Termination of pregnancy after accelerated lactation in the rat. IV. Relationship to 20alpha-hydroxysteroid dehydrogenase activity and plasma progesterone concentration.
The activity of 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) was assayed in the ovaries of rats after accelerated lactation to determine its relationship to the decrease in progesteron secretion that occurs. When rats were sjbjected to accelerated lactation on Day 9 of pregnancy, activity of the enzyme was only slightly increased by Day 10, but had risen to twice the control level by Day 11, and three times the control level by Day 12. Administration of LH or progesterone prevented the increase in enzyme activity. Progesterone concentration had decreased considerably before the time at which any significant increase in 20alpha-HSD activity was detected. These findings are discussed in relation to the role of 20alpha-HSF in regulating progesterone levels in the rat.
D000818:Animals; D020964:Embryo Loss / Q000201:enzymology*; D047108:Embryonic Development; D005260:Female; D005313:Fetal Death / Q000201:enzymology*; D006913:Hydroxysteroid Dehydrogenases / Q000096:biosynthesis*; D007774:Lactation; D007986:Luteinizing Hormone / Q000494:pharmacology; D010053:Ovary / Q000201:enzymology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood* / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats / Q000502:physiology*
D011374:Progesterone; D007986:Luteinizing Hormone; D006913:Hydroxysteroid Dehydrogenases