title: Aglepristone (RU534) administration to non-pregnant bitches in the mid-luteal phase induces early luteal regression.
abstract: The effect of the antiprogestagen aglepristone (10 mg/kg bw), administered at days 29 and 30 following the estimated day of LH surge (day 0), on corpora lutea (CL) function was examined during the diestrus phase of non-pregnant bitches. Aglepristone shortened (P < 0.01) the luteal phase and complete luteolysis (progesterone <2 ng/mL) was observed at days 40.8 +/- 3.5 and 71.5 +/- 4.6 (means +/- SD; n = 9/group) in treated and control bitches, respectively. Peripheral estradiol-17beta concentrations declined from 91.5 +/- 14.3 pg/mL at day 9 to 50 pg/mL at day 18, remaining at approximately the same levels thereafter in both treated and control bitches. Intraluteal in vitro synthesis of progesterone and estradiol-17beta released by CL explanted at day 38 from control bitches (511.9 +/- 285.6 and 40.7 +/- 17.2 pg/mg protein, respectively) did not differ from that of treated. From day 38, intraovarian hemodynamic variables (arterial blood flow, systolic peak, and end-diastolic velocities), monitored by color-coded and pulsed Doppler, decreased more steeply (P < 0.01) in aglepristone-treated (n = 4) than in control (n = 4) bitches, whereas the resistance index increased (P < 0.01) in treated animals. All the blood flow parameters were undetectable at 60 +/- 3.6 and 68 +/- 2.0 days (medians +/- SD) after LH peak in treated and control bitches, respectively. In conclusion, aglepristone administration to dogs during the mid-luteal phase markedly accelerates the luteolytic process which is accompanied by a parallel decline in ovarian blood flow supply with a shift from approximately 8 to 10 days.
authors.affiliation: Dipartimento di Patologia, Clinica e Diagnostica Veterinaria, Sezione di Ostetricia e Ginecologia, Università di Perugia, via S. Costanzo 4, Perugia I-06123, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Polisca
authors.forename: L
authors.initials: L
authors.lastname: Scotti
authors.forename: R
authors.initials: R
authors.lastname: Orlandi
authors.forename: G
authors.initials: G
authors.lastname: Brecchia
authors.forename: M
authors.initials: M
authors.lastname: Maranesi
authors.forename: M
authors.initials: M
authors.lastname: Zerani
authors.forename: C
authors.initials: C
authors.lastname: Boiti
mesh_terms: D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects / Q000378:metabolism; D004285:Dogs / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D004963:Estrenes / Q000009:adverse effects / Q000494:pharmacology*; D005260:Female; D006727:Hormone Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D003341:Luteolysis / Q000187:drug effects*; D010053:Ovary / Q000098:blood supply / Q000000981:diagnostic imaging; D011374:Progesterone / Q000037:antagonists & inhibitors / Q000378:metabolism; D012039:Regional Blood Flow; D014463:Ultrasonography
chemical_list: D004963:Estrenes; D006727:Hormone Antagonists; C419063:aglepristone; D011374:Progesterone; D004958:Estradiol