Effect of Nordihydroguaiaretic Acid on Luteal Phase Length and Oxytocin-Induced Release of Prostaglandin F₂ in Heifers

¹ University of Missouri, Columbia 65211

Two experiments were conducted to determine if intrauterine infusion of nordihydroguaiaretic acid, a lipoxygenase pathway inhibitor, would delay luteolysis (Experiment 1) and inhibit oxytocin-induced release of prostaglandin F₂ (as measured by the stable prostaglandin F₂ metabolite, 15-keto-13,14-dihydroprostaglandin F₂) in plasma on d 16 (d 0 = estrus) of the estrous cycle (Experiment 2). Nordihydroguaiaretic acid (20 mg) or saline was infused twice daily into the uterus on d 14 to 23 (Experiment 1) or d 14 to 20 (Experiment 2) postestrus, respectively. In Experiment 1 and 2, mean concentration of progesterone was higher and luteolysis was delayed in nordihydroguaiaretic acid-infused heifers compared with saline-infused heifers. In Experiment 2, saline or oxytocin (100 IU, i.v.) was injected into each heifer on d 16 postestrus to stimulate the release of prostaglandin F₂ from the uterus. Mean concentration of 15-keto-13,14-dihydroprostaglandin F₂ increased within 1.5 h postinjection in heifers infused with saline, whereas concentration of 15-keto-13,14-dihydroprostaglandin F₂ in nordihydroguaiaretic acid-infused heifers did not increase within the same time period. Thus, nordihydroguaiaretic acid may inhibit both the lipoxygenase and cyclooxygenase pathways of arachidonic acid metabolism and therefore delay luteolysis.

Key Words: nordihydroguaiaretic acid • prostaglandin F₂ • corpus luteum

Submitted on November 24, 1989
Accepted on May 14, 1990