Estrogens Regulate Placental Angiogenesis in Horses

A sufficient vascular network within the feto-maternal interface is necessary for placental function. Several pregnancy abnormalities have been associated with abnormal vascular formations in the placenta. We hypothesized that growth and expansion of the placental vascular network in the equine (Equus caballus) placenta is regulated by estrogens (estrogen family hormones), a hormone with a high circulating concentration during equine gestation. Administration of letrozole, a potent and specific inhibitor of aromatase, during the first trimester (D30 to D118), decreased circulatory estrone sulfate concentrations, increased circulatory testosterone and androstenedione concentrations, and tended to reduce the weight of the fetus (p \u3c 0.1). Moreover, the gene expression of CYP17A1 was increased, and the expression of androgen receptor was decreased in the D120 chorioallantois (CA) of letrozole-treated mares in comparison to that of the control mares. We also found that at D120, the number of vessels tended to decrease in the CAs with letrozole treatment (p = 0.07). In addition, expression of a subset of angiogenic genes, such as ANGPT1, VEGF, and NOS2, were altered in the CAs of letrozole-treated mares. We further demonstrated that 17β-estradiol increases the expression of ANGPT1 and VEGF and increases the angiogenic activity of equine endothelial cells in vitro. Our results from the estrogen-suppressed group demonstrated an impaired placental vascular network, suggesting an estrogen-dependent vasculogenesis in the equine CA during the first trimester

Sustained high progesterone concentrations during estradiol-progesterone based estrus synchronization protocol in Japanese Black cows affects fertility by influencing preovulatory follicle size and its ovulation

Preovulatory follicle (POF) size during estrus synchronization has been reported as one of the factors affecting conception rate in cattle. In present study, to determine the effects of POF size on the fertility of Japanese Black cows, relationship between POF size and conception rates and the effects of progesterone (P4) concentration on POF size were examined. An intravaginal progesterone-releasing device (CIDR) insertion and estradiol benzoate (EB) injection were applied to cows (day 0). At CIDR removal (day 8), the cows were received prostaglandin F2α and subsequently artificially inseminated between days 10 and 11, after EB administration (day 9). The cow that did not ovulate within 3 days after insemination had a small POF (ranging 5 to 8 mm) at CIDR removal, and they did not get pregnant. Cows that ovulated within 3 days were classified based on the POF size as follows: 1) small follicles (SF): POF < 10 mm, 2) medium follicles (MF): 10 ≤ POF < 11 mm, and 3) large follicles (LF): POF ≥ 11 mm. There was no difference in conception rates between SF (78.0%), MF (73.5%) and LF (62.2%). Luteolysis during CIDR treatment occurred in all cows in MF and LF groups, however 39.1% in SF showed no luteolysis. In the cows with non-luteolysis in SF, POF size at CIDR removal was smaller than the luteolysis group in SF, MF and LF groups (P < 0.05). In Japanese Black cows, P4 concentrations during estrus synchronization affects fertility by controlling POF size and its ovulation rate

3次元細胞共培養法を用いたウマ着床期子宮内膜モデルの確立

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ウマ卵管上皮細胞による受精卵認識における特異的発現物質の検索

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Ovulation of the preovulatory follicle originating from the first-wave dominant follicle leads to formation of an active corpus luteum

The objective of our study was to compare the characteristics of the corpus luteum (CL) formed after ovulation of the dominant follicle (DF) of the first follicular wave (W1) and those of the CL formed after ovulation of the DF of the second (induced) follicular wave (W2). Non-lactating Holstein cows were used for this study. In Experiment 1, cows were treated with PGF2α and GnRH on days 6 and 8 (day 0 = day of follicular wave emergence) for W1 (n = 6) and W2 (n = 6), respectively. Dominant follicles were aspirated on day 9 to quantify the amounts of mRNA (VEGF120, VEGF164, FGF-2, StAR, P450-scc and 3β-HSD) in granulosa cells (GC). In Experiment 2, the size and blood flow area of the CL formed after ovulation of the DF in W1 (W1CL; n = 6) and W2 (W2CL; n = 6) (the day of DF ovulation in W1 and W2 was day 10) were evaluated on days 12, 15, 18 and 21. The plasma P4 concentration was measured on days 10 to 21. The amounts of VEGF164, P450-scc and 3β-HSD mRNA were higher (P < 0.05) in the DF in W1, and those of VEGF120,FGF-2 and StAR mRNA tended to be higher (P < 0.1) in the DF in W1. The size of the CL was greater in the W1CL on days 15, 18 and 21. The blood flow area of the CL was greater in the W1CL on days 12 and 15. The plasma P4 concentrations were higher in the W1CL. These results indicate that the CL formed after ovulation of the DF in W1 was greater in terms of size, blood flow and plasma P4 concentration.https://www.jstage.jst.go.jp/article/jrd/61/4/61_2014-099/_article/-char/ja

Effects of a single use of the GnRH analog buserelin on the induction of ovulation and endocrine profiles in heavy draft mares

We observed structural changes in the follicles and uterus of heavy draft mares during estrus and examined the effect of a single injection of the gonadotropin-releasing hormone analog buserelin on ovulation and endocrine profiles. Twenty-two heavy draft mares were divided into a buserelin-treated group (n=8) and a control group (n=14). Mares were given an intramuscular injection of 40 µg buserelin when they presented signs of estrus to a teaser stallion, had ≥45 mm diameter follicles, and presented decreased uterine edema compared with the previous examination. The follicles and uterus were monitored using transrectal ultrasound imaging and measurement of blood levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and estradiol-17β. The ovulation rates within 48 hr was significantly higher in the treated group (100%, 8/8) than in the control group (57.1%, 8/14; P=0.051). The mean ± SEM time before confirmation of ovulation was 29 ± 9 hr for the treated group and 59 ± 7 hr for the control group. There were no significant differences in mating frequency, double ovulation rate, or fertility rate between the two groups. One to two days after administering buserelin, LH and FSH temporarily increased, and in the control group, LH was high during ovulation, whereas FSH temporarily increased with the growth of the follicle. These results indicate that a single injection of 40 µg buserelin when follicles are at least 45 mm in diameter and uterine edema is decreased is effective for inducing ovulation.https://www.jstage.jst.go.jp/article/jes/27/4/27_1615/_article/-char/ja