scholarly journals Influence of cortisol on adipose tissue development in the fetal sheep during late gestation

2003 ◽  
Vol 176 (1) ◽  
pp. 23-30 ◽  
Author(s):  
A Mostyn ◽  
S Pearce ◽  
H Budge ◽  
M Elmes ◽  
AJ Forhead ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Gestational Age ◽  
Plasma Cortisol ◽  
Late Gestation ◽  
Protein Abundance ◽  
Tissue Development ◽  
Voltage Dependent Anion Channel ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Adipose Tissue Development

The present study examined the extent to which the late gestation rise in fetal plasma cortisol influenced adipose tIssue development in the fetus. The effect of cortisol on the abundance of adipose tIssue mitochondrial proteins on both the inner (i.e. uncoupling protein (UCP)1) and outer (i.e. voltage-dependent anion channel (VDAC)) mitochondrial membrane, together with the long and short forms of the prolactin receptor (PRLR) protein and leptin mRNA was determined. Perirenal adipose tIssue was sampled from ovine fetuses to which (i) cortisol (2-3 mg/day for 5 days) or saline was infused up to 127-130 days of gestation, and (ii) adrenalectomised and intact controls at between 142 and 145 days of gestation (term=148 days). UCP1 protein abundance was significantly lower in adrenalectomised fetuses compared with age-matched controls, and UCP1 was increased by cortisol infusion and with gestational age. Adrenalectomy reduced the concentration of the long form of PRLR, although this effect was only significant for the highest molecular weight isoform. In contrast, neither the short form of PRLR, VDAC protein abundance or leptin mRNA expression was significantly affected by gestational age or cortisol status. Fetal plasma triiodothyronine concentrations were increased by cortisol and with gestational age, an affect abolished by adrenalectomy. When all treatment groups were combined, both plasma cortisol and triiodothyronine concentrations were positively correlated with UCP1 protein abundance. In conclusion, an intact adrenal is necessary for the late gestation rise in UCP1 protein abundance but cortisol does not appear to have a major stimulatory role in promoting leptin expression in fetal adipose tIssue. It remains to be established whether effects on UCP1 protein are directly regulated by cortisol alone or mediated by other anabolic fetal hormones such as triiodothyronine.

scholarly journals Ontogeny and Effects of Hypothalamic Pituitary Disconnection on Formation of Inositol Trisphosphate in Fetal Sheep Pituitary Cells

Endocrinology ◽  
2007 ◽  
Vol 148 (3) ◽  
pp. 1440-1444 ◽  
Author(s):  
Luke C. Carey ◽  
Stephen B. Tatter ◽  
James C. Rose
Keyword(s):  
Gestational Age ◽  
Plasma Cortisol ◽  
Inositol Trisphosphate ◽  
Second Messenger ◽  
Late Gestation ◽  
Pituitary Cells ◽  
Fetal Sheep ◽  
The Impact ◽  
Pituitary Adrenal Axis ◽  
Sheep Fetus

In late gestation fetal sheep, the pituitary becomes increasingly responsive to stimulation by arginine vasopressin (AVP). This change appears to be one important factor mediating the plasma cortisol surge, a critical developmental event. It is not known precisely why pituitary corticotropes become more responsive at this time. In this study we examined the possibility that changes in second messenger generation [inositol trisphosphate (IP3)] are responsible. Two studies were undertaken. The first was an ontogeny study, where pituitaries were isolated from 100-, 120-, and 140-d gestational age (dGA) fetal sheep. Cells were cultured, stimulated with AVP, and the formation of IP3 assessed. The amount of IP3 generated increased with gestational age (percent increases from unstimulated controls were 4.6, 11.5, and 21.5 for 100, 120, and 140 dGA, respectively), with significant differences between the 140-dGA group and both earlier groups apparent. The second study examined the impact of 120-dGA hypothalamo-pituitary disconnection (HPD), which prevents corticotrope maturation, on responsiveness of pituitary cells isolated from 140-dGA fetuses. Cells were stimulated with AVP, and the formation of IP3 and secretion of ACTH were assessed. Significantly less IP3 was formed, and ACTH secreted in cells from HPD compared with control fetuses (IP3 and ACTH levels were 50% and 35% lower, respectively). Results from the HPD study demonstrate that the ontogenic changes in IP3 after AVP require an intact hypothalamic-pituitary-adrenal axis. These findings suggest that heightened second messenger generation may be a key reason for increased ACTH secretory responsiveness to AVP in the late gestation sheep fetus.

