Relationships between Arachidonic Acid, Uterine Activity and Metabolic Regulation of Placental Lactogen Secretion.

摘要

Placental lactogen concentrations in sheep were observed to vary from + 96% to -56.4% in blood samples collected every 15 minutes. These fluctuations did not appear to result from diurnal or behavioral signals and further studies were conducted to elucidate reasons for the large variations and to determine the metabolic role of oPL during gestation. Fasting, which decreased plasma glucose and increased plasma free fatty acid levels significantly in all ewes, resulted in an increase in mean plasma oPL concentrations in ewes in mid gestation. This effect was due mainly to large increases in two of the five ewes in this group. There was no change or a decrease in plasma oPL concentration with fasting in the other three mid gestation ewes and in another group of ewes in late gestation. The half-life and disappearance rate for glucose following glucose injection did not differ between pregnant and nonpregnant animals. Thus, oPL does not appear to respond consistently to a fast, to changes in plasma glucose or free fatty acids induced by fasting or to have diabetogenic effects. The intravenous administration of 12.5 or 25 mg of arachidonic acid resulted in a significant increase in plasma oPL concentration approximately 120 minutes after injection.