Effect of Oestrus Synchronization with PGF2α/eCG/hCG on Luteal P4 Synthesis in Early Pregnant Gilts

Abstract

Administration of hormones to synchronize oestrus is a useful tool in animal breeding. However, exogenous ovarian stimulation may be detrimental to reproductive function. This study was aimed to examine whether an oestrus synchronization with PGF2α/eCG/hCG could affect luteal P4 synthesis in early pregnant gilts. Corpora lutea (CLs) were collected on days 9, 12 and 16 of pregnancy from gilts with natural (n = 16) and synchronized (n = 18) oestrus and analysed for (i) the expre-ssion of steroidogenic acute regulatory protein (StAR), cytochrome P450 family 11 subfamily A polypeptide (CYP11A1), and 3β-hydroxysteroid dehydrogenase (3βHSD); (ii) the concentration of P4 in the luteal tissue and blood; and (iii) the expression of luteinizing hormone receptors (LHR) and oestrogen receptors (ERα and ERβ). Additionally, the effect of LH on P4 secretion from CL slices collected from synchronized and naturally ovulated animals has been studied in vitro. PGF2α /eCG/hCG administration increased mRNA expression of StAR, CYP11A1, 3βHSD, and LHR on day 9 and CYP11A1 and LHR on day 12 of pregnancy compared with the control group (p < 0.05). CYP11A1, 3βHSD, LHR, ERα and ERβ proteins were not affected by synchronization; only StAR protein increased in hormonally treated animals (p = 0.017). The concentration of P4 in luteal tissue was greater on day 9 (p < 0.01), but lower on day 16 (p < 0.05) in gilts with hormonally induced oestrus compared with control animals. Blood serum levels of P4 were lower in synchronized than control gilts (p < 0.001). Synchronization did not affect LH-stimulated P4 secretion from luteal slices; however, greater basal concentration of P4 in incubation medium was detected for CLs collected from synchronized than control gilts (p < 0.05). In conclusion, synchronization of oestrus with PGF2α/eCG/hCG protocol in gilts did not impair the expression of luteal P4 synthesis system, although decreased P4 concentration in the blood.

Changes in Porcine Corpus Luteum Proteome Associated with Development, Maintenance, Regression, and Rescue during Estrous Cycle and Early Pregnancy

“…While we acknowledge that procedures such as estrus induction can probably effect molecular changes, estrus synchronization does not lead to any significant change in luteal steroidogenesis in pigs [ 77 ]. Additionally, though 2D proteomics has its limitations in identifying less abundant and low-molecular-weight proteins, our study resulted in identification of many proteins relevant to luteal function or regression.…”

The effectiveness of natural and gonadotropin stimulation of young gilts

“…The effect of hCG and eCG were tested not only for the induction of sexual maturity in gilts and the synchronization of estrus, but also the influence of these hormones on the function of the corpora lutea (CL) and the fallopian tubes. Szymańska et al (2014) indicate that in gilts the injection of PGF2α/eCG/hCG does not impair the function of the CL, which are the key components of the enzyme and the receptor for synthesis of P4. However, there was a lower concentration of P4 in the serum of animals synchronized, which may reflect some irregularities in the metabolism or secretion of P4.…”