
Although maternal progesterone concentrations were higher, as expected in twin pregnancies, there were no differences in circulating cortisol concentrations between singleton and twin pregnancies on d 53–56 of gestation. Interestingly, the expression of placental 11ß-HSD2 mRNA was higher in twin compared with singleton pregnancies. Although this might suggest that materno-fetal transfer of cortisol in these pregnancies may be lower, we note that there was no difference in placental 11ß-HSD2 protein expression between twin and singleton pregnancies. It does not appear, therefore, that the decreased adrenal growth and CYP17 expression in twin pregnancies, is a direct consequence of enhanced materno-fetal transfer of cortisol and increased negative feedback actions of maternal cortisol on the twin pituitary-adrenal axis.
Adrenal growth and IGFs and CYP17 expression in singleton and twin fetuses
In control singletons, there was an inverse rather than a positive correlation between relative adrenal weight and IGF-II expression. This relation was not significant, however, once the effects of IGF-IIR expression were controlled for in the analysis. Given the direct relationship between adrenal expression IGF-II and IGF-IIR, it seems likely that low adrenal IGF-IIR expression results in an increase in IGF-II bioavailability in the adrenal and enhanced adrenal growth. This is supported by the presence of an inverse relationship between adrenal CYP17 and IGF-IIR mRNA expression in the control singletons. IGF-II is colocalized to steroidogenic cells of the adrenal gland at this stage of gestation (12), and one possibility is that IGF-II acts to up-regulate adrenal CYP17 mRNA expression at approximately d 55 of gestation. Thus, in the control singleton fetus in early pregnancy, it appears that the clearance receptor IGF-IIR plays a key role in determining the bioavailability of IGF-II in the adrenal and that IGF-II may be an important determinant of early adrenal growth and steroidogenic activity.
In twins, however, there was an emergence of a positive relationship between adrenal weight and adrenal IGF-I rather than IGF-II expression. Thus, in twin fetuses, when adrenal IGF-II expression is lower than in the singleton, IGF-I may become the major determinant of adrenal growth. There was, however, a direct relationship between adrenal CYP17 and IGF-II mRNA expression in twin fetuses.
Thus, in summary, in control singletons, IGF-IIR expression may play an important role in the regulation of the intraadrenal bioavailability of IGF-II and thus in the regulation of adrenal growth and CYP17 mRNA expression during early pregnancy. In control twins, however, adrenal CYP17 and IGF-II expression are related, but adrenal growth appears to be predominantly related to IGF-I mRNA expression.
The lower adrenal IGF-I, IGF-II, and CYP17 mRNA expression clearly may contribute to a decrease in adrenal growth and function in twin fetuses in early gestation. Although it is intriguing to speculate that the early environment of the twin embryo may act through epigenetic mechanisms to down-regulate the expression of the imprinted genes, IGF-II and IGF-IIR, it is the case that the expression of the nonimprinted genes, IGF-I and IGF-IR, were also down-regulated in the adrenal of the twin fetus. Independent of the mechanisms involved, we have demonstrated that the growth trajectory of the fetal adrenal in the twin is different from that of the singleton sheep fetus from early in pregnancy and that therefore the delay in the prepartum activation of the pituitary-adrenal axis in the twin fetus is programmed early in pregnancy.
Impact of PCUN on placental and adrenal growth and development
Although there was no effect of PCUN on the mean level of placental 11ß-HSD1 or -2 mRNA expression, there was a significant increase in placental 11ß-HSD2 protein expression in PCUN but not control pregnancies. This is important in the context that an increase in the dehydrogenation of maternal cortisol to inactive cortisone could lead to less negative feedback on the developing HPA axis in PCUN pregnancies. Manipulation of maternal nutrition can result in altered expression and/or activity of placental 11ß-HSD2 in a range of species (30 , 31). Interestingly, periods of maternal undernutrition that extend beyond implantation and up to 30 d gestation (21) or between d 28–78 of gestation (22) result in a decrease in placental 11ß-HSD2 mRNA expression or activity, although these changes are not necessarily associated with changes in cord blood cortisol concentrations (21).
