Evidence for altered placental blood flow and vascularity in compromised pregnancies

Reynolds, Lawrence P.; Caton, J. S.; Redmer, Dale A.; Grazul-Bilska, Anna T.; Vonnahme, K. A.; Borowicz, P. P.; Luther, J. S.; Wallace, Jacqueline M.; Wu, Guoyao; Spencer, Thomas E.

doi:10.1113/jphysiol.2005.104430

Cited by 313 publications

(222 citation statements)

References 74 publications

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“…maternal nutritional plane, maternal age, heat stress, hypoxic stress, and fetal number) have been developed to better unravel the relationship between uteroplacental blood flow, placental vascularity, and nutrient delivery to the fetus (Kwon et al, 2004;Reynolds et al, 2005). In sheep, increasing uterine blood flow during the last half of gestation is vital for maintaining a continual delivery of sufficient oxygen and nutrients to the exponentially growing fetus (Ford, 1995;Redmer et al, 2004;Reynolds et al, 2006). Maternal nutrient restriction causes aberrations in uterine blood flow and placental vascularity, which is highly associated with the magnitude of fetal growth restriction.…”

Section: Introductionmentioning

confidence: 99%

Dietary melatonin supplementation alters uteroplacental amino acid flux during intrauterine growth restriction in ewes

Lemley

Camacho

Meyer

et al. 2013

Animal

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Dietary melatonin supplementation during mid-to late-gestation increased umbilical artery blood flow and caused disproportionate fetal growth. This melatonin-induced increase in umbilical artery blood flow may alter nutrient availability to the fetus, which may lead to alterations in fetal size. The objectives of the current experiment were to determine amino acid (AA) and glucose concentrations as well as AA and glucose flux across the uteroplacenta using a mid-to late-gestation model of intrauterine growth restriction supplemented with dietary melatonin as a 2 3 2 factorial design. At day 50 of gestation, 32 ewes were supplemented with 5 mg of melatonin (MEL) or no melatonin (CON) and were allocated to receive 100% (adequate; ADQ) or 60% (restricted; RES) of nutrient requirements. On day 130 of gestation, uterine and umbilical blood flows were determined via Doppler ultrasonography during a non-survival surgery. Blood samples were collected under general anesthesia from the maternal saphenous artery, gravid uterine vein, umbilical artery, and umbilical vein for AA analysis and glucose. Total a-AA concentrations in maternal artery and gravid uterine vein were decreased (P , 0.05) in RES v. ADQ fed ewes. Maternal arterial 2 venous difference in total a-AA was increased ( P < 0.01) in RES v. ADQ fed ewes, while total uterine a-AA flux was not different (P . 0.40) across all treatment groups. Fetal venous 2 arterial difference in total a-AA as well as uteroplacental flux of total a-AA were decreased (P , 0.05) in CON-RES v. CON-ADQ, and similar (P . 0.20) in MEL-RES v. CON-ADQ. Maternal concentrations and uterine flux of branched-chain AA (BCAA) were not different across all treatment groups; however, fetal uptake of BCAA was decreased (P , 0.05) in CON-RES v. CON-ADQ, and similar (P . 0.20) in MEL-RES v. CON-ADQ. Uterine uptake of glucose was not different (P > 0.08) across all treatment groups, while uteroplacental uptake of glucose was increased (P < 0.05) in RES v. ADQ ewes. In conclusion, maternal nutrient restriction increased maternal arterial 2 venous difference in total a-AA, while total uterine a-AA flux was unaffected by maternal nutrient restriction. Melatonin supplementation did not impact maternal serum concentrations or uterine flux of glucose or AA; however, melatonin did improve fetal BCAA uptake during maternal nutrient restriction.

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Section: Introductionmentioning

confidence: 99%

Dietary melatonin supplementation alters uteroplacental amino acid flux during intrauterine growth restriction in ewes

Lemley

Camacho

Meyer

et al. 2013

Animal

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“…Foetal growth rate and subsequent birth weight (BWT) of lambs are determined by the genetic background of the foetus which governs its drive for growth, by its paternal genotype which determines placental size, morphology and efficiency of nutrient transfer to the growing foetus, by external environmental conditions such as nutritional status, which affect maternal physiology, and by specific uterine environment-related conditions such as the number of foetuses in the litter (Dickinson et al, 1962;Anthony et al, 2003;Redmer et al, 2004;Safari et al, 2005;Reynolds et al, 2006). Intrauterine growth restriction (IUGR), which leads to the birth of smaller lambs with reduced survival ability, occurs in sheep naturally and can be induced by several means.…”

Section: Introductionmentioning

confidence: 99%

Litter-size-dependent intrauterine growth restriction in sheep

Gootwine

Spencer

Bazer

2007

Animal

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Regulation of foetal development in sheep depends on interactions between the intrinsic capacity of the foetus for growth and the maternal environment. Lambs born in multi-foetus litters have relatively small placentae with fewer cotelydons, and lower birth weights. Litter-size-dependent intrauterine growth restriction (IUGR) is evident at mid gestation when metabolic needs of the conceptus are moderate, and overnutrition of ewes with multiple foetuses does not promote growth of their foetuses to the size of singletons. Those observations suggest that placental and conceptus growth in multi-foetus pregnancies is reprogrammed at mid gestation by an as yet undefined mechanism to attenuate foetal growth. This may protect the foetus from severe nutritional insult during late gestation, when its daily growth rate is at a maximum. In that way, lambs born in large litters with relatively lower birth weights may not experience the long-term physiological insults that can be observed in small lambs born to undernourished ewes.

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“…Growth and development of the fetus involve numerous complex biological events that can be influenced by genetics, epigenetics, maternal maturity, state of maternal nutrition, and environmental temperatures (Redmer et al, 2004). These factors affect implantation and placentation by the conceptus, angiogenesis within the uterus and placenta, utero-placental efficiency of transport of nutrients, and activities of fetal metabolic pathways (Bell and Ehrhardt, 2002;Fowden et al, 2005;Reynolds et al, 2006). All of those events may be influenced by breed characteristics that include maturity of ovulated oocytes, duration of ovulation, implantation and placentation capacity, available uterine space for implantation and placentation, size and efficiency of the placenta, as well as nutritional provision and environmental influences on the sow (Wu et al, 2006).…”

Section: Causes For Within-litter Variation In Birth Weightmentioning

confidence: 99%

Within-litter variation in birth weight: impact of nutritional status in the sow

Yuan

Zhu

Shi

et al. 2015

J. Zhejiang Univ. Sci. B

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Accompanying the beneficial improvement in litter size from genetic selection for high-prolificacy sows, within-litter variation in birth weight has increased with detrimental effects on post-natal growth and survival due to an increase in the proportion of piglets with low birth-weight. Causes of within-litter variation in birth weight include breed characteristics that affect uterine space, ovulation rate, degree of maturation of oocytes, duration of time required for ovulation, interval between ovulation and fertilization, uterine capacity for implantation and placentation, size and efficiency of placental transport of nutrients, communication between conceptus/fetus and maternal systems, as well as nutritional status and environmental influences during gestation. Because these factors contribute to within-litter variation in birth weight, nutritional status of the sow to improve fetal-placental development must focus on the following three important stages in the reproductive cycle: pre-mating or weaning to estrus, early gestation and late gestation. The goal is to increase the homogeneity of development of oocytes and conceptuses, decrease variations in conceptus development during implantation and placentation, and improve birth weights of newborn piglets. Though some progress has been made in nutritional regulation of within-litter variation in the birth weight of piglets, additional studies, with a focus on and insights into molecular mechanisms of reproductive physiology from the aspects of maternal growth and offspring development, as well as their regulation by nutrients provided to the sow, are urgently needed.

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Evidence for altered placental blood flow and vascularity in compromised pregnancies

Cited by 313 publications

References 74 publications

Dietary melatonin supplementation alters uteroplacental amino acid flux during intrauterine growth restriction in ewes

Dietary melatonin supplementation alters uteroplacental amino acid flux during intrauterine growth restriction in ewes

Litter-size-dependent intrauterine growth restriction in sheep

Within-litter variation in birth weight: impact of nutritional status in the sow

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