Nutrition of the conceptus: aspects of its regulation

Bassett, J. M.

doi:10.1079/pns19860028

Cited by 18 publications

(6 citation statements)

References 37 publications

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“…Hay et al 1981) as due to the estimation, by Hodgson and co-workers, of glucose use by the whole conceptus, and not the fetal body alone. The need to consider fetal glucose metabolism integrated with all fetal tissues perfused by the fetal cardiovascular system (Bassett et al 1985;Bassett, 1986) gains strong support from the present results, which show that glycolysis within the tissues of the conceptus used only glucose which had first mixed and equilibrated with the conceptus glucose pool. Consumption of fetal glucose by placental tissue has been reported earlier (Hay et al 1981) but quantitative evidence that conceptus lactate from placental glycolysis originates exclusively from the conceptus glucose pool has not been presented previously.…”

Section: Discussionsupporting

confidence: 71%

“…A new analysis of the relevant concepts and experimental approaches (Bassett et al 1985;Bassett, 1986) has shown that to depict glucose metabolism by the somatic fetal tissues separately from that of other, extracorporeal tissues of the conceptus is erroneous and should be abandoned in favour of a pool representing glucose carbon in the whole conceptus. A two-pool model defined clearly in this way then has the unique value of allowing glucose transactions within the whole conceptus to be evaluated (Bassett, 1986). Application to the authors' earlier work (Hodgson et al 1980(Hodgson et al , 1981 helps explain the higher rates of 'fetal' glucose use compared to estimates of glucose use by fetal somatic tissues in other laboratories (e.g.…”

Section: Discussionmentioning

confidence: 99%

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Kinetics of lactate and glucose metabolism in the pregnant ewe and conceptus

Hodgson

Field²

1991

Experimental Physiology

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Two monotocous and two ditocous ewes were infused at 124-130 days of gestation with a mixture of L-[U-14C]lactate and D-[6-3H]glucose via a maternal or umbilical catheter, separate days being used for each infusion. Plateaux-specific radioactivities of plasma lactate and glucose were used to derive a four-pool model describing the fluxes between the lactate and glucose pools of the infused conceptus and mother. The average turnover rate of lactate was 23.3 and 13.2 mg carbon min-1 in the conceptus and 32.0 and 44.0 mg carbon min-1 in the mother for monotocous and ditocous ewes, respectively. Glycolysis rates within both conceptus and mother in all sheep were high, accounting for about 80 and 60% of the respective rates of lactate turnover. The synthesis of glucose from lactate accounted for 13 and 31% of the glucose turnover in the mother in monotocous and ditocous ewes, respectively, but was insignificant in the conceptus. Glycolysis within the conceptus used only glucose which had entered and mixed with the conceptus glucose pool; there was no direct transfer of carbon from the maternal glucose pool to the conceptus lactate pool. This finding is an important validation for the use of tracer methods to determine glucose use within the whole conceptus rather than within fetal corporeal tissues alone.

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Kinetics of lactate and glucose metabolism in the pregnant ewe and conceptus

Hodgson

Field²

1991

Experimental Physiology

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“…Many have suggested that size and functional capacity of the placenta is a major component of maternal constraint of fetal growth and development (Alexander, 1964, Bassett, 1986Owens et al, 1986;Bell et al, 1987;Mellor, 1987). Thus, it was considered important to assess some indicators of those variables in the present study.…”

Section: Discussionmentioning

confidence: 96%

Maternal and fetal influences on uterine and conceptus development in the cow: I. Growth of tissues of the gravid uterus

