Estrogen effects on platelet-activating factor and platelet-activating factor acetylhydrolase activity in rat uterus during the late stages of pregnancy.
The platelet-activating factor (PAF) concentration of the uterus spontaneously increased during pregnancy. When 17alpha-ethynylestradiol (0.25 mg/kg) was administered subcutaneously to pregnant rats for 3 days starting on Day 17 of pregnancy, some rats delivered prematurely on Day 20. However, none of the vehicle-treated (80% dimethylsulfoxide and 20% ethanol) pregnant rats delivered prematurely. The PAF concentration of the uterus in pregnant rats treated with 17alpha-ethynylestradiol was significantly higher than in those treated with vehicle on Days 19 and 20. On the other hand, the specific activity of uterine PAF-acetylhydrolase (PAF-AH) in pregnant rats treated with 17alpha-ethynylestradiol was significantly lower than in those treated with vehicle on Days 19 and 20, and the plasma PAF-AH activity in pregnant rats treated with estrogen was also significantly lower than in treated with vehicle on Days 18, 19, and 20. These findings indicate that estrogen increases PAF concentrations in the rat uterus, and this was correlated with a decrease in PAF-AH in the uterus and plasma. The increase in PAF concentrations in the uterus may be related to premature delivery and labor caused by PAF's known effect on myometrial contraction.
Department of Obstetrics and Gynecology, Kansai Medical University, Osaka, Japan. yasuda@takii.kmu.ac.jp
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Matsubara
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Okada
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Kanzaki
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000818:Animals; D045166:Estradiol Congeners / Q000494:pharmacology*; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D007743:Labor, Obstetric / Q000187:drug effects / Q000502:physiology; D050356:Lipid Metabolism; D010741:Phospholipases A / Q000032:analysis / Q000097:blood*; D010920:Placenta / Q000187:drug effects / Q000201:enzymology*; D010972:Platelet Activating Factor / Q000378:metabolism*; D011247:Pregnancy; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D014599:Uterus / Q000187:drug effects / Q000201:enzymology
D045166:Estradiol Congeners; D010972:Platelet Activating Factor; D004997:Ethinyl Estradiol; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase