Does injection of prostaglandin F2α (PGF2α) cause ovulation in anestrous Western White Face ewes?
| Autor: | D.M.W. Barrett, E.T. Bagu, Rajesha Duggavathi, K.L. Davies, Pawel M. Bartlewski, S.J. Cook, N.C. Rawlings, T. Epp |
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| Rok vydání: | 2006 |
| Předmět: |
Ovulation
medicine.medical_specialty media_common.quotation_subject medicine.medical_treatment Luteolysis Alpha (ethology) Ovary Medroxyprogesterone Acetate Dinoprost Injections Intramuscular Anestrus Andrology Random Allocation Ovarian Follicle Ovulation Induction Food Animals Internal medicine Contraceptive Agents Female medicine Animals Medroxyprogesterone acetate Small Animals Saline Progesterone media_common Drug Implants Estrous cycle Sheep Equine Chemistry Luteinizing Hormone Endocrinology medicine.anatomical_structure Female Animal Science and Zoology Blood sampling medicine.drug |
| Zdroj: | Theriogenology. 66:251-259 |
| ISSN: | 0093-691X |
| Popis: | In a previous study in our laboratory, treatment of non-prolific Western White Face (WWF) ewes with PGF(2 alpha) and intravaginal sponges containing medroxyprogesterone acetate (MAP) on approximately Day 8 of a cycle (Day 0 = first ovulation of the interovulatory interval) resulted in ovulations during the subsequent 6 days when MAP sponges were in place. Two experiments were performed on WWF ewes during anestrus to allow us to independently examine if such ovulations were due to the direct effects of PGF(2 alpha) on the ovary or to the effects of a rapid decrease in serum concentrations of progesterone at PGF(2 alpha)-induced luteolysis. Experiment 1: ewes fitted with MAP sponges for 6 days (n = 12) were injected with PGF(2 alpha) (n = 6; 15 mg im), or saline (n = 6) on the day of sponge insertion. Experiment 2: ewes received progesterone-releasing subcutaneous implants (n = 6) or empty implants (n = 5) for 5 days. Six hours prior to implant removal, all ewes received a MAP sponge, which remained in place for 6 days. Ewes from both experiments underwent ovarian ultrasonography and blood sampling once daily for 6 days before and twice daily for 6 days after sponge insertion. Additional blood samples were collected every 4 h during sponge treatment. Experiment 1: 4-6 (67%) PGF(2 alpha)-treated ewes ovulated approximately 1.5 days after PGF(2 alpha) injection; these ovulations were not preceded by estrus or a preovulatory surge release of LH, and resulted in transient corpora hemorrhagica (CH). The growth phase was longer (P < 0.05) and the growth rate slower (P < 0.05) in ovulating versus non-ovulating follicles in PGF(2 alpha)-treated ewes. Experiment 2: in ewes given progesterone implants, serum progesterone concentrations reached a peak (1.7 2 ng/mL; P < 0.001) on the day of implant removal and decreased to basal concentrations ( |
| Databáze: | OpenAIRE |
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