Endocrine Abstracts

Type I 5'-monodeiodinase (5'-MDI) converts thyroxine (T4) to triiodothyronine (T3). In fetal sheep, hepatic 5'-MDI activity increases near term in association with the prepartum cortisol surge. This study investigated the effect of maternal dexamethasone treatment, in clinically relevant doses, on hepatic and renal type I 5'-MDI activity and plasma thyroid hormone concentrations in fetal sheep.From 125 days of gestation (term 145 pl...

The morphology of individual ovine placentomes is known to be influenced by several factors including; hypoxia (Gardner et.al, 2002, Placenta 23:459-466), heat stress (Bell et.al, 1987, J.Dev.Phys. 9:17-29) and the fetal and maternal nutrition (McCrabb et.al, 1991, B.J.Nutrition 65:157-168). These conditions are associated with elevated fetal plasma cortisol concentrations. However, the direct effects of fetal cortisol on placental morphology remain unknown. Hence, this study ...

Programming of the HPA axis during prenatal and early postnatal life may explain, in part, the association between low birth weight (BW) and the increased incidence of cardiovascular and metabolic disease in later life. The present study examined the effect of variations in intrauterine growth on HPA axis function, assessed by an insulin-induced hypoglycemic challenge, in 3 and 12 month (m) old pigs.Low BW (<1.5 kg; n=22) and high BW (>1.5 kg; n=25...

Introduction: Increased plasma AVP contributes to the peripheral vasoconstrictor response to acute hypoxaemia in the fetus (Giussani et al. J.Physiol. 477, 81, 1994). We have shown that fetal pre-exposure to umbilical cord compression (UCC) sufficient to restrict fetal blood supply by 30%, markedly blunts the subsequent fetal vasoconstrictor response to hypoxaemia (Gardner et al. Circulation 106: 2278, 2002). This study determined whether this blunting is due to an effect on f...

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In ovine placenta, binucleate cells (BNCs) are formed from trophectodermal uninucleate cells and produce placental lactogen (PL) and pregnancy associated glycoproteins (PAGs). BNC numbers cells are stable throughout most of pregnancy, yet fall abruptly just before term (Wooding et al., 1994), at a time when endogenous fetal cortisol levels are rising. This study looked at the effect of abolishing the normal prepartum cortisol rise by fetal adrenalectomy on the BNC population i...

Synthetic glucocorticoid administration during pregnancy reduces birth weight and increases disease risk in the offspring. This study investigated whether increasing maternal natural corticosterone levels, by endogenous stress or exogenous administration, alters fetal amino acid supply in the mouse.C57BL6/J dams (n=82) were exposed to daily restraint and subcutaneous saline injection (stress) or given corticosterone (cort, 82±11 &#...

Deiodinase enzymes have an important role in thyroid hormone metabolism. Type I 5′-monodeiodinase (D1) converts thyroxine (T4) to triiodothyronine (T3), while type III 5-monodeiodinase (D3) inactivates T3 and produces reverse-T3 (rT3) from T4. In fetal sheep, plasma T3 rises towards term in association with the prepartum cortisol surge. This study investigated the effect of cortisol on tissue de...

Leptin is a hormone produced mainly from adipose tissue, which plays a major role in energy homeostasis. Its receptor Ob-R exists in five splice variants (Ob-Ra, b, c, d and e) with differing signal transduction abilities. The function of leptin and its receptor in development is not yet fully understood. This study determined the expression of leptin and its receptor in a number of fetal endocrine tissues.Tissue samples were obtained from 7 fetal sheep ...

Babies born to mothers with diabetes during pregnancy are exposed to high circulating leptin before birth and, in turn, are at increased risk of developing diabetes in later life. In pancreatic islets isolated from fetal sheep, leptin influences β-cell proliferation in a bimodal manner. This study examined the effect of exogenous leptin infusion and leptin receptor antagonism on pancreatic β-cell mass in the sheep fetus in vivo.<...