Prostaglandin E(2) 9-keto reductase activity in bovine retained and not retained placenta

The Effects of Prostaglandin E2 Treatment on the Secretory Function of Mare Corpus Luteum Depends on the Site of Application: An in vivo Study

We examined the effect of prostaglandin (PG) E₂ on the secretory function of equine corpus luteum (CL), according to the application site: intra-CL injection vs. an intrauterine (intra-U) administration. Moreover, the effect of intra-CL injection vs. intra-U administration of both luteotropic factors: PGE₂ and human chorionic gonadotropin (hCG) as a positive control, on CL function was additionally compared. Mares were assigned to the groups (n = 6 per group): (1) an intra-CL saline injection (control); (2) an intra-CL injection of PGE₂ (5 mg/ml); (3) an intra-CL injection of hCG (1,500 IU/ml); (4) an intra-U saline administration (control); (5) an intra-U administration of PGE₂ (5 mg/5 ml); (6) an intra-U administration of hCG (1,500 IU/5 ml). Progesterone (P₄) and PGE₂ concentrations were measured in blood plasma samples collected at −2, −1, and 0 (pre-treatment), and at 1, 2, 3, 4, 6, 8, 10, 12, and 24 h after treatments. Moreover, effects of different doses of PGE₂ application on the concentration of total PGF_2α (PGF_2α and its main metabolite 13,14-dihydro-15-keto-prostaglandin F_2α– PGFM) was determined. The time point of PGE₂, hCG, or saline administration was defined as hour “0” of the experiment. An intra-CL injection of PGE₂ increased P₄ and PGE₂ concentrations between 3 and 4 h or at 3 and 12 h, respectively (p < 0.05). While intra-U administration of PGE₂ elevated P₄ concentrations between 8 and 24 h, PGE₂ was upregulated at 1 h and between 3 and 4 h (p < 0.05). An intra-CL injection of hCG increased P₄ concentrations at 1, 6, and 12 h (p < 0.05), while its intra-U administration enhanced P₄ and PGE₂ concentrations between 1 and 12 h or at 3 h and between 6 and 10 h, respectively (p < 0.05). An application of PGE₂, dependently on the dose, supports equine CL function, regardless of the application site, consequently leading to differences in both P₄ and PGE₂ concentrations in blood plasma.

Expression profile of proinflammatory mediators in the placenta of mares during physiological detachment and retention of fetal membranes

Physiological parturition is characterized by sterile, inflammatory-like processes. During parturition, the placenta expresses various proinflammatory mediators, such as chemokines and IL-17. Nevertheless, inflammatory processes present in the parturient mare are poorly characterized. The aim of this study was to investigate the expression of selected chemokines and IL-17 in the allantochorion and the endometrium of mares that retained fetal membranes (RFM) and expelled them physiologically. We hypothesized that the expression of these mediators may be altered in the placenta of mares with RFM and result in RFM occurrence. Differences in mRNA expression in the placenta of investigated groups of mares were detected for CCL2, CCL3, CCL4, CCL8, CXCL1, CXCL8, CXCL10, CX3CL1 and IL-17. There were no differences in mRNA expression of CCL5 and CXCL6. Gene ontology network analysis showed enrichment in genes related to leukocyte migration, cell chemotaxis and response to chemokine in tissues of RFM mares. Analysis of association network suggested denotations between CXCL6, CXCL8, CXCL1, CCL5, CCL4, CX3CL1 and CXCL10. Moreover, possible inhibition of CXCL10 by IL-17A and prostaglandin peroxide synthase 2 (PTGS2) by CXCL1 was detected. Our results suggest that, based on differences in chemokines and IL-17 expression, recruited subsets of leukocytes might differ between the analyzed groups of mares, which in turn may impair the separation of fetal membranes in the group of RFM mares. In addition, the results of the expression analysis suggest that macrophages might be one of the most abundant cells infiltrating the equine placenta during the expulsion of fetal membranes. Furthermore, we suspect that the synthesis of PTGS2 might be inhibited in mares with RFM.

The preliminary studies on protein profile in retained and not retained foetal membranes in heavy draft mares

Protein profile of the placenta expresses its function and maintenance. Any alterations can be reflected in qualitative and quantitative changes in this profile. The aim of the present study was the evaluation of protein profile in the placenta of mares suffering from the retention of foetal membranes (FMR) by two separation methods and the comparison with physiologically released tissues. Placentas from 14 healthy, heavy draft mares were collected immediately after the expulsion of newborn. Tissues after homogenization and staining with fluorescent dyes were subjected to electrophoretic as well as chromatographic separation. Electrophoretic gels were statistically analysed for the presence and abundance of examined proteins, while some proteins were identified in chromatographic fractions. Out of 248 spots detected in endometrium, 38 differed significantly between FMR and control animals, while in allantochorion, respective values reached 241 and 27 spots (p < .05). Among identified proteins that expressed higher abundance in endometrium of FMR mares than control animals were prostaglandin reductase, dehydrogenase/reductase SDR family, and placental growth factor. These proteins are involved in regulation of parturition. Additionally, the following proteins responsible for physiological activity of a cell-guanine methyl transferase, aspartyl/asparaginyl beta-hydroxylase and GTP-binding protein, were identified. These proteins expressed higher abundance in allantochorion of FMR mares than in controls. This preliminary study confirmed the disturbances in protein pattern between foetal membranes in FMR and healthy mares. Further qualitative and quantitative experiments are necessary to deepen our knowledge on the mechanisms of the retention of foetal membranes in mares.

Peri-ovulatory endocrine regulation of the prostanoid pathways in the bovine uterus at early dioestrus

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n = 15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P < 0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P < 0.05) and phospholipase A2 was downregulated (P < 0.05) in endometrium of the LF-LCL group. No difference (P > 0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P < 0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.

Dietary n-3 polyunsaturated fatty acids alter the expression of genes involved in prostaglandin biosynthesis in the bovine uterus

Nutrition plays a critical role in the regulation of cow fertility. There is emerging evidence that dietary long chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) may act as specific regulators of some reproductive processes. In vitro studies suggest that the n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may play pivotal roles by suppressing the synthesis of uterine prostaglandin F(2alpha) (PGF(2alpha)) which is centrally involved in the control of the bovine oestrous cycle and in early embryo survival. The objective of the current study was to determine the effect of dietary inclusion of n-3 PUFA on uterine endometrial mRNA expression of key genes regulating PGF(2alpha) biosynthesis. Beef heifers were fed either a low (CON; n=10) or high (HIGH PUFA; n=10) n-3 PUFA diet for 45 days and endometrial tissues were harvested following slaughter. Following analysis, tissues within each dietary group were ranked on the basis of their PUFA concentrations and the highest (n=7) and lowest (n=7) within each of HIGH PUFA and CON, respectively, were used in gene expression studies. Endometrial n-3 PUFA concentrations were more than two-fold higher (P<0.05) and EPA concentrations alone more than seven-fold higher (P<0.01) in the HIGH PUFA than the CON group. Endometrial concentrations of arachidonic acid, were lower (P<0.001) in the tissues from HIGH PUFA than those from the CON group. Total RNA was isolated from all endometrial tissues and real-time reverse transcription (RT) PCR conducted to compare the relative expression of 11 genes with known involvement in uterine biosynthesis of 2-series prostaglandins. Expression of mRNA for prostaglandin E synthase (PGES) and peroxisome proliferator-activated receptors, PPAR alpha and delta was increased (P<0.05) while mRNA expression of phospholipase A(2) (PLA(2)) was decreased (P=0.06) in the HIGH PUFA endometrial tissues. Expression of genes coding for the oxytocin receptor (OTR), phospholipase C (PLC), cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), PGE(2) 9-ketoreductase (9-KPR), prostaglandin F synthase (PGFS), and the nuclear transcription factor, PPAR gamma was not different (P>0.05) between HIGH PUFA and CON tissues. Overall the results indicate that key genes regulating uterine PGF(2alpha) biosynthesis can be regulated by dietary inclusion of LC n-3 PUFA which may influence uterine function and embryo survival.