Blood pressure and heart rate in the ovine fetus: ontogenic changes and effects of fetal adrenalectomy

1999 ◽  
Vol 276 (1) ◽  
pp. H248-H256 ◽  
Author(s):  
Nobuya Unno ◽  
Chi H. Wong ◽  
Susan L. Jenkins ◽  
Richard A. Wentworth ◽  
Xiu-Ying Ding ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Plasma Cortisol ◽  
Time Windows ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Long Term Study ◽  
Arterial Blood ◽  
Ovine Fetus

Ontogenic changes in baseline and 24-h rhythms of fetal arterial blood pressure (FABP) and heart rate (FHR) and their regulation by the fetal adrenal were studied in 18 fetal sheep chronically instrumented at 109–114 days gestation (GA). In the long-term study, FABP and FHR were continuously recorded from 120 days GA to spontaneous term labor (>145 days GA) in five animals. Peak times (PT) and amplitudes (Amp) of cosinor analysis were compared at 120–126, 127–133, and 134–140 days GA. Consistent, significant linear increases in FABP and linear decreases in FHR were observed in all fetuses. Significant 24-h rhythms in FABP and FHR were observed during all the time windows. In the adrenalectomy study, to test the hypothesis that fetal cortisol plays a key role in cardiovascular maturation, fetal adrenals were removed in eight animals (ADX); sham fetal adrenalectomy was performed on five animals (Con). Cortisol (4 μg/min) was infused intravenously in four ADX fetuses from day 7postsurgery for 7 days (ADX+F). No significant changes in PT and Amp in FABP and FHR were observed. Plasma cortisol levels remained low in Con and ADX fetuses (<4.9 ng/ml). Cortisol infusion increased fetal plasma cortisol to 22.3 ± 3.2 ng/ml (mean ± SE) on day 13 in ADX+F fetuses. FABP increased in control and ADX+F but not ADX fetuses; FHR decreased in control and ADX but rose in ADX+F fetuses. These results suggest that, in chronically instrumented fetal sheep at late gestation, 1) increases in FABP and decreases in FHR are maintained consistently from 120 to 140 days GA, with distinct 24-h rhythms, the PT and Amp of which remain unchanged, and 2) the physiological increase in FABP is dependent on the fetal adrenal; bilateral removal of the fetal adrenals does not prevent the ability of cortisol to produce a sustained increase in FABP.

Regulation of lung liquid secretion by arginine vasopressin in fetal sheep

1990 ◽  
Vol 258 (1) ◽  
pp. R104-R111 ◽  
Author(s):  
M. J. Wallace ◽  
S. B. Hooper ◽  
R. Harding
Keyword(s):  
Gestational Age ◽  
Arginine Vasopressin ◽  
Plasma Cortisol ◽  
Fetal Lung ◽  
Inhibitory Effect ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Fetal Asphyxia ◽  
Lung Liquid ◽  
Secretion Rates

We have investigated the influence of gestational age on the inhibition of fetal lung liquid secretion by arginine vasopressin (AVP). In eight fetal sheep, lung liquid secretion rates were measured before and during infusion of AVP (300 mu.kg-1.h-1) at gestational ages between 110 and 148 days. During infusions, the concentration of AVP in fetal plasma increased from less than 8.7 +/- 0.2 pg/ml to 848.7 +/- 75.1 pg/ml. Fetal plasma epinephrine concentrations were not altered during AVP infusion. Infusions of AVP had no effect on fetal lung secretion before 135 days of gestation; they caused a 40.8% inhibition between 136 and 140 days, and at ages greater than 140 days induced an inhibition of 78.4%. In two ewes during labor, AVP infusion caused either a complete inhibition of secretion or reabsorption of lung liquid. The inhibitory effect of AVP increased in an exponential-like fashion with increasing gestational age and appeared to parallel the preparturient rise in fetal plasma cortisol concentrations. Our results indicate that AVP may be involved in the clearance of lung liquid at term and that AVP is unlikely to mediate the inhibitory effect of fetal asphyxia on lung liquid secretion, at least until after 135 days of gestation.

