Nutritional regulation of uteroplacental prostaglandin production and metabolism in pregnant ewes and mares during late gestation.

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.