In ewes carrying singletons that were exposed to undernutrition during the periconceptional period, we found that there was a loss of the relationship between adrenal IGF-II mRNA expression and adrenal weight or between IGF-IIR and CYP17 mRNA expression. In ewes carrying twins, maternal undernutrition during the periconceptional period resulted in the loss of the relationships between adrenal growth and IGF-I expression and between adrenal CYP17 and IGF-II expression that were present in control twin fetuses. These data highlight that the regulation of adrenal growth and functional development is different in both singleton and twin fetal sheep after a period of PCUN and that the preconceptional period and first week after conception are critical windows within which exposure of the embryo to relatively subtle changes in maternal nutrition result in changes in neuroendocrine development. It remains to be determined whether the effects of maternal undernutrition extending beyond the preimplantation period to include early placental formation (4) are similar to those described above or include both a periconceptional and early gestational component.
Summary
In summary, the present study has demonstrated that fetal adrenal weight and CYP17 mRNA expression were each lower in twin compared with singleton fetuses. We hypothesize that the changes in fetal adrenal growth and steroidogenic enzyme expression are in part mediated by the lower levels of expression of adrenal IGF-II, IGF-IIR, IGF-I, and IGF-IR mRNA present in the twin fetus. In control singletons, it appears that IGF-IIR expression may be important in determining intraadrenal bioavailability of IGF-II and in the regulation of adrenal growth and CYP17 mRNA expression during early pregnancy. In control twins, however, although adrenal CYP17 and IGF-II expression are related, adrenal growth appears to be predominantly regulated by IGF-I. Independent of the mechanisms involved, the growth trajectory of the fetal adrenal in the twin is different to that of the singleton sheep fetus from early in pregnancy, and the delay in the prepartum activation of the pituitary-adrenal axis in the twin fetus may therefore be programmed from early in pregnancy. In addition, PCUN ablated the relationships between adrenal IGF mRNA expression and adrenal growth and CYP17 mRNA expression, which were present in the control singleton and twin fetuses. These findings highlight the importance of the interaction between the periconceptional environment and embryo number in setting the growth trajectories of the fetal adrenal during early pregnancy and suggest that the differences in the timing of the prepartum activation of the fetal adrenal present between singleton and twin fetuses, and after maternal undernutrition in the periconceptional period, have their origins in the environment of the embryo during the first week after conception.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
Disclosure Information: S.M.M., S.K.W., D.O.K., J.P.S., D.N.T., S.G., C.L.C., and I.C.M. have nothing to declare.
First Published Online December 28, 2006
Abbreviations: CYP17, Cytochrome P450 17-hydroxylase; FFA, free fatty acids; HPA, hypothalamo-pituitary-adrenal; 11ß-HSD2, 11ß-hydroxysteroid dehydrogenase-2; IGF-IIR, IGF-II receptor; PCUN, periconceptional undernutrition; TBS, Tris-buffered saline; TBST, TBS with 0.1% Tween 20.
Received June 8, 2006.
Accepted for publication December 19, 2006.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  J. A. Duffield, T. Vuocolo, R. Tellam, B. S. Yuen, B. S. Muhlhausler, and I. C. McMillen Placental restriction of fetal growth decreases IGF1 and leptin mRNA expression in the perirenal adipose tissue of late gestation fetal sheep Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2008; 294(5): R1413 - R1419. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. W. H. Rumball, M. H. Oliver, E. B. Thorstensen, A. L. Jaquiery, S. M. Husted, J. E. Harding, and F. H. Bloomfield Effects of Twinning and Periconceptional Undernutrition on Late-Gestation Hypothalamic-Pituitary-Adrenal Axis Function in Ovine Pregnancy Endocrinology, March 1, 2008; 149(3): 1163 - 1172. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J Watkins, E. Ursell, R. Panton, T. Papenbrock, L. Hollis, C. Cunningham, A. Wilkins, V. H. Perry, B. Sheth, W. Y. Kwong, et al. Adaptive Responses by Mouse Early Embryos to Maternal Diet Protect Fetal Growth but Predispose to Adult Onset Disease Biol Reprod, February 1, 2008; 78(2): 299 - 306. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
). There was a significant relationship (B) between the fetal adrenal CYP17 (y) and IGF-II (x) mRNA expression on d 53–56 of gestation (y = 0.16x + 0.08; r = 0.62; n = 11; P < 0.05) in control twin fetuses.
).