title: Effects of cortisol on pregnancy rate and corpus luteum function in heifers: an in vivo study.
abstract: To determine whether glucocorticoids affect the function of the bovine corpus luteum (CL) during the estrous cycle and early pregnancy, we examined the effects of exogenous cortisol or reduced endogenous cortisol on the secretion of progesterone (P4) and on pregnancy rate. In preliminary experiments, doses of cortisol and metyrapone (an inhibitor of cortisol synthesis) were established (n=33). Cortisol in effective doses of 10 mg blocked tumor necrosis factor-induced prostaglandin F(2α) secretion as measured by its metabolite (PGFM) concentrations in the blood. Metyrapone in effective doses of 500 mg increased the P4 concentration. Thus, both reagents were then intravaginally applied in the chosen doses daily from Day 15 to 18 after estrus (Day 0) in noninseminated heifers (n=18) or after artificial insemination (n=36). Pregnancy was confirmed by transrectal ultrasonography between Days 28-30 after insemination. Plasma concentrations of P4 were lower in cortisol-treated heifers than in control heifers on Days 17 and 18 of the estrous cycle (P<0.05). However, the interestrus intervals were not different between control and cortisol-treated animals (P>0.05). Moreover, metyrapone increased P4 and prolonged the CL lifespan in comparison to control animals (P<0.05). Interestingly, in inseminated heifers, cortisol increased the pregnancy rate (75%) compared with control animals (58%), whereas metyrapone reduced the pregnancy rate to 16.7% (P<0.05). The overall results suggest that cortisol, depending on the physiological status of heifers (pregnant vs. nonpregnant), modulates CL function by influencing P4 secretion. Cortisol may have a positive influence on CL function during early pregnancy, leading to support of embryo implantation and resulting in higher rates of pregnancy in heifers.
authors.affiliation: Laboratory of Reproductive Physiology, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hai Thanh
authors.initials: HT
authors.lastname: Duong
authors.forename: Katarzyna Karolina
authors.initials: KK
authors.lastname: Piotrowska-Tomala
authors.forename: Tomas Javier
authors.initials: TJ
authors.lastname: Acosta
authors.forename: Mamadou Mousa
authors.initials: MM
authors.lastname: Bah
authors.forename: Emilia
authors.initials: E
authors.lastname: Sinderewicz
authors.forename: Magdalena
authors.initials: M
authors.lastname: Majewska
authors.forename: Katarzynna
authors.initials: K
authors.lastname: Jankowska
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Okuda
authors.forename: Dariusz Jan
authors.initials: DJ
authors.lastname: Skarzynski
mesh_terms: D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000037:antagonists & inhibitors; D000282:Administration, Intravaginal; D000818:Animals; D017849:Animals, Inbred Strains; D000963:Antimetabolites / Q000008:administration & dosage / Q000494:pharmacology; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D003612:Dairying / Q000379:methods; D004305:Dose-Response Relationship, Drug; D010064:Embryo Implantation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005938:Glucocorticoids / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006854:Hydrocortisone / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000662:veterinary; D008797:Metyrapone / Q000008:administration & dosage / Q000494:pharmacology; D011044:Poland; D011247:Pregnancy; D018873:Pregnancy Rate; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D012099:Reproductive Techniques
chemical_list: D000963:Antimetabolites; D004791:Enzyme Inhibitors; D005300:Fertility Agents, Female; D005938:Glucocorticoids; D011374:Progesterone; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D006854:Hydrocortisone; D008797:Metyrapone