Meloxicam administration in the management of postoperative pain and inflammation associated with caesarean section in beef heifers: Evaluation of reproductive parameters.

Post-operative pain and inflammation are normal physiological reactions to caesarean section. Their management in cattle have rarely been investigated. This surgical procedure negatively affects reproductive function with, for example, a reduction in fertility resulting in an increase in calving interval. In this multicenter clinical trial, the objective was to evaluate the impact on reproductive performance of meloxicam injected before caesarean section to manage post-operative pain and inflammation. Meloxicam is a non-steroidal anti-inflammatory drug. One hundred and twenty-seven Charolais heifers (n = 127) were recruited from 47 farms in six French veterinary practices in the Burgundy region. The heifers underwent a non-elective standardized caesarean section operation. Heifers were randomly assigned to one of two groups: meloxicam (n = 66), intravenous meloxicam injection before surgery, or control (n = 61). Reproductive performance and health information were recorded from the time of the caesarean section to the next calving or to culling. In our study, meloxicam administration before caesarean section had no effect on the incidence of retained placenta (18.2% of treated vs 25.0% of control cows, p = 0.35). The pregnancy rate was higher in treated than in control cows (83.1% vs 67.8%, p = 0.04 after multivariate analysis) and a survival analysis showed that the median calving interval was 35 days shorter in the meloxicam (t50% = 417 days) compared to the control group (t50% = 452 days, p = 0.05). A trend was also observed for culling rate to be lower in treated (4.7%) compared to control cows (13.3%, p = 0.09). In conclusion, this study suggests that there is a beneficial effect of meloxicam administration before caesarean section on reproductive performance in Charolais heifers.

Progesterone plays a critical role in canine oocyte maturation and fertilization.

Canine oocyte maturation and fertilization take place within the oviducts under increasing plasma levels of progesterone (P4). In order to investigate the role of P4 in these processes, 51 beagle bitches were treated with the P4 receptor antagonist aglepristone at the end of proestrus and 32 females were kept untreated. Fifteen treated and 13 control bitches were inseminated at Days +1 and +2 after ovulation (Day 0). Stages of oocyte maturation and embryo development were determined after ovariectomy at different time points after ovulation. Aglepristone did not prevent ovulation but delayed the resumption of oocyte meiosis and inhibited its progression: first metaphase I (MI) stage was observed at 173 h postovulation and 39% of oocytes reached MII as late as 335 h postovulation in treated females whereas first MI occurred at 76 h and 100% of oocytes were in MII at 109 h postovulation in controls. Aglepristone extended the stay of morphologically normal oocytes within the oviducts: first signs of oocyte degeneration were observed at 335 h in treated versus 100- to 110-h postovulation in control bitches. In inseminated females, aglepristone prevented sperm progression toward the oviducts and fertilization, although motile spermatozoa were observed in the uterine tip flush and within the cranial uterine glands. A proteomic analysis of the tubal fluid from treated and control noninseminated bitches at Day +4 found evidence of 79 differential proteins potentially involved in the oocyte phenotype. In conclusion, P4 plays key roles in postovulatory canine oocyte maturation, aging, and in fertilization.

OVGP1 is expressed in the canine oviduct at the time and place of oocyte maturation and fertilization.

In the dog, oocyte maturation, fertilization, and early embryo development take place within the oviduct in the presence of increasing circulating progesterone (P4) levels. Expression of the oviduct-specific glycoprotein 1 (OVGP1), known in other species to be estrogen-dependent, was explored by real-time quantitative reverse-transcriptase PCR, Western blotting, and immunohistochemistry in oviducts from adult Beagle bitches during anestrus and at five specific time periods around ovulation: during pro-estrus before the luteinizing hormone (LH) peak (Pre-LH); after the LH peak and before ovulation (Pre-ov); and at Days 1, 4, and 7 after ovulation (n = 6 bitches per stage). Plasma estradiol-17ß (E2) and P4 were assayed at all stages. The expression of canine OVGP1 (cOVGP1) was undetectable during anestrus, increased significantly from Pre-LH to Day 1 in parallel with a decrease in plasma E2-to-P4 levels, remained high at Day 4, then decreased at Day 7 in parallel with an increase in plasma P4 levels. In contrast to other mammals, the expression of cOVGP1 was higher in the isthmus than in the ampulla at all stages. In order to explore the potential regulation of cOVGP1 expression by steroids, the 5'-flanking region of the corresponding gene was analyzed for the presence of estrogen- (ERE) and P4-response-element (PRE). An imperfect ERE and three half-ERE were found in this region, but no PREs. In conclusion, cOVGP1 is highly expressed at the time and site of oocyte maturation and fertilization, and is probably under E2 regulation. Further studies are needed to identify the potential roles of cOVGP1 in each process.

PTGS2-related PGE2 affects oocyte MAPK phosphorylation and meiosis progression in cattle: late effects on early embryonic development.

