Maternal recognition of pregnancy in the horse : are MicroRNAs the secret messengers?

The signal for maternal recognition of pregnancy (MRP) has still not been identified in the horse. High-throughput molecular biology at the embryo-maternal interface has substantially contributed to the knowledge on pathways affected during MRP, but an integrated study in which proteomics, transcriptomics and miRNA expression can be linked directly is currently lacking. The aim of this study was to provide such analysis. Endometrial biopsies, uterine fluid, embryonic tissues, and yolk sac fluid were collected 13 days after ovulation during pregnant and control cycles from the same mares. Micro-RNA-Sequencing was performed on all collected samples, mRNA-Sequencing on the same tissue samples and mass spectrometry was conducted previously on the same fluid samples. Differential expression of miRNA, mRNA and proteins showed high conformity with literature and confirmed involvement in pregnancy establishment, embryo quality, steroid synthesis and prostaglandin regulation, but the link between differential miRNAs and their targets was limited and did not indicate the identity of an unequivocal signal for MRP in the horse. Differential expression at the embryo-maternal interface was prominent, highlighting a potential role of miRNAs in embryo-maternal communication during early pregnancy in the horse. These data provide a strong basis for future targeted studies

Placental characteristics in American minihorses

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Ascending placentitis in the mare

Ascending placentitis in the mare, which affects 3 to 7% of pregnancies, is a common cause of abortion, premature birth and delivery of compromised foals (Troedsson, 2003; LeBlanc, 2010). Since the infection ascends from the caudal genital tract, the first and most distinct lesions are seen near the caudal pole area of the allantochorion adjacent to the cervix. The symptoms are not always obvious or will be exhibited only at a later stage of the disease process, which renders timely adequate treatment difficult. Moreover, experimental models of placentitis in the mare are difficult to maintain and double-blind, controlled studies are scarce, making it hard to formulate clear science-based advice. In this paper, the diagnosis is discussed on the basis of the symptoms, the ultrasound examinations and the endocrinological parameters, and the therapeutic and prognostic considerations are evaluated

Anti-Müllerian Hormone and OPU-ICSI Outcome in the Mare

Simple Summary The in vitro production of equine embryos, using ovum pick-up (OPU) and intracytoplasmic sperm injection (ICSI), is gaining popularity for breeding sport horses. However, the results of this complicated procedure are variable and hard to predict. Therefore, the aim of this study was to evaluate anti-Mullerian hormone (AMH), a factor which has been linked to reproductive success in human and cattle, as an indicator of the OPU-ICSI outcome in horses. Therefore, for 103 mares subjected to commercial OPU-ICSI, the AMH level was measured in the blood at the moment of OPU and linked to the number of oocytes and embryos produced by ICSI. We found that mares with a high level of AMH gave rise to a better oocyte collection and a higher number of embryos. However, since mares with a low AMH value could also produce embryos, a single measurement of the AMH in the blood is not sufficient as an independent predictor of the OPU-ICSI outcome in the horse. Anti-Mullerian hormone (AMH) reflects the population of growing follicles and has been related to mammalian fertility. In the horse, clinical application of ovum pick-up and intracytoplasmic sperm injection (OPU-ICSI) is increasing, but results depend largely on the individuality of the mare. The aim of this study was to assess AMH as a predictor for the OPU-ICSI outcome in horses. Therefore, 103 mares with a total follicle count above 10 were included in a commercial OPU-ICSI session and serum AMH was determined using ELISA. Overall, the AMH level was significantly correlated with the number of aspirated follicles and the number of recovered oocytes (p = 2.5 mu g/L) yielded significantly greater numbers of follicles (22.9 +/- 1.2), oocytes (13.5 +/- 0.8), and blastocysts (2.1 +/- 0.4) per OPU-ICSI session compared to mares with medium (1.5-2.5 mu g/L) or low AMH levels (<1.5 mu g/L), but no significant differences in blastocyst rates were observed. Yet, AMH levels were variable and 58% of the mares with low AMH also produced an embryo. In conclusion, measurement of serum AMH can be used to identify mares with higher chances of producing multiple in vitro embryos, but not as an independent predictor of successful OPU-ICSI in horses

Oxidative stress in donor mares for ovum pick-up delays embryonic development

Abstract: The in vitro production of equine embryos via ovum pick-up (OPU) and intracytoplasmic sperm injection (ICSI) has increased rapidly. There is a marked effect of the individual mare on the outcome of OPU-ICSI, but little is known about the influence of the mare's health condition. This study aimed to investigate the potential associations between the concentrations of interleukin-6 (IL-6), reactive oxygen metabolites (d-ROMs), and biological antioxidant potential (BAP) in serum of oocytes' donor mares and the subsequent embryonic development. Just before OPU, a blood sample was collected from 28 Warmblood donor mares, that were subjected to a routine OPU-ICSI program. The serum concentrations of IL-6, d-ROMs, and BAP were assayed photometrically. The maturation, cleavage and blastocyst rate as well as the kinetics of blastocyst development were recorded. The average blastocyst rate was 24.68 +/- 5.16% and the average concentrations of IL-6, d-ROMs, and BAP were 519.59 +/- 157.08 pg/mL, 171.30 +/- 4.55 carratelli units (UCARR), and 2711.30 +/- 4.55 mu mol/L, respectively. Serum concentrations of IL-6, d-ROMs, and BAP were not significantly different between mares yielding at least one blastocyst (552.68 +/- 235.18 pg/mL, 168.36 +/- 5.56 UCARR, and 2524.80 +/- 159.55 mu mol/L) and mares yielding no blastocysts (468.47 +/- 179.99 pg/mL, 175.85 +/- 7.89 UCARR, and 2999.50 +/- 300.13 mu mol/L, respectively). Serum concentrations of d-ROMs were significantly lower in mares with fast growing (at day 7-8 post ICSI; 148.10 +/- 8.13 UCARR) compared to those with slow growing blastocysts (>= day 9 post ICSI; 179.41 +/- 4.89 UCARR; P = 0.003). Taken together, the serum concentration of IL-6, d-ROMs, and BAP do not determine the mare's ability to produce blastocysts in vitro. Although it may be questioned whether a single sample is representative of the mare's health status, changes in serum metabolites related to oxidative stress at the time of oocyte retrieval were linked to a delayed blastocyst development in a clinical OPU-ICSI outcome