Relationships between plasma concentrations of placental lactogen, insulin-like growth factors, metabolites and lamb size in late gestation ewes subject to nutritional supplementation and in their lambs at birth

Gluckman, P. D.; Barry, T. N.

doi:10.1016/0739-7240(88)90032-x

Cited by 18 publications

(5 citation statements)

References 28 publications

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“…PL is considered an important marker of placental integrity and function, with impaired secretion being implicated in altered maternal and fetal metabolism (Freemark & Comer 1989, Handwerger 1991. As gestation advances, PL plasma levels rise (Kelly et al 1974, Oddy & Jenkin 1981, Gluckman & Barry 1988, as a function of total BNC within the placenta (Kappes et al 1992). In our study, heat exposure from 37 dpc, was a critical determinant for circulating oPL concentrations, significantly reduced concentrations suggesting an altered BNC population.…”

Section: Discussionmentioning

confidence: 62%

Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency

Regnault

Orbus²,

Battaglia³

et al. 1999

Journal of Endocrinology

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Pregnant ewes were exposed chronically to thermoneutral (TN; 20 2 C, 30% relative humidity; n=8) or hyperthermic (HT; 40 2 C 12 h/day, 35 2 C 12 h/day, 30% relative humidity, n=6) environments between days 37 and 93 of pregnancy. Ewes were killed following 56 days of exposure to either environment (days in treatment (dit)), corresponding to 93 1 day post coitus (dpc). Maternal core body temperatures (CBT) in HT ewes were significantly elevated above the TN ewes (HT; 39·86 0·1 C vs TN; 39·20 0·1 C; P<0·001). Both groups of animals displayed circadian CBT, though HT ewes had elevated amplitudes (HT; 0·181 0·002 C vs TN; 0·091 0·002 C; P<0·001) and increased phase shift constants (HT; 2100 h vs TN; 1800 h; P<0·001). Ewes exposed to chronic heat stress had significantly reduced progesterone and ovine placental lactogen (oPL) concentrations from 72 and 62 dpc respectively (P<0·05), corresponding to approximately 30 dit. However, when compared with the TN ewes, HT cotyledonary tissue oPL mRNA and protein concentrations were not significantly different (P>0·1). Prolactin concentrations rose immediately upon entry into the HT environment, reaching concentrations approximately four times that of TN ewes, a level maintained throughout the study (HT; 216·31 32·82 vs TN; 54·40 10·0; P<0·0001). Despite similar feed intakes and euglycemia in both groups of ewes, HT fetal body weights were significantly reduced when compared with TN fetuses (HT; 514·6 48·7 vs TN; 703·4 44·8; P<0·05), while placental weights (HT; 363·6 63·3 vs TN; 571·2 95·9) were not significantly affected by 56 days of heat exposure. Furthermore, the relationship between body weight and fetal length, the ponderal index, was significantly reduced in HT fetuses (HT; 3·01 0·13 vs TN; 3·57 0·18; P<0·05). HT fetal liver weights were also significantly reduced (HT; 27·31 4·73 vs TN; 45·16 6·16; P<0·05) and as a result, the brain/liver weight ratio was increased. This study demonstrates that chronic heat exposure lowers circulating placental hormone concentrations. The observation that PL mRNA and protein contents are similar across the two treatments, suggests that reduced hormone concentrations are the result of impaired trophoblast cell development, specifically trophoblast migration. Furthermore, the impact of heat exposure during maximal placental growth is great enough to restrict early fetal development, even before the fetal maximal growth phase (100 dpc-term). These data highlight that intrauterine growth retardation (IUGR) may result primarily from placental trophoblast cell dysfunction, and secondarily from later reduced placental size.