Thyroid hormones and the mRNA of the GH receptor and IGFs in skeletal muscle of fetal sheep

2002 ◽  
Vol 282 (1) ◽  
pp. E80-E86 ◽  
Author(s):  
A. J. Forhead ◽  
J. Li ◽  
R. S. Gilmour ◽  
M. J. Dauncey ◽  
A. L. Fowden
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Thyroid Hormones ◽  
Gestational Age ◽  
Plasma Cortisol ◽  
Mrna Abundance ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Igf I ◽  
I Gene

Thyroid hormones are required for the normal development of skeletal muscle in utero, although their mechanism of action is poorly understood. The present study examined the effects of the thyroid hormones on the gene expression of the growth hormone receptor (GHR) and the insulin-like growth factors (IGFs) IGF-I and IGF-II, in skeletal muscle of fetal sheep during late gestation (term 145 ± 2 days) and after manipulation of plasma thyroid hormone concentration. Thyroidectomy at 105–110 days of gestation suppressed muscle GHR and IGF-I gene expression in fetuses studied at 127–130 and 142–145 days. Muscle GHR mRNA abundance remained unchanged with increasing gestational age in intact and thyroidectomized fetuses. In the intact fetuses, a decrease in muscle IGF-I gene expression was observed between 127–130 and 142–145 days, which coincided with the normal prepartum surges in plasma cortisol and triiodothyronine (T3). At 127–130 days, downregulation of muscle IGF-I mRNA abundance was induced prematurely in intact fetuses by an infusion of cortisol for 5 days (2–3 mg · kg−1 · day−1 iv), which increased plasma cortisol and T3 concentrations to values seen near term. However, increasing plasma T3 alone by an infusion of T3 for 5 days (8–12 μg · kg−1 · day−1 iv) in intact fetuses at this age had no effect on GHR or IGF-I gene expression in skeletal muscle. In the thyroidectomized fetuses, no additional change in the low level of muscle IGF-I mRNA abundance was seen with increasing gestational age, but at 127–130 days, IGF-I gene expression was reduced further when plasma cortisol and T3 concentrations were increased by exogenous cortisol infusion. Muscle IGF-II mRNA abundance was not affected by thyroidectomy, gestational age, or exogenous hormone infusion. These findings show, in the sheep fetus, that thyroid hormones may influence the growth and development of skeletal muscle via changes in the local activity of the somatotrophic axis.

scholarly journals In Vivo Evidence for Stimulation of Placental, Myometrial, and Endometrial Prostaglandin G/H Synthase 2 by Fetal Cortisol Replacement after Fetal Adrenalectomy

Endocrinology ◽  
2001 ◽  
Vol 142 (9) ◽  
pp. 3857-3864 ◽  
Author(s):  
W. X. Wu ◽  
X. H. Ma ◽  
N. Unno ◽  
P. W. Nathanielsz
Keyword(s):  
Plasma Cortisol ◽  
Treated Group ◽  
Late Gestation ◽  
Premature Labor ◽  
Indirect Pathway ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Estrogen Synthesis ◽  
Stimulation Of

