Hormonal therapeutic strategy on the induction of accessory corpora lutea in relation to follicle size and on the increase of progesterone in sheep.

Autor: Fernandez J; Laboratorio de Reproducción de Rumiantes Menores, INTA Bariloche, San Carlos de Bariloche, Argentina. Electronic address: fernandez.jimena@inta.gob.ar., Bruno-Galarraga MM; Laboratorio de Reproducción de Rumiantes Menores, INTA Bariloche, San Carlos de Bariloche, Argentina., Soto AT; Facultad de Ciencias Veterinarias, Universidad Nacional de la Plata, Argentina., de la Sota RL; Facultad de Ciencias Veterinarias, Universidad Nacional de la Plata, Argentina., Cueto MI; Laboratorio de Reproducción de Rumiantes Menores, INTA Bariloche, San Carlos de Bariloche, Argentina., Lacau IM; Laboratorio de Regulación Hipofisaria, Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina., Gibbons AE; Laboratorio de Reproducción de Rumiantes Menores, INTA Bariloche, San Carlos de Bariloche, Argentina.
Jazyk: angličtina
Zdroj: Theriogenology [Theriogenology] 2018 Jan 01; Vol. 105, pp. 184-188. Date of Electronic Publication: 2017 Sep 23.
DOI: 10.1016/j.theriogenology.2017.09.020
Abstrakt: We determined the effect of GnRH or hCG treatment on day 4 post-time artificial insemination (FTAI) on the formation of accessory corpora lutea (acc-CL) and on the concentration of serum progesterone (P 4 ) in sheep. Multiparous adult Merino ewes (n = 36) were synchronized for estrus using double injection of PGF2α agonist (125 μg Cloprostenol) with an interval of 14 days. At 53-56 h after the second PG application, FTAI was performed. On day 4 post FTAI, ewes were either treated with analogue of GnRH (4 μg buserelin; n = 12) or hCG (300 IU, hCG; n = 12) or saline solution (1 ml; Control; n = 12). Two laparoscopic ovarian examinations were performed on days 4 and 10 post FTAI. In the first observation, we determined the number of post ovulation corpora lutea (po-CL) and the site, number and diameter of follicles present in both ovaries. In the second laparoscopy, we observed the number of po-CL and acc-CL. The sizes of the follicles that generated the acc-CL were determined according to the position of the follicles observed in the first laparoscopy. Serum P 4 concentration was determined on days 4, 7, 10, 13, 17 and 21 post FTAI by chemiluminescence. A similar follicular population in size and number was observed in the three experimental groups prior to the beginning of treatments (Follicles 2 mm: 6.4 ± 3.7, 3 mm: 3.0 ± 2.3, 4 mm: 1.1 ± 0.5, 5 mm: 1.4 ± 0.8; P ˃ 0.05). The formation of 1.0 ± 0.4 and 1.1 ± 0.3 acc-CL was observed in the GnRH and hCG groups, respectively (P ˃ 0.05), but was not observed in the Control group (P < 0.05). Follicle sizes from which acc-CL generated were 3, 4 and 5 mm and did not differ between hormonal treatments (P ˃ 0.05). The hCG group had higher mean concentrations of P 4 on days 7, 10, 13 and 17 post FTAI compared with the GnRH group and the Control group (P < 0.05), while no differences were observed between these two latter groups (P > 0.05). Mean P 4 concentrations in ewes treated with hCG showed no differences according to the size of the follicle from which acc-CL were generated (P ˃ 0.05). In conclusion, administration of hCG or GnRH on day 4 post FTAI induced the formation of one acc-CL from follicles of 3, 4 or 5 mm, indistinctly. However, serum P 4 concentration increased significantly only in the hCG group. The serum P 4 concentrations of acc-CL that originated from different follicle sizes did not differ.
(Copyright © 2017. Published by Elsevier Inc.)
Databáze: MEDLINE
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