Ferrell

1991

Journal of Animal Science

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Objectives of this study were to evaluate maternal and fetal influences on development of gravid uterine tissues of cows. Brahman cows with Brahman or Charolais fetuses and Charolais cows with Brahman or Charolais fetuses were used. Cows were killed 232 +/- .5 or 271 +/- .7 d after mating. The gravid uterus of each cow was weighed and dissected into its component parts. Weights of the fetus, fetal membranes, cotyledons, caruncles, and uterus were recorded as were weights of the fetal liver, heart, kidneys, spleen, lungs, stomach complex, intestines, and semitendinosus muscle. Ribonucleic acid, DNA, and protein concentrations in caruncles, cotyledons, liver, heart, kidney, and semitendinosus muscle were determined. Data were analyzed by analysis of variance; breed of cow (C), breed of fetus (F), day of gestation (D), and all interactions were included in the model as fixed effects. Fetal weights were influenced (P less than .003) by C, F, D, and C x D and tended (P = .07) to be influenced by C X F X D. Weight, RNA, DNA, and protein contents of selected fetal tissues followed similar patterns of significance. Thus, both maternal and fetal genotype influenced fetal growth. Greater influences of the maternal system and interrelationships between maternal and fetal systems were observed at the latter stage of gestation. Placentomal (caruncle + cotyledon) weights were greater for Charolais than for Brahman cows (P less than .02) or fetuses (P less than .001) and were greater (P less than .01) at 271 than at 232 d. Caruncular weights followed similar patterns; however, fetal genotype was the only significant source of variation in cotyledonary weight, RNA, DNA, or protein content.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Finally, much of the regulation of placental and fetal growth may be mediated by factors derived within the conceptus itself, with mammal hormones acting as modulators, rather than as primary stimuli (Bassett, 1986;Bell et al, 1987a). The possibility that secretion of or sensitivity to trophic factors in the conceptus were affected by hyperthermia was not tested in this study and will be examined in future experiments.…”

Section: Discussionmentioning

confidence: 99%

Chronic Heat Stress and Prenatal Development in Sheep: I. Conceptus Growth and Maternal Plasma Hormones and Metabolites

Bell

McBride

Slepetis

et al. 1989

Journal of Animal Science

139

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Pregnant ewes were chronically exposed to thermoneutral (TN; 20 degrees C, 30% relative humidity) or hot (H; 40 degrees C 9 h/d, 30 degrees C 15 h/d, 40% relative humidity) environments between d 64 and 136 to 141 of pregnancy. They were sampled for blood at 14-d intervals during this period for measurement of plasma metabolites and hormones, then slaughtered and dissected to measure conceptus weights, dimensions and fetal organ weights. Rectal temperatures of H ewes were elevated .3 to 1.0 C degrees above those of TN ewes throughout the experiment. Voluntary feed intakes were not altered by heat exposure except after 120 d of pregnancy, when feed intake was about 25% lower (P less than .10) by H than by TN ewes. Blood 3-hydroxybutyrate concentrations were not affected by heat, but plasma glucose concentrations were greater in H than in TN animals after 120 d (P less than .05). Placental weight, reduced by 54% (P less than .001) by heat exposure of ewes, was correlated positively with fetal weight and correlated negatively with fetal/placental weight ratio, fetal brain/liver weight ratio and fetal relative heart weight. Late in pregnancy, plasma concentrations of progesterone, cortisol and placental lactogen were reduced (P less than .01) in H ewes, whereas triiodothyronine levels were markedly lower (P less than .03) at all stages of pregnancy. Plasma concentrations of prolactin were elevated dramatically (P less than .01) and a modest increase (P less than .03) in somatotropin levels was recorded in H ewes. These results are consistent with our hypothesis that heat-induced fetal growth retardation is secondary to a primary reduction in placental growth; this could be mediated partly by reduced peripheral activity of thyroid hormones. Heat-induced reductions in secretion of progesterone and ovine placental lactogen more likely were a consequence than a cause of placental stunting.

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Nutrition of the conceptus: aspects of its regulation

Cited by 18 publications

References 37 publications

Kinetics of lactate and glucose metabolism in the pregnant ewe and conceptus

Kinetics of lactate and glucose metabolism in the pregnant ewe and conceptus

Maternal and fetal influences on uterine and conceptus development in the cow: I. Growth of tissues of the gravid uterus

Chronic Heat Stress and Prenatal Development in Sheep: I. Conceptus Growth and Maternal Plasma Hormones and Metabolites

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