title: Development of corpus luteum susceptibility to an analog of prostaglandin F2α, throughout the luteal phase in llamas (Lama glama).
abstract: The aim of the present study was to evaluate the susceptibility of the corpus luteum to d-cloprostenol (synthetic analog of PGF(2α)) throughout the luteal phase in llamas. Female llamas (n=43) were induced to ovulate by GnRH injection in the presence of an ovulatory follicle and randomly assigned into one of six groups: control and treated with an injection of d-cloprostenol on Day 3, 4, 5, 6 or 8 post GnRH. Blood samples were collected to determine plasma progesterone concentrations. There was no effect of treatment on animals injected on Day 3 or 4 post-GnRH. In animals treated on Day 5, different responses were observed. No effect of treatment was recorded in 27% of the animals whereas 55% of the llamas showed a transitory decrease followed by a recovery in plasma progesterone concentrations after d-cloprostenol injection, indicative of a resurgence of the corpus luteum, extending the luteal phase a day more than in control animals. In the remaining 18% of the animals injected on Day 5, (corresponding to those exhibiting the greatest plasma progesterone concentrations at the day of injection), complete luteolysis was observed. Plasma progesterone concentrations decreased to below 1 ng ml(-1) 24 h after d-cloprostenol in llamas injected on Day 6 or 8 post-GnRH. In conclusion, the corpus luteum of llamas is completely refractory to PGF(2α) until Day 4 after induction of ovulation, being partially sensitive by Day 5 and fully responsive to PGF(2α), by Day 6 after induction of ovulation.
authors.affiliation: Área de Endocrinología, Facultad de Ciencias Veterinarias, U.N.C.P.B.A., Campus Universitario, Paraje Arroyo Seco, Buenos Aires, Argentina. cbianchi@vet.unicen.edu.ar
authors.forename: C P
authors.initials: CP
authors.lastname: Bianchi
authors.forename: M V
authors.initials: MV
authors.lastname: Cavilla
authors.forename: E
authors.initials: E
authors.lastname: Jorgensen
authors.forename: M A
authors.initials: MA
authors.lastname: Benavente
authors.forename: M A
authors.initials: MA
authors.lastname: Aba
mesh_terms: D000818:Animals; D002161:Camelids, New World / Q000502:physiology*; D003008:Cloprostenol / Q000494:pharmacology*; D003338:Corpus Luteum / Q000187:drug effects*; D015237:Dinoprost / Q000031:analogs & derivatives*; D005260:Female; D008183:Luteal Phase / Q000502:physiology*; D011374:Progesterone / Q000097:blood
chemical_list: D003008:Cloprostenol; D011374:Progesterone; D015237:Dinoprost