Detrimental effects of prostaglandin F2α on preimplantation bovine embryos

Two studies were performed to determine effects of prostaglandin F2alpha (PGF2alpha) on continued development of pre-compacted (in vitro-produced) and compacted (in vivo-derived) bovine embryos. In Experiment 1, pre-compacted embryos were placed in KSOM media supplemented with polyvinyl alcohol (0.3%) and assigned to the following treatments: (1) control; (2) PGF-1 (1 ng/mL PGF2alpha); (3) PGF-10 (10 ng/mL PGF2alpha); (4) PGF-100 (l00 ng/mL PGF2alpha); or (5) PGE-5 (5 ng/mL PGE2). Following 4 days of incubation in assigned treatments, continued development of pre-compacted embryos to blastocysts was reduced by addition of PGF2alpha in culture medium (P = 0.002). Development did not differ between control and PGE2 treatments (P > 0.10). In Experiment 2, compacted morula' s were placed in KSOM-PVA supplemented media and assigned to one of four treatments: (1) control; (2) PGF-0.1 (0.1 ng/mL PGF2alpha); (3) PGF-1 (1 ng/mL PGF2alpha); and (4) PGF-10 (10 ng/mL PGF2alpha). After 24h in culture, embryos were washed and placed in KSOM-BSA (0.5%) without PGF2alpha for an additional 48 h until assessment for development. Continued development of compacted morula to blastocyst was not affected by addition of PGF2alpha to the culture medium (P > 0.10). However, hatching rates of embryos cultured with PGF2alpha were lower (P = 0.05). In conclusion, it is suggested that PGF2alpha has a direct negative effect on continued embryonic development of pre-compacted and compacted bovine embryos.

Poly(ADP-ribose) polymerase in bovine retained and not retained placenta

Poly(ADP-ribose) polymerase (PARP) synthesizes poly(ADP-ribose) in response to DNA strand breaks using NAD+ as a substrate. It leads to consequences for metabolism not only on a cellular level, but also on a tissue level, among others: NAD+ and ATP depletion. Retention of foetal membranes (RF) in cows is supposed to be connected with the imbalance between production and neutralization of reactive oxygen species, leading to oxidative damage to DNA, lipids and proteins. The aim of this preliminary study was to detect the presence of PARP in bovine placenta and to describe the enzyme with respect to type of placental tissue, time and mode of delivery. Placentomes, collected after spontaneous delivery or caesarian section, were divided into maternal and foetal parts of placenta, homogenized, and subjected to electrophoresis. Cows were divided into six groups as follows: (A) caesarian section before term with RF, (B) caesarian section before term without RF, (C) spontaneous delivery at term with RF, (D) spontaneous delivery at term without RF, (E) caesarian section at term with RF, (F) caesarian section at term without RF. PARP was detected by Western blotting using commercially available bovine anti PARP antibody. Bands referred to as bovine PARP standard were present in all examined tissues as well as the products of its cleavage. However, the patterns of bands were different with respect to type of tissue, time, and mode of delivery. Further experiments on detailed relationship between PARP activity and the process of releasing and retaining of bovine placenta are necessary.

Is poly(ADP-ribose) polymerase involved in bovine placental retention?

Poly(ADP-ribose) polymerase (PARP) is the enzyme which utilises NAD to synthesise poly(ADP-ribose) polymers. This process appears in response to DNA lesions. Oxidative stress, which might be involved in bovine placental retention, is the reason for oxidative DNA injury. In this mini-review, the relationship between PARP activity and bovine placental retention is discussed. The results of our experiments on PARP activity in placental tissues showed that the enzyme of 113 kDa and its cleavage products were present in retained as well as released fetal membranes. Western blotting technique showed different intensities in the staining of bands which might suggest different activities of the enzyme.