Abstract Fetal glucocorticoid-induced premature labor in sheep is an established model of premature labor. However, the pathways by which fetal cortisol triggers subsequent maternal endocrine changes, including enhanced PG synthesis, leading to labor are unclear. The current study was undertaken to determine whether cortisol administration to adrenalectomized fetuses to clamp fetal cortisol at levels present early in the late gestation rise, which are inadequate to produce labor, can stimulate placental, myometrial, and endometrial prostaglandin G/H synthase 2 mRNA and protein expression. At 109–113 d gestation, fetal sheep adrenals were removed (n = 8), or sham surgery was performed (n = 4). From d 6 postadrenalectomy, maternal and fetal plasma cortisol were determined daily by RIA. From d 7 postadrenalectomy, cortisol (4 μg/min) was continuously infused iv to four adrenalectomized fetuses. Endometrium, myometrium, and placentome were collected from all three groups of ewes (n = 4 for each group), and total RNA and proteins were extracted from each intrauterine tissue and analyzed by Northern and Western for prostaglandin G/H synthase 2 mRNA and protein. P45017α hydroxylase mRNA was analyzed in the placentome by Northern blot. Data were analyzed by ANOVA. Plasma cortisol levels remained low in sham-operated and adrenalectomized fetus, whereas during cortisol infusion to adrenalectomized and cortisol-treated fetuses, plasma cortisol increased to the late gestation level. After adrenalectomy, prostaglandin G/H synthase 2 did not change in any tissue studied. Fetal plasma cortisol replacement to late gestation levels increased prostaglandin G/H synthase 2 to levels similar to term levels in all three tissues. PGHS1 mRNA and protein did not change in any group studied. There was a minimal increase in P45017α hydroxylase mRNA in the placentome in the adrenalectomized and cortisol-treated group. Cortisol- induced labor further increased P45017α hydroxylase mRNA in the placentome compared with that in adrenalectomized and cortisol-treated animals. These data provide evidence for in vivo cortisol up-regulation of prostaglandin G/H synthase 2, but not PGHS1, in late gestation in the ovine placentome, myometrium, and endometrium. As stimulation of the estrogen biosynthetic pathway was minimal in the adrenalectomized and cortisol-treated group, these data provide support for the concept that cortisol has a direct effect on prostaglandin G/H synthase 2 expression in addition to its classical indirect pathway on prostaglandin G/H synthase 2 as a result of estrogen synthesis.

scholarly journals Developmental Control of Iodothyronine Deiodinases by Cortisol in the Ovine Fetus and Placenta Near Term

Endocrinology ◽  
2006 ◽  
Vol 147 (12) ◽  
pp. 5988-5994 ◽  
Author(s):  
Alison J. Forhead ◽  
Katrina Curtis ◽  
Ellen Kaptein ◽  
Theo J. Visser ◽  
Abigail L. Fowden
Keyword(s):  
Adipose Tissue ◽  
Thyroid Hormones ◽  
Plasma Cortisol ◽  
Late Gestation ◽  
Fetal Sheep ◽  
Perirenal Adipose Tissue ◽  
Deiodinase Activity ◽  
Serum T4 ◽  
Ovine Fetus ◽  
Near Term

Preterm infants have low serum T4 and T3 levels, which may partly explain the immaturity of their tissues. Deiodinase enzymes are important in determining the bioavailability of thyroid hormones: deiodinases D1 and D2 convert T4 to T3, whereas deiodinase D3 inactivates T3 and produces rT3 from T4. In human and ovine fetuses, plasma T3 rises near term in association with the prepartum cortisol surge. This study investigated the developmental effects of cortisol and T3 on tissue deiodinases and plasma thyroid hormones in fetal sheep during late gestation. Plasma cortisol and T3 concentrations in utero were manipulated by exogenous hormone infusion and fetal adrenalectomy. Between 130 and 144 d of gestation (term 145 ± 2 d), maturational increments in plasma cortisol and T3, and D1 (hepatic, renal, perirenal adipose tissue) and D3 (cerebral), and decrements in renal and placental D3 activities were abolished by fetal adrenalectomy. Between 125 and 130 d, iv cortisol infusion raised hepatic, renal, and perirenal adipose tissue D1 and reduced renal and placental D3 activities. Infusion with T3 alone increased hepatic D1 and decreased renal D3 activities. Therefore, in the sheep fetus, the prepartum cortisol surge induces tissue-specific changes in deiodinase activity that, by promoting production and suppressing clearance of T3, may be responsible for the rise in plasma T3 concentration near term. Some of the maturational effects of cortisol on deiodinase activity may be mediated by T3.