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Section: Discussionmentioning

confidence: 62%

Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency

Regnault

Orbus²,

Battaglia³

et al. 1999

Journal of Endocrinology

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“…One possibility is that increased IGF-I from the maternal liver acts as an endocrine growth factor for greater fetal growth and development. In previous studies, maternal IGF-I concentrations were correlated with the size of the fetus and birth weight (Hall et al 1986, Gluckman & Barry 1988, Lassarre et al 1991, Gluckman et al 1992. The greater maternal IGF-I in rpST-treated gilts may act through similar mechanisms.…”

Section: Discussionmentioning

confidence: 98%

“…In humans, farm animals, and laboratory animals, maternal IGF-I concentrations are correlated with the size of the fetus and birth weight (Hall et al 1986, Gluckman & Barry 1988, Lassarre et al 1991, Gluckman et al 1992. It may be possible, therefore, to increase fetal development and birth weight by increasing maternal IGF-I concentrations during pregnancy.…”

Section: Introductionmentioning

confidence: 99%

Insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein-2 and pregnancy-associated glycoprotein mRNA in pigs with somatotropin-enhanced fetal growth

Boyd¹,

Peacock²,

Koenigsfeld³

et al. 1998

Journal of Endocrinology

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Fetal growth is increased when pregnant gilts are treated with recombinant porcine somatotropin. The mechanism for increased fetal growth was examined by measuring the expression of IGF-I and -II and IGF-binding protein-2 (IGFBP-2) mRNA in liver and reproductive tissues of somatotropin-and saline-treated pregnant gilts.Twenty-four pregnant gilts received daily injections of either saline (control; n=12) or 5 mg recombinant porcine somatotropin (n=12) from day 30 to day 43 of gestation.

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“…Development of the mammalian embryo as well as growth of the fetus has been shown to be modulated by growth factors [40][41][42][43]. It is tempting to speculate that alterations in the concentration of growth factors in the culture medium, or in expression of growth factor ligands and receptors in embryos produced in vitro, may have contributed to the observed difference in fetal size.…”

Section: Embryo Survival and Fetal Development In Catilementioning

confidence: 96%

Transfer of Bovine Embryos Produced in Vivo or in Vitro: Survival and Fetal Development1

Farin

1995

Biology of Reproduction

271

164

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The objectives of the present experiment were to compare survival after transfer of bovine embryos produced in vivo with those produced in vitro and to examine the physical characteristics of fetuses produced from these transfers. Embryos produced in vivo (Holstein x Angus) were recovered from uterine flushings of superovulated heifers 7 days after first artificial insemination, and embryos produced in vitro (Holstein x beef breeds) were collected 7 days after insemination. Embryos were paired by source (in vivo, in vitro), stage (compact morula, blastocyst), and quality grade (excellent = 1, good = 2), and transferred nonsurgically to recipient heifers on Day 7 (+/- 1 day) of the estrous cycle. Pregnancy status was monitored by determination of serum progesterone concentrations, ultrasonography, and palpation through 7 mo of gestation, at which time fetuses were recovered. In comparison with grade 1 embryos produced in vivo, the risk of embryonic death after transfer was similar for grade 2 embryos produced in vivo (p = 0.56) and for grade 1 embryos produced in vitro (p = 0.88). By contrast, grade 2 embryos produced in vitro were at greater (p = 0.04) risk of embryonic death. Embryo loss was associated (p = 0.01) with increased serum concentrations of progesterone in recipients at the time of transfer. At 7 mo of gestation, fetuses from embryos produced in vitro were heavier (p = 0.02) than fetuses from embryos produced in vivo and had skeletal measurements that were disproportionate (p < or = 0.04) to body weight.

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Relationships between plasma concentrations of placental lactogen, insulin-like growth factors, metabolites and lamb size in late gestation ewes subject to nutritional supplementation and in their lambs at birth

Cited by 18 publications

References 28 publications

Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency

Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency

Insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein-2 and pregnancy-associated glycoprotein mRNA in pigs with somatotropin-enhanced fetal growth

Transfer of Bovine Embryos Produced in Vivo or in Vitro: Survival and Fetal Development1

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