Altrenogest during early pregnancy modulates uterine glandular epithelium and endometrial growth factor expression at the time implantation in pigs

Abstract

This study evaluated the effects of supplying altrenogest from day 6-12 of pregnancy on the endometrial glandular epithelium, corpora lutea (CL) morphology, and endometrial and CL gene expression. A total of 12 crossbred females (Landrace × Large White) were used. The females were assigned to 4 treatments according to a random design with a 2 × 2 factorial arrangement, with two categories (sow or gilt) and two treatments (non-treated and treated with altrenogest). On day 6 of pregnancy, animals were allocated to one of the following groups: non-treated (NT, n = 6; 3 sows and 3 gilts), and (T, n = 6; 3 sows and 3 gilts) treated daily with 20 mg of altrenogest, from day 6-12 of pregnancy. All animals were euthanized on day 13 of pregnancy. All CLs were individually weighed, and their volume were determined. The endometrial glandular density (GD), mean glandular area (MGA), and vascular density (VD) were determined by histomorphometric and immunohistochemical analyses. Endometrium samples were collected and analyzed by qRT-PCR to evaluate the abundance of transcripts for VEGF and IGF-I. Females in the T group had higher MGA (P < 0.05) compared to the NT group. There was no effect of treatment on GD or VD for both experimental groups. Sows in the T group had augmented expression of IGF-I (P < 0.05). Progestagen had no detrimental effect on CL morphology. In conclusion, altrenogest improves the uterine environment during the peri-implantation period in pigs without compromising corpora lutea development.

Altrenogest Supplementation during Early Pregnancy Improves Reproductive Outcome in Pigs

“…Gilts supplemented with progesterone on days 3–4 of pregnancy (25 mg/100 kg) and 5–10 of pregnancy (50 mg/100 kg) had increased uterine weight, total uterine protein content and increased expression of vascular endothelial growth factor (VEGF) in the endometrium by day 12 of gestation [ 25 ]. Additionally, sows treated daily with 20 mg of altrenogest from days 6–12 of pregnancy had a higher endometrial expression of insulin-like growth factor I (IGF-I) by day 13 of pregnancy [ 38 ]. Among these molecules, IGF-1 influences conceptus growth and endometrial architecture [ 22 ], and it is positively related to fetal weight [ 39 ].…”

“…In agreement with our findings, Fix et al [ 42 ] observed that as birth weight increased, the likelihood of pigs being born alive also increased, which is in agreement with other authors [ 40 , 43 ]. The altrenogest supplementation may have led to improved early conceptus development and, consequently, a lower percentage of piglets born under 800 g [ 25 , 38 ]. One of the leading causes of stillbirths in pigs is asphyxia during parturition [ 42 , 44 ].…”

Estrus Synchronization of Replacement Gilts Using Estradiol Cipionate and PGF2α and Its Effects on Reproductive Outcomes

“…In the present experiment, CYP gilts had increased mean glandular area compared to CON gilts. Studies have already shown that the increase in the area of uterine glands was accompanied by increased expression of IGF-I, VEGF, and increased weight of embryos collected on day 28 of gestation [ 23 , 35 ]. Nevertheless, in our study, the increase in the mean glandular area was not accompanied by changes in embryonic development, possibly because of the stage of embryo development in which the embryos were collected.…”

The neuroendocrine pathways and mechanisms for the control of the reproduction in female pigs

“…By binding to specific receptors (gonadotropin-releasing hormone receptors, GnRHRs) on pituitary gonadotropin cells, GnRH stimulates the biosynthesis and the release of two gonadotropins (luteinizing hormone, LH; follicle-stimulating hormone, FSH). LH and FSH, which are required for the development and maintenance of the gonads and thus for fertility, bind to receptors on the gonads to regulate gametogenesis and gonadal steroidogenesis in both sexes ( Millar 2005 ; Muro et al, 2021 ).…”