Interleukin-1 receptor antagonist expression in the equine endometrium during the peri-implantation period

Production of Calcium Maintenance Factor Stanniocalcin-1 (STC1) by the Equine Endometrium During the Early Pregnant Period

“…A high E2 accumulation in the endometrial region where conceptus fixation occurs could not be achieved via systemic low E2 concentrations. However, endometrial accumulation of E2 could be supported by the observation that the E2 contents are extremely high in the conceptus, significant E2 source at this time of pregnancy [24] that diffuses into the region of the endometrium adjacent to the conceptus.The patterns of the endometrial E2 distribution relative to the region where the conceptus was lodged are suggestive of the STC1 gene being regulated by conceptus E2 and/or maternal progesterone. In the studies by Song et al [29,30], endometrial STC1 was induced by long-term progesterone therapy in ovariectomized ewes and pigs, respectively.…”

“…6). The dose of progesterone (10 ng/ml) was chosen from steroid hormone concentrations detected in serum and endometrial extracts [24]. Under our assay conditions, expression of STC1 mRNA appeared not to be affected or regulated by any steroid treatment.…”

“…Quite recently, the presence of endometrial STC1 in pregnant mares was reported [45]. Although receptors possibly located on the conceptus or functions of endometrial STC1 have not been established in the mare, STC1 could have a role in regulating embryonic calcium and/or phosphorus concentrations at a time in which the conceptus is not supported by a functional placenta.The concentration of equine embryonic E2 on days 16-18 of pregnancy, when fixation of the conceptus occurs, is as high as that on day 25 [24,46]. Considering the observation that a sudden and spasm-like increase in myometrial tone causes fixation of the conceptus at the base of one or the other uterine horn [2,47], a high concentration of embryonic E2 could locally upregulate OXTR levels by activating the estrogen receptor (ER) in a paracrine manner [48].…”

“…Fig. 1) as follows: uterine body (B1, B2, and B3, which is next to the uterine horn), nongravid uterine horn (N1-N3) and gravid uterine horn (G1-G3), of which N1 or G1 was closest to the ovary and N3 or G3 was next to the uterine body [24]. In the day 13 cyclic and pregnant endometrium, uterine horns were designated into right (R1-R3) and left (L1-L3) sides.…”

“…Real-time PCR was utilized to quantify targeted cDNAs using an ABI PRISM 7900HT system (Applied Biosystems) [26]. Oligonucleotide primers were designed through the assistance of the web-based Primer3 software, as previously described [24], and are listed in Table 1. PCR reactions were carried out using Ex Taq Hot Start Version containing SYBR-Green I (Takara Bio), and levels of each target mRNA relative to ACTB mRNA were determined using the 2 -ΔCT method.…”