Relationship between bovine endometrial thickness and plasma progesterone and estradiol concentrations in natural and induced estrus

Abstract

The objective of this study was to investigate cyclical changes in endometrial thickness in relation to progesterone (P4) and estradiol-17β (E2) concentrations during natural and induced estrus in 15 cows. In the prostaglandin (PG) F2α-induced estrus group, ultrasonography (USG) at 6-h intervals was used to determine endometrial thickness 48–24 h before the PGF2α treatment until 24 h after ovulation (ovulation = Day 0). In the natural estrus group, USG was performed every 48 h from Day 3 to Days 15–18 after the first ovulation, and then every 6 h until 24 h after ovulation. Endometrial thickness was standardized using Day 13 as a reference day. Blood was collected during every USG examination and plasma P4 and E2 concentrations were determined. Endometrial thickness of the induced estrus group (n = 11) was greater than that of the natural estrus group (n = 9) between 60 and 12 h before ovulation (P < 0.05). In the natural estrus group, prior to an increase in endometrial thickness, a decrease in P4 and an increase in E2 were detected. In the induced estrus group, based on the time of ovulation, an increase in endometrial thickness was detected at the same time of a decrease in P4 before an increase in E2. These results suggest that decreases in P4 concentrations may be a cue to changes in endometrial thickness, while increases in E2 concentrations appear to sustain and/or enhance these changes.

Interactions of circulating estradiol and progesterone on pituitary responsiveness to GnRH and changes in endometrial area

“…Any potential differences in timing or magnitude of the increase in EA are likely to be explained by differences in ultrasound quality and experimental model. A recent study compared the endometrial changes under natural and induced proestrus and reported a more rapid increase in endometrium size in the induced than in the natural proestrus [29]. Our results appeared to be more similar to the natural proestrus, with a gradual and constant increase in the size of the endometrium during a 48 h period rather than the rapid increase followed by a plateau that has been reported during an induced proestrus [13,29].…”

Characterization of the Endometrial Transcriptome in Early Diestrus Influencing Pregnancy Establishment in Dairy Cattle after Transfer of In-Vitro Produced Embryos

“…Results from these studies highly contribute to the knowledge of the endometrial transcriptomic profile at the time when an embryo is transferred into a recipient. However, they also demonstrate that the endometrial transcriptome is affected by many factors, including parity (heifers or cows), breeds (dualpurpose, beef or dairy breed), and induction of estrus 17 .…”

“…During diestrus, the endometrial stroma is thickened and uterine glands enlarged, resulting in an increased production of histotroph 14,15 that is absorbed by the trophoblast of the potential embryo 16 . The thickness of the endometrium depends on the concentration of circulating estradiol and progesterone, and it has been shown to vary between natural or induced estrous 17 .…”

“…Regarding endometrial receptivity, experiments performed in Nellore cows and Simmental heifers 19,21,22 , after estrus synchronization, have unveiled important differences in the endometrial transcriptome at day 6 or 7 of animals that become pregnant after AI or embryo transfer (ET), respectively, compared to the non-pregnant ones. However, disparities in embryo survival between heifers and lactating cows 2 , the different effects of progesterone on the fertility of dairy and beef cows 23 and the variations in hormonal concentration and uterine thickness between induced or natural estrus 17 , indicate the need of further studies for a better comprehension of the mechanisms controlling endometrial receptivity.…”

Research of postpartum endometritis in Japanese Black cattle with cystic ovarian disease by vaginal mucus test and endometrial cytology

“…Ovulation is an important factor for the incidence of COD, and endometritis is associated with failure of ovulation (Opsomer et al, 2000;Sheldon et al, 2002). Escherichia coli is one of the major pathogens of endometritis in dairy cattle (Sheldon et al, 2002;Williams et al, 2005;Westermann et al, 2010;Sun et al, 2011). Uterine infection by E. coli increased lipopolysaccharides (LPS) in ovarian follicles (Herath et al, 2007), which causes dysfunction of the ovulation mechanism and responsiveness for steroid hormone (Polat et al, 2015).…”