The influence of indomethacin on the hatching of mouse blastocysts

Cyclooxygenase-2-derived endogenous prostacyclin enhances mouse embryo hatching

INTRODUCTION

The role of prostaglandins (PGs) in embryo hatching remains controversial. In addition, there is no direct evidence that mouse embryos synthesize PGs.

METHODS

The effects of endogenous PG on mouse embryo hatching were evaluated by blocking endogenous PG synthesis with indomethacin. Specific cyclooxygenase (COX) inhibitors were used to identify the role of COX-1- and COX-2-derived PGs. An eicosanoid profile was generated by incubating blastocysts with [3H]arachidonic acid and analysing the metabolites by high performance liquid chromatography. The expression and the localization of COX-1, COX-2 and prostacyclin synthase (PGIS) were examined by western blot analysis and immunohistochemistry.

RESULTS

The hatching of embryos cultured in 30 microl of protein-free medium was blocked by indomethacin (P = 0.007) or a selective COX-2 inhibitor (P = 0.004). Adding back iloprost, a prostacyclin analogue, abolished the effects of the COX-2 inhibitor. Prostacyclin was the most abundant PG produced by mouse blastocysts, which expressed COX-1, COX-2 and PGIS. COX-1, COX-2 and PGIS were expressed in 4-cell stage embryos and beyond; they were present in the inner cell mass and the trophectoderm of the blastocysts.

CONCLUSION

Mouse embryos express COX-1, COX-2 and PGIS which catalyse the formation of PGI2; COX-2-derived PGI2 plays a critical role in embryo hatching.

Effects of low chronic ethanol exposure on prostaglandin E synthesis by preimplantation mouse embryos

Embryo prostaglandin (PG) synthesis plays a role in the modulation of embryo metabolism and viability, and in the beginning of the implantation. The effects of ethanol consumption seem to be mediated at least in part by PGs. Increased PG production of postimplantation embryos is associated with retardation and abnormalities in the gestational period. The aim of this study was to find out the effects of low chronic ethanol ingestion by mice, previous to pregnancy, on the PGE released by in vitro and in vivo derived embryos. Immature females or adult males were treated with 5% ethanol for 30 days. After fertilization and mating, two-cell embryos, morulae and blastocysts were collected. The PGE synthesis and release were measured by radioimmunoassay. PGE production by in vitro derived two-cell embryos from ethanol-treated females was lower than in the control group (P < 0.01). Also, PGE production was reduced when two-cell embryos came from ethanol-treated males (P < 0.01). There were no differences in PGE synthesis by in vitro derived morulae and blastocysts in these groups. Two-cell embryos derived from mating produced lower quantities of PGE when they came from ethanol-treated females mated with control males, as compared to the control group. PGE release by in vivo derived blastocysts from ethanol-treated females was reduced significantly, as compared to the control group (P < 0.01). We conclude that a low concentration of ethanol administered chronically to immature females reduces PGE synthesis and release by two-cell embryos from culture in vitro, and by embryos of days 2 and 4 from in vivo development.

Ofloxacin: the next generation of antibiotic in sperm and embryo cultures for assisted reproductive technologies

OBJECTIVE

To analyze the effect of different concentrations of ofloxacin on sperm kinematic parameters and to determine the embryotoxicity of ofloxacin at physiologic and at 100x concentrations.

DESIGN

Prospective comparative study.

SETTING

Clinical and academic research environment.

PATIENT(S)

Pooled cryopreserved donor sperm (n = 7).

INTERVENTION(S)

Human sperm were processed through two-layer discontinuous Percoll gradients, and the resultant pellet was resuspended in either HEPES-buffered human tubal fluid medium containing different concentrations of ofloxacin or the control medium. After measuring the kinematic parameters, the percentages of apoptosis and viability were obtained. Next, the sperm DNA was extracted and polymerase chain reaction of beta-globin gene was performed followed by denaturing gradient gel electrophoresis. Mouse embryos recovered at the one-cell pronuclear or zygote stages were cultured in the presence or absence of ofloxacin up to the hatched blastocyst stage and differences in development were recorded.

MAIN OUTCOME MEASURE(S)

Sperm kinematic parameters, sperm beta-globin gene, and number of embryos reaching the hatched blastocyst stage.

RESULT(S)

The number of embryos exposed to control and physiologic ofloxacin concentrations showed comparable excellent growth. However, the 100x concentration significantly arrested development. Rates of sperm viability and apoptosis measured 48 hours after exposure to the above concentrations were not different from controls. No differences were noted in the sperm kinematic parameters of sperm exposed to ofloxacin concentrations (1x, 10x, and 100x) or control medium after 0, 4, and 48 hours of incubation. Denaturing gradient gel electrophoresis of beta-globin genes from DNA exposed to varying ofloxacin concentrations failed to show any point mutations.

CONCLUSION(S)

Ofloxacin was embryotoxic at pharmacologic concentrations (100x). At physiologic or higher concentrations, ofloxacin appears to be safe and does not affect sperm kinematic parameters when compared with controls. This may indicate that sperm motility parameters alone cannot be relied on to evaluate the effects of drugs on fertility and that in vitro embryologic studies are essential. Ofloxacin at any concentration did not alter the rates of sperm apoptosis or viability. Ofloxacin does not appear to be mutagenic as evidenced by the beta-globin gene analysis.

Influence of embryos on PGF2 alpha production by uterine tissue in pregnant mice

The aims of the present study are to find out if preimplantation mice embryos can synthesize prostaglandins and if the presence of the embryos in the uteri modifies the uterine prostaglandin synthesis. Both uteri of adult pregnant mice and embryos were collected at day two, three and four of pregnancy and the synthesis and release of PGE and PGF2 alpha was measured by radioimmunoassay. At day five of pregnancy, embryos are tightly adherent to epithelium, so tied uterine horns (without embryos) were compared to control uteri (with embryos). We found that embryos synthesize PGE and PGF2 alpha and that PGE is significantly greater on the fourth day of pregnancy than on the second and third day (P < 0.001). In the uteri, during the four days of pregnancy, there is a significant increase in PGE (P < 0.05) and a significant decrease in PGF2 alpha (P < 0.01). On the fifth day, the synthesis of PGF2 alpha was significantly greater in tied uteri than in controls (P < 0.05). We conclude that mice embryos can synthesize prostaglandins and their presence in uteri significantly decreased the synthesis of PGF2 alpha during the peri-implantation period without modifying the production of PGE.