Luteotrophic Effect of GNRH Or HCG on Corpus Luteum Functionality During The Luteal Phase in Ewes.

FERNANDEZ J, BRUNO GALARRAGA M, SOTO A, DE LA SOTA L, CUETO M, NOTARO U, SALVETTI N, ORTEGA H, GIBBONS A, LACAU- MENGIDO I.

Mar del Plata. Buenos Aires. Argentina.

Congreso; Reunión anual de sociedades de Biociencias: SAIC, SAFE, SAP, AACYTAL, NANOMED-ar, HCS. 13-16 de noviembre de 2019.; 2019

SAIC

Different therapeutic strategies have been usedwith the objective of increasing the concentration of progesterone (P4) andimproving luteal function in order to reduce embryonic losses. The objective ofthe study was to determine the effect of gonadotrophin releasing hormone (GnRH)or human chorionic gonadotrophin (hCG) treatment at 4 days after timedartificial insemination (TAI) on the induction of accessory corpora lutea(acc-CL), the production and synthesis of P4. A total of 27 adult Merino eweswere randomly assigned to three groups on day 4 post TAI: GnRH group (n= 9; 4 μgIM of GnRH analogue, Receptal®, Intervet, Argentine), hCG group (n= 9; 300 IUIM of hCG, Gonacor®, Ferring, Argentine) and Control group (n= 9; 1 ml IM ofsaline solution). Laparoscopic observations of the ovaries on days 4 and 10post TAI were performed to determine the presence of ovulatory CL (o-CL) andacc-CL, respectively. Serum P4 concentration was assessed by chemiluminescenceon days 4, 7 and 14 post TAI. On day 14 post TAI, o-CL and acc-CL were removed(n= 5 ewes per each treatment) to determine STAR and 3ß-hydroxysteroiddehydrogenase (3ß-HSD) expressions by immunohistochemistry. The results wereanalyzed by ANOVA. The GnRH and hCG treated groups had a higher number ofacc-CL compared to the control group (1.3 ± 0.1 vs. 0.0 ± 0.0, p<0.01). Theadministration of hCG increased serum P4 concentrations on days 7 and 14 postTAI (4.2 ± 0.4, 12.1 ± 1.4 ng/ml) compared to GnRH group (3.1 ± 0.4, 8.5 ± 1.4ng/ml) and the Control group (3.5 ± 0.4, 6.7 ± 1.4 ng/ml; p<0.05). The STARand 3ß-HSD positive cell/area tissue of both o-CL and acc-CL were higher in thehCG group than GnRH and Control groups (p<0.05). In conclusion,administration of hCG or GnRH on day 4 post TAI induced the formation of anacc-CL. However, serum concentration of P4 and some members of the progesteronesynthesis pathway increased significantly only in the hCG group, evidencingdifferent steroidogenic capacity of this hormone.