Nutritional regulation of uteroplacental prostaglandin production and metabolism in pregnant ewes and mares during late gestation.
Abstract: Prostaglandins (PGs) are produced by a variety of uteroplacental tissues during pregnancy and are released into the fetal fluid sacs and both the uterine and umbilical circulations. Uterine PG output increases towards term and is enhanced by maternal undernutrition in pregnant ewes and mares. In both species, withdrawal of food but not water for 30-48 h increases uterine venous PG levels and the uterine venous arterial concentration differences in PGE and 13, 14, dihydro-15-keto-prostaglandin F2 alpha (PGFM), the stable metabolite of PGF2 alpha. The increments in uterine V-A concentration differences in PGE and PGFM increase towards term and are associated with raised plasma PG levels in the fetal circulation. The PG changes observed during fasting are closely related to the fall in plasma glucose and the rise in plasma FFA in peripheral plasma. When normal metabolite levels are restored either by refeeding or glucose infusion, there is a rapid fall in PG levels with a narrowing of the uterine V-A concentration differences in the ewe and mare. When the data from all the animals are combined, there is an inverse correlation between uterine glucose uptake and PGFM output in both the pregnant ewe and mare. The availability of glucose and FFA to the gravid uterus therefore has an important role in controlling uteroplacental PG production and metabolism in late gestation although the specific steps in biochemical pathways regulated by these metabolites remain unclear. In the ewe, fasting increases uterine contractility and leads to early delivery of viable lambs in animals close to term (> 95% gestation), whereas in the mare it causes premature delivery of non-viable foals in most animals in late gestation (> 80% gestation). Nutritionally induced changes in uteroplacental PG production and metabolism therefore have important consequences for the outcome of pregnancy and may have a pivotal role in the induction of labour both before and at normal term.
Publication Date: 1994-01-01 PubMed ID: 7995343DOI: 10.1055/s-0029-1211285Google Scholar: Lookup
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- Journal Article
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- Non-U.S. Gov't
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Summary
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This research investigated how nutrition affects the production and metabolism of prostaglandins—hormone-like compounds—in the uteroplacental tissues in pregnant ewes (female sheep) and mares (female horses) during late gestation. It found that food deprivation can raise the levels of these substances and potentially lead to early or problematic births, depending on the species. The specific biochemical pathways affected by certain nutrients still require further understanding.
Prostaglandins and Pregnancy
- Prostaglandins (PGs) are naturally occurring compounds with hormone-like effects that are produced by various tissues during pregnancy.
- These substances are present in the fetal fluid sacs and circulate within the uterine and umbilical cord systems.
- The study observes that the production of prostaglandins in the uterus increases as pregnancy approaches its term, particularly in conditions of maternal undernutrition.
Effect of Fasting on Prostaglandin Levels
- In pregnant ewes and mares, fasting (the absence of food but not water) for 30 to 48 hours reportedly increases the levels of prostaglandins within uterine venous circulation.
- These increased prostaglandin levels are associated with elevated plasma prostaglandin levels within the fetal bloodstream.
- The study draws a direct relation between the observed spikes in prostaglandin levels during fasting and a decrease in plasma glucose alongside an increase in plasma Free Fatty Acid (FFA) in peripheral plasma.
Restoration of Normal Prostaglandin Levels
- A return to normal prostaglandin levels can be achieved either through the restoration of food intake after a period of fasting or via the infusion of glucose.
- When normal metabolite levels are reinstated through refeeding or glucose infusion, prostaglandin levels rapidly decrease, and the concentration differences in the uterus narrow for both ewes and mares.
Impact on Pregnancy Outcomes
- In ewes, fasting can cause early births of viable lambs for those animals close to term. In mares, however, food deprivation leads to premature births of non-viable foals for the majority of the animals in late gestation.
- Therefore, the study suggests that the availability of glucose and FFAs—that may control uteroplacental prostaglandin production and metabolism during the late stages of pregnancy—could significantly impact the outcomes of those pregnancies.
- This research underscores the need for further investigation into the biochemical pathways regulated by these important metabolites, as they may play a fundamental role in labor induction either pre-term or at the standard gestation term.
Cite This Article
APA
Fowden AL, Ralph MM, Silver M.
(1994).
Nutritional regulation of uteroplacental prostaglandin production and metabolism in pregnant ewes and mares during late gestation.
Exp Clin Endocrinol, 102(3), 212-221.
https://doi.org/10.1055/s-0029-1211285 Publication
Researcher Affiliations
- Dept. of Physiology, Monash University, Clayton, Victoria, Australia.
MeSH Terms
- Animal Nutritional Physiological Phenomena
- Animals
- Female
- Gestational Age
- Horses / metabolism
- Placenta / metabolism
- Pregnancy
- Prostaglandins / biosynthesis
- Prostaglandins / metabolism
- Sheep / metabolism
- Uterus / metabolism
Citations
This article has been cited 3 times.- Burton GJ, Fowden AL, Thornburg KL. Placental Origins of Chronic Disease. Physiol Rev 2016 Oct;96(4):1509-65.
- Fowden AL, Ward JW, Wooding FP, Forhead AJ, Constancia M. Programming placental nutrient transport capacity. J Physiol 2006 Apr 1;572(Pt 1):5-15.
- Fowden AL, Taylor PM, White KL, Forhead AJ. Ontogenic and nutritionally induced changes in fetal metabolism in the horse. J Physiol 2000 Oct 1;528 Pt 1(Pt 1):209-19.
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