J Wallace

..abstract truncated at 250 words)..

..This was the only isoform to demonstrate nutritionally related changes in it subcellular compartmentation suggesting that it may mediate some aspects of the change in fetal growth rate...

..Thus, progesterone did not directly affect the growth of the fetal cotyledon but may have influenced placental vascularity, blood flow or nutrient transfer capacity or alternatively the development of the embryonic inner cell mass...

..In addition, the paradigm provides a robust model of placental growth restriction that replicates many of the key features of human intrauterine growth restriction per se...

..This confirms that the small size of the placenta per se is the major limitation to placental glucose transfer in the overnourished adolescent pregnant sheep...

..It remains to be established whether these effects are due wholly to alterations in maternal metabolism or if they also reflect an effect of bGH and/or the IGF system at the level of the uteroplacenta...

..This indicates that increased fetal glucose clearance and/or insulin sensitivity may be operating as compensatory mechanisms to preserve normal fetal metabolism while fetal growth is sacrificed...

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..Maintained utilization of these substrates, in a substrate-deficient environment, suggests increased sensitivities to metabolic signals, which may play a role in the development of metabolic diseases in later adult life...

..Thus, adult sheep appear to be relatively insensitive to the oversupply of nutrients during pregnancy and have the ability to meet the nutrient requirements for normal conceptus growth in spite of their increased adiposity...

..Thus, while the underlying mechanisms differ, maternal intake at both ends of the nutritional spectrum is a powerful determinant of fetal growth in pregnant adolescents...

..Treatment during late pregnancy has a modest effect on fetal growth independent of placental size and a profound effect on fetal adiposity, which may have implications beyond the fetal period...

..The data imply that it is high-energy intakes that are the primary cause of impaired placental development and adverse pregnancy outcome in rapidly growing adolescent sheep...

..01) but the timing of maximum peak concentrations was similar. Peak testosterone concentrations were lower (P < 0.05) in growth-restricted than in normal male lambs...

..These data are commensurate with the reported decrease in placental angiogenic growth factor expression at mid gestation, and, indicate that attenuated UtBF is an early defect in this adolescent paradigm...

..01). Thus, a high maternal nutrient intake during adolescent pregnancy had a negative influence on ovarian follicular development in fetuses as determined during late gestation...

..The presence of leptin protein and leptin receptor gene expression in the placenta suggests that leptin could be involved in nutrient partitioning during placental and/or fetal development...

..Finally, the consequences of this form of inappropriate nutrient partitioning on the growth and development of the fetus and neonate are described with particular emphasis on the reproductive axis...

..Thus, over-nourishing adolescent sheep is associated with a major restriction in placental growth which mediates a gradual slowing of fetal growth during the final third of pregnancy...

..The latter effect was independent of gonadotrophin secretion.Crown..

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..Similarly, basal and oxytocin-stimulated endometrial PGF2 alpha release during a 4 h incubation were higher (P < 0.01) in pregnant postpartum versus control recipients.(ABSTRACT TRUNCATED AT 250 WORDS)..

..At the other end of the nutritional spectrum, undernourishing the adolescent sheep to gradually deplete nutrient reserves, results in fetal growth restriction which is independent of alterations in placental mass...

..Such changes provide a potential mechanism for the prenatal origins of postnatal energy balance dysregulation and obesity...

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..We tested the hypotheses that ghrelin and its functional receptor, GHSR-1a, are present in tissues of the ovine placenta, and that their expression is linked to the stage of development...

..Restricted placental growth and reduced biosynthesis may account for reduced progesterone in day 130 H+IUGR ewes...

..This may impact placental vascularity and explain why uteroplacental mass, blood flow, and nutrient uptake are compromised in late pregnancy, resulting in low-birth-weight offspring...

..01). Thus, overnourishing pregnant adolescent sheep preserves fat deposition in their growth-restricted fetuses, which may have implications for neonatal thermogenesis and for programming of postnatal adiposity...

..These observations indicate that reduced placental size at term may be due to reduced placental cell proliferation and possibly increased apoptosis occurring much earlier in gestation...

..Placental blood flow and vascular development are thus potential therapeutic targets in compromised pregnancies...