Suppression of oxytocin-induced prostaglandin F2alpha release after intra-uterine nordihydroguariaretic acid administration in ewes.
Intrauterine administration of the 5-lipoxygenase inhibitor nordihydroguariaretic acid (NDGA; 5 mg, bid) on Days 9-14 of the ovine estrous cycle (estrus = Day 0) delayed luteolysis and extended the duration of the estrous cycle (20+/-1, SD, vs. 16+/-1 days; P < 0.01). In control ewes, plasma concentrations of 13,14,dihydro-15-keto prostaglandin F2alpha increased significantly (P < 0.001) following i.v. administration of oxytocin (10 i.u.) on Day 14; in the nordihydroguariaretic acid-treated ewes, however, there was no such increase. In addition, concentrations of endometrial oxytocin receptors were significantly less (P < 0.01) in the nordihydroguariaretic acid-treated ewes (218+/-60 vs. 579+/-66 fmol/mg tissue). These results suggest that 5-lipoxygenase products of arachidonate metabolism may be involved in the control of ovine luteal function.
Cooke
R G
RG
Department of Veterinrary Preclinical Sciences, University of Liverpool, Cheshire, United Kingdom. cooker@liv.ac.uk
Ahmad
N
N
D000818:Animals; D015237:Dinoprost / Q000378:metabolism*; D005260:Female; D009637:Masoprocol / Q000008:administration & dosage / Q000494:pharmacology*; D010121:Oxytocin / Q000037:antagonists & inhibitors*; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D018045:Receptors, Oxytocin / Q000187:drug effects / Q000378:metabolism; D012756:Sheep; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism
D018045:Receptors, Oxytocin; D011374:Progesterone; D010121:Oxytocin; D009637:Masoprocol; D015237:Dinoprost