title: Thromboxane and prostacyclin levels in fetal rabbit brain and placenta after intrauterine partial ischemic episodes.
abstract: The appearance of arachidonic acid (AA) oxidation products in fetal rabbit brain and placenta under normal or partial short-term ischemic episodes induced by placental blood vessel restriction was examined. Intracerebral administration of [3H]AA into close-to-term rabbit fetuses gave rise to radioactively labeled prostaglandin (PG) E2, thromboxane B2, and 6-keto-PGF1 alpha metabolites as detected by HPLC analysis. A significant increase of 20-30% of [3H]AA precursor into eicosanoids was detected in brain of fetuses after 2-h restriction. The thromboxane B2 and 6-keto-PGF1 alpha levels were determined by radioimmunoassay technique over a period of 48 h following ischemic episodes. Thromboxane B2 content in affected animals was higher by five- and twofold at 3 h over control fetal brain and placental tissue values, respectively, and remained significantly higher for 24 h. 6-Keto-PGF1 alpha levels reached a peak value that was greater by 2.5- and 1.5-fold at 6 h for the ischemic brain and placental tissue, respectively, compared with control fetuses. PGE2 levels were less affected, attaining a maximum of 1.9- and 1.1-fold in brain and placenta correspondingly. The thromboxane/prostacyclin ratio reached a maximum in the brain after approximately 3 h, while that in the placenta continued to rise even after 20 h. Persisting high levels of thromboxane are indicative of cerebral vasoconstriction and may suggest possible damaging effects.
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Goldin
authors.forename: S
authors.initials: S
authors.lastname: Harel
authors.forename: A
authors.initials: A
authors.lastname: Tomer
authors.forename: E
authors.initials: E
authors.lastname: Yavin
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D015777:Eicosanoids / Q000378:metabolism; D005314:Embryonic and Fetal Development; D011464:Epoprostenol / Q000378:metabolism*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011817:Rabbits; D012016:Reference Values; D013931:Thromboxanes / Q000378:metabolism*
chemical_list: D001095:Arachidonic Acids; D015777:Eicosanoids; D013931:Thromboxanes; D016718:Arachidonic Acid; D011464:Epoprostenol