Placental glucose transport in heat-induced fetal growth retardation

Thureen, Patti J.; Trembler, Karen A.; Meschia, Giacomo; Makowski, Edgar L.; Wilkening, Randall B.

doi:10.1152/ajpregu.1992.263.3.r578

Cited by 115 publications

(162 citation statements)

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“…Exposure of pregnant ewes to hyperthermic conditions for approximately 80 days (days 40 to120 p.c.) results in a fetus whose placenta is also growth restricted [40,41]. Similar results are obtained when exposure is for only 55 days (days 37 to 93 p.c.…”

Section: Placental Development In Compromised Pregnanciesmentioning

confidence: 59%

“…Fetal growth in these pregnancies is asymmetric in nature, as evidenced by greater biparietal diameter/abdominal circumference ratios [42]. Furthermore, current evidence indicates that development of FGR in chronically hyperthermic ewes occurs as a consequence of reduction in placental growth in early gestation [41,42,44], making this a model to examine impaired placental development, leading to FGR, comparable to early-onset severe FGR in humans.…”

Section: Placental Development In Compromised Pregnanciesmentioning

confidence: 99%

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The pregnant sheep as a model for human pregnancy

2008

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Successful outcome of human pregnancy not only impacts the quality of infant life and well-being, but considerable evidence now suggests that what happens during fetal development may well impact health and well-being into adulthood. Consequently, a thorough understanding of the developmental events that occur between conception and delivery is needed. For obvious ethical reasons, many of the questions remaining about the progression of human pregnancy can not be answered directly, necessitating the use of appropriate animal models. A variety of animal models exist for the study of both normal and compromised pregnancies, including laboratory rodents, non-human primates and domestic ruminants. While all of these animal models have merit, most suffer from the inability to repetitively sample from both the maternal and fetal side of the placenta, limiting their usefulness in the study of placental or fetal physiology under non-stressed in vivo conditions. No animal model truly recapitulates human pregnancy, yet the pregnant sheep has been used extensively to investigate maternal-fetal interactions. This is due in part to the ability to surgically place and maintain catheters in both the maternal and fetal vasculature, allowing repeated sampling from non-anesthetized pregnancies. Considerable insight has been gained on placental oxygen and nutrient transfer and utilization from use of pregnant sheep. These findings were often confirmed in human pregnancies once appropriate technologies became available. The purpose of this review is to provide an overview of human and sheep pregnancy, with emphasis placed on placental development and function as an organ of nutrient transfer.

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Section: Placental Development In Compromised Pregnanciesmentioning

confidence: 59%

Section: Placental Development In Compromised Pregnanciesmentioning

confidence: 99%

The pregnant sheep as a model for human pregnancy

2008

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“…Several models of IUGR brought about by placental insufficiency or decreased placental mass, such as heat stress and maternal overnutrition, have decreased glucose uptake in IUGR v. control dams (Wallace et al, 2002;Limesand et al, 2007). In the hyperthermia ovine model, reduced glucose transport capacity occurs due to a smaller placenta size and reduced concentrations of glucose transporters per gram of placenta (Thureen et al, 1992;Limesand et al, 2007). In the overnutrition ovine model, reduced glucose transport capacity occurs primarily due to a decreased placental surface area and placental size, whereas glucose transporter density remains similar across treatment groups (Hay, 2006;Wallace et al, 2006).…”

Section: Discussionmentioning

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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“…In general, the size of the placenta is correlated with its glucose and amino acid transfer capacity, which is determined by transporter abundance (reviewed by Regnault et al (2005) and Fowden et al (2006c)). Interruptions in the normal placental growth trajectory caused by carunclectomy (Owens, et al, 1987), heat stress (Thureen et al, 1992), nutrition manipulation (Wallace et al, 2002), or prolonged hypoglycemia (Carver and Hay, 1995) may either increase or decrease glucose and amino acid transporter abundance and hence, the efficiency of placental nutrient-transfer capacity.…”

Section: Placental Formationmentioning

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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Placental glucose transport in heat-induced fetal growth retardation

Cited by 115 publications

References 0 publications

The pregnant sheep as a model for human pregnancy

The pregnant sheep as a model for human pregnancy

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

Litter-size-dependent intrauterine growth restriction in sheep

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