Effects of fetal ovine adrenalectomy on sympathetic and baroreflex responses at birth

2002 ◽  
Vol 283 (2) ◽  
pp. R460-R467 ◽  
Author(s):  
Jeffrey L. Segar ◽  
Timothy Van Natta ◽  
Oliva J. Smith
Keyword(s):  
Plasma Cortisol ◽  
Late Gestation ◽  
Renal Nerve ◽  
Baroreflex Control ◽  
Fetal Sheep ◽  
Cesarean Section Delivery ◽  
Fetal Plasma ◽  
Arterial Blood ◽  
Baroreflex Function ◽  
Before And After

Studies were performed to test the hypothesis that the absence of adrenal glucocorticoids late in gestation alters sympathetic and baroreflex responses before and immediately after birth. Fetal sheep at 130–131 days gestation (term 145 days) were subjected to bilateral adrenalectomy before the normal prepartum increase in plasma cortisol levels. One group of fetuses ( n = 5) received physiological cortisol replacement with a continuous infusion of hydrocortisone (2 mg · day−1 · kg−1 for 10 days), whereas the other group received 0.9% NaCl vehicle ( n = 5). All animals underwent a second surgery 48 h before the study for placement of a renal nerve recording electrode. Heart rate (HR), mean arterial blood pressure (MABP), renal sympathetic nerve activity (RSNA), and baroreflex control of HR and RSNA were studied before and after cesarean section delivery. At the time of study (140–141 days gestation), fetal plasma cortisol concentration was undetectable in adrenalectomized (ADX) fetuses and 58 ± 9 ng/ml in animals receiving cortisol replacement (ADX + F). Fetal and newborn MABP was significantly greater in ADX + F relative to ADX animals. One hour after delivery, MABP increased 13 ± 3 mmHg and RSNA increased 91 ± 12% above fetal values in ADX + F (both P < 0.05) but remained unchanged in ADX lambs. The midpoint pressures of the fetal HR and RSNA baroreflex function curves were significantly greater in ADX + F (54 ± 3 and 56 ± 3 mmHg for HR and RSNA curves, respectively) than ADX fetuses (45 ± 2 and 46 ± 3 mmHg). After delivery, the baroreflex curves reset toward higher pressure in ADX + F but not ADX lambs. These results suggest that adrenal glucocorticoids contribute to cardiovascular regulation in the late-gestation fetus and newborn by modulating arterial baroreflex function and sympathetic activity.

scholarly journals Cortisol infusion in late-gestation hypothalamo-pituitary disconnected sheep fetus restores pituitary cell responsiveness to arginine vasopressin

2009 ◽  
Vol 296 (2) ◽  
pp. E300-E304 ◽  
Author(s):  
Luke C. Carey ◽  
Stephen B. Tatter ◽  
James C. Rose
Keyword(s):  
Signal Transduction ◽  
Arginine Vasopressin ◽  
Plasma Cortisol ◽  
Pituitary Cell ◽  
Late Gestation ◽  
Pituitary Cells ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Inositol 1,4,5 Trisphosphate ◽  
Sheep Fetus

Corticotrophs in the fetal sheep become increasingly responsive to arginine vasopressin (AVP) in late gestation. We previously reported that this may be due in part to corresponding increases in signal transduction (inositol 1,4,5-trisphosphate, IP3). These ontogenic changes are prevented by hypothalamo-pituitary disconnection (HPD), which also prevents fetal plasma cortisol concentrations from increasing in late gestation. This led us to hypothesize that cortisol is involved in mediating the changes in pituitary responsiveness. HPD was performed on fetal sheep at 120 days gestational age (dGA). Half of the HPD fetuses were infused with cortisol for 3 days beginning at 135–137 dGA (HPD+C). The remaining HPD fetuses and a group of sham-operated control fetuses were infused with saline. Pituitary cells were isolated and cultured. After 48 h, a subset of cells was stimulated with 100 nM AVP for 2 h, and the medium was collected for ACTH analysis. Another subset of cells was stimulated with 100 nM AVP for 30 min, and the formation of IP3 was determined. Plasma cortisol concentrations increased rapidly within the first 6 h after infusion (5.2 ± 1.9 to 29.7 ± 4.9 ng/ml) but did not increase thereafter. Cells from HPD+C and sham-operated fetuses secreted significantly more ACTH than those from HPD fetuses (% increase from control: 33.0 ± 8.8%, 47.9 ± 10.6%, and 11.9 ± 2.4%, respectively). IP3 formation was significantly increased in cells from HPD+C and sham-operated compared with HPD fetuses (% increase from control: 17.7 ± 4.4%, 18.9 ± 4.3%, and 4.6 ± 1.5%, respectively). These findings support the idea that cortisol plays a role in mediating the increase in pituitary responsiveness to AVP in the late-gestation fetal sheep.

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