Significance of follicular cyclooxygenase and lipoxygenase pathways of metabolism of arachidonate in sheep.
Concurrent changes in concentrations of a product of the cyclooxygenase (prostaglandin [PG] F2 alpha) and lipoxygenase (leukotriene [LT] B4) routes of metabolism of arachidonic acid were measured by radioimmunoassay within the wall of periovulatory ovine follicles. Increased concentrations of PGF2 alpha were detected within follicles before, during and following the time of ovulation. A significant rise in LTB4 was not observed until after follicular rupture had occurred. Inhibition of synthesis of PGF2 alpha by indomethacin was associated with a complete blockade of ovulation. Nordihydroguaiaretic acid, an inhibitor of 5-lipoxygenase, had no effect on ovulation. Periovulatory administration of either drug did not alter sera profiles of progesterone during subsequent luteal phases. These results reconfirm the importance of the cyclooxygenase system in the mechanism of ovulation. It does not appear that follicular LTB4 is a key component in the processes of ovulation or luteinization in sheep.
Carvalho
C B
CB
Dept. of Animal Science, University of Wyoming, Laramie 82071.
Yeik
B S
BS
Murdoch
W J
WJ
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D003338:Corpus Luteum / Q000187:drug effects / Q000378:metabolism; D015237:Dinoprost / Q000096:biosynthesis; D005260:Female; D007213:Indomethacin / Q000494:pharmacology; D007975:Leukotriene B4 / Q000096:biosynthesis; D008084:Lipoxygenase / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors; D009637:Masoprocol / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects / Q000201:enzymology*; D010060:Ovulation / Q000187:drug effects; D011374:Progesterone / Q000096:biosynthesis; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*
D001095:Arachidonic Acids; D016859:Lipoxygenase Inhibitors; D007975:Leukotriene B4; D016718:Arachidonic Acid; D011374:Progesterone; D009637:Masoprocol; D015237:Dinoprost; D008084:Lipoxygenase; D011451:Prostaglandin-Endoperoxide Synthases; D007213:Indomethacin