During the periovulatory period, the induction of prostaglandin G/H synthase-2 (PTGS2) expression in cumulus cells and associated prostaglandin E2 (PGE2) production are implicated in the terminal differentiation of the cumulus-oocyte complex. During the present study, the effects of the PTGS2/PGE2 pathway on the developmental competence of bovine oocytes were investigated using an in vitro model of maturation, fertilization, and early embryonic development. The specific inhibition of PTGS2 activity with NS-398 during in vitro maturation (IVM) significantly restricted mitogen-activated protein kinase (MAPK) activation in oocytes at the germinal vesicle breakdown stage and reduced both cumulus expansion and the maturation rate after 22 h of culture. In addition, significantly higher rates of abnormal meiotic spindle organization were observed after 26 h of culture. Periconceptional PTGS2 inhibition did not affect fertilization but significantly reduced the speed of embryo development. Embryo output rates were significantly decreased on Day 6 postfertilization but not on Day 7. However, total blastomere number was significantly lower in embryos obtained after PTGS2 inhibition. The addition of PGE2 to IVM and in vitro fertilization cultures containing NS-398 overrode oocyte maturation and early embryonic developmental defects. Protein and mRNA expression for the prostaglandin E receptor PTGER2 were found in oocytes, whereas the PTGER2, PTGER3, and PTGER4 subtypes were expressed in cumulus cells. This study is the first to report the involvement of PGE2 in oocyte MAPK activation during the maturation process. Taken together, these results indicate that PGE2-mediated interactions between somatic and germ cells during the periconceptional period promote both in vitro oocyte maturation and preimplantation embryonic development in cattle.

Expression of enzymes involved in the synthesis of prostaglandin E2 in bovine in vitro-produced embryos.

Prostaglandin E2 (PGE2) may play a major role in embryo development and the establishment of pregnancy in cattle. The biosynthesis of PGE2 implies the sequential transformation of arachidonic acid to PGH2 by cyclooxygenases (COXs), then the conversion of PGH2 to PGE2 by prostaglandin E synthases (PGESs). Quantitative RT-PCR was used to examine the expression of COX-1, COX-2, microsomal PGES-1 (mPGES-1), microsomal PGES-2 (mPGES-2) and cytosolic PGES (cPGES) mRNAs in day 7 in vitro-produced (IVP) embryos from oocytes collected by ovum pick-up in Holstein heifers. Transcripts for COX-2 and mPGES-1 were detected in all embryos, whereas transcripts for COX-1 and mPGES-2 were not detected and cPGESs were at the limit of detection in 40% of embryos. Levels of COX-2 and mPGES-1 mRNAs were significantly higher in blastocysts and expanded blastocysts than in morulae and early blastocysts. Furthermore, excellent-quality embryos (grade 1) displayed higher levels of both COX-2 and mPGES-1 than did embryos of good and medium qualities (grades 2-3). Our results suggest that bovine IVP embryos at the morula and blastocyst stages use exclusively the COX-2/mPGES-1 pathway for PGE2 biosynthesis, and that PGE2 is potentially involved in blastocyst expansion and developmental competence.

Expression of genes involved in prostaglandin E2 and progesterone production in bovine cumulus-oocyte complexes during in vitro maturation and fertilization.

Prostaglandin E(2) (PGE(2)) and progesterone appear to be critical mediators of cumulus expansion and the resumption of oocyte meiosis. The aim of this study was to identify the types of prostaglandin E synthase (PTGES) expressed in the bovine cumulus-oocyte complex (COC), to characterize their temporal expression during the periconceptional interval using an in vitro model of maturation (IVM) and fertilization (IVF), and to compare their expression with the level of steroidogenic gene expression. Real-time RT-PCR analysis revealed that enzymes related to the PGE(2) biosynthesis pathway were mainly expressed during IVM. Transcripts encoding PTGES1-3 were detected in bovine COCs. Only the expression of PTGES1 significantly increased during IVM whereas that of PTGES2 and PTGES3 remained unchanged. The induction of PTGES1 expression paralleled the induction of prostaglandin G/H synthase-2 (PTGS2) expression and the amounts of PGE(2) secreted by maturing COCs. Concomitantly, cholesterol side chain cleavage cytochrome P450 expression was significantly upregulated in maturing COCs and the high level of expression persisted in fertilized COCs. The expression of the StAR protein remained constant during IVM and then decreased significantly during IVF. Expression of the progesterone catabolic-related enzyme, 20alpha-hydroxysteroid dehydrogenase significantly decreased throughout the periconceptional interval. This was associated with a rising level of progesterone released by COCs in the culture media. In conclusion, our results suggest that the periconceptional differentiation of the bovine COC includes the transient induction of PGE(2) biosynthetic activity via the PTGS2/PTGES1 pathway during the maturation period and the increasing ability to produce progesterone from the immature to the fertilized stages.

Effect of a supplement rich in linolenic acid added to the diet of post partum dairy cows on ovarian follicle growth, and milk and plasma fatty acid compositions.

The objective of this study was to determine the effect of a linseed supplement on follicle growth, progesterone concentrations and milk and plasma fatty acids in dairy cows post partum. Sixteen Holstein cows were given a basal total mixed diet plus one of two supplements: control (C; extruded soybeans; n = 8) or linseed (L; extruded linseeds; n = 8). One month after calving oestrous cycles were synchronised (PRID). Follicle growth and milk progesterone concentrations were measured every 2 d over the induced oestrous cycle. Milk production characteristics were unaffected by treatment. The L cows lost significantly more BCS than the C cows (P < 0.01). Plasma insulin, glucose and urea were unaffected by the treatment. Plasma NEFA tended to be affected by the treatment (L > C, P = 0.08). The proportions of 18:3n-3 in milk and plasma were increased by L compared to C (P < 0.001 and P < 0.01, respectively). There was an effect of dietary supplement on the numbers of small follicles (L < C, P < 0.05). Milk progesterone was unaffected by treatment. In conclusion, the increased supply of 18:3n-3 to the cows had only a modest effect on follicle populations and corpus luteum activity was unchanged.