Direct effects of oestradiol-17 beta and prostaglandin E-2 in protecting pig corpora lutea from a luteolytic dose of prostaglandin F-2 alpha

Implants containing vehicle or oestradiol-17 beta (10 mg) were placed into pairs of corpora lutea (CL) with and without prostaglandin F-2 alpha (PGF-2 alpha) (100 micrograms) on Day 11 and CL were collected on Day 19, in cyclic gilts (Exp. 1). The results demonstrated that CL implanted with PGF-2 alpha with or without oestradiol-17 beta had a markedly lower (P less than 0.01) weight (mg) and progesterone concentration (ng/mg) than CL with vehicle-or oestradiol-17 beta-implanted or unimplanted CL, which were similar (149 and 7.2 vs. 304 and 49.6, respectively). In Exp. 2, CL implanted with vehicle, oestradiol-17 beta or PGE-2 remained fully functional until Day 19, whereas CL implanted with oestradiol-17 beta +/- PGF-2 alpha and PGE-2 + PGF-2 alpha exhibited lower (P less than 0.05) weight and progesterone concentrations; CL implanted with PGE-2 + PGF-2 alpha were heavier (P less than 0.05) and tended (P less than 0.10) to have greater progesterone concentrations than CL implanted with oestradiol-17 beta + PGF-2 alpha. In Exp. 3, a dose-dependent (P less than 0.05) effect of PGE-2 on preventing regression induced by PGF-2 alpha was observed on Day 19. These data demonstrate a direct effect of PGE-2, but not of oestradiol-17 beta in protecting the CL against luteolysis induced by PGF-2 alpha.     

Influence of hCG injection and steroid treatment on prostaglandin metabolism by rabbit uterus and oviduct

Metabolism of PGE-2 and PGF-2 alpha by cytosolic fractions (100 000 g supernatant) of rabbit uterus, oviduct and lung was measured in vitro. Metabolism of PGE-2 was greater than that of PGF-2 alpha for oviduct and uterus. After an ovulating injection of hCG metabolism of both PGE-2 and PGF-2 alpha by lung and uterus declined linearly up to 72 h (during the time of ovum transport). The amount of PG metabolism by the oviduct did not change significantly during this period, but the percentage changes of PGE-2 and PGF-2 alpha metabolism from oestrous values did differ, and perhaps indicated a change in the ratio of intracellular PGs. No change of metabolism of either PG by lung, uterus or oviduct occurred at 24 or 72 h after an injection of 250 micrograms oestradiol cyclopentylpropionate given concomitantly with the hCG (a treatment regimen which causes 'tube-locking' of ova). However, progesterone treatment, in a regimen known to cause accelerated transport of ova through the oviduct, caused significantly enhanced metabolism of both PGE-2 and PGF-2 alpha by uterus and oviduct, but not lung, 30 and 48 h later except for PGE-2 by uterus at 30 h. These results suggest that changes in metabolism of PGE-2 and PGF-2 alpha by the oviduct may be involved in the mechanisms controlling ovum transport.     

Effects of prostaglandins on ovarian blood flow in the bitch

Oestrus and anoestrous mongrel dogs were anaesthetized with chloralose-urethane. In one group, the ovaries were isolated in situ and the effects of a 15-min infusion of PGF-2alpha or PGE-2 on perfusion pressure were measured. In the other group, heated thermocouples were introduced into the stroma of each ovary to measure the changes of local blood flow in response to PGF-2 alpha and PGE-2 infused into the ovarian bursa for 15 min. Intra-arterial infusion of 25.50, 100 or 200 ng PGF-2alpha/kg/min did not affect perfusion pressure; PGE-2 doses of 3.1, 6.2, 12.5 or 25 ng/kg/min caused reductions in proportion to the dose. All doses of PGE-2alpha (50.0, 100 or 200 ng/kg/min) or PGE-2 (25, 50 or 100 ng/kg/min) increased blood flow in the ovarian stroma in proportion to the dose when administered by infusion into the ovarian bursa. There were no differences in the results from oestrous and anoestrous dogs. It is concluded that PGF-2alpha changes intraovarian blood distribution without interfering with the total blood flow while PGE-2 increases both the total and local ovarian blood flow.     

A possible explanation for the refractoriness of uterine prostaglandin production

Arachidonic acid increased the outputs of prostaglandin (PG) F-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus superfused in vitro. Similar increases in PG output were observed when the arachidonic acid treatment was repeated after an interval of 1, 3 or 5 h. Phospholipase (PL) A-2 increased the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus, but repeating the PLA-2 treatment 1 h later failed to stimulate PG output. The increase in outputs of PGF-2 alpha and PGE-2 caused by PLA-2 were partly restored after 3 h and were fully restored after 5 h, whereas the increase in 6-keto-PGF-1 alpha output produced by PLA-2 was only partly restored after 3 and 5 h. PLA-2 had little or no effect on PGF-2 alpha and PGE-2 outputs from the Day-15 guinea-pig uterus initially, and when repeated after 1, 3 and 5 h. This was probably due to the output of these two PGs, particularly of PGF-2 alpha, being stimulated in vivo before removal of the uterus. PLA-2 increased 6-keto-PGF-1 alpha output from the Day-15 uterus initially, but failed to cause a response when administered again 1 h later. After 3 and 5 h, the increase in 6-keto-PGF-1 alpha output from the Day-15 uterus caused by PLA-2 was partly restored. A23187 and PLC increased the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus. These responses to A23187 and PLC were reduced (but not abolished) when the two compounds were administered again 1 h later. After 3 and 5 h, the increases in output of PGF-2 alpha and PGE-2 produced by A23187 and PLC had returned to the initial values. The increases in output of 6-keto-PGF-1 alpha from the Day-7 and Day-15 guinea-pig uterus produced by A23187 and PLC were partly restored after 3 and 5 h, except for the response to PLC on Day 7 which was fully restored after 5 h. The results show that there is no failure with time in the mechanism which converts arachidonic acid into PGF-2 alpha in the guinea-pig uterus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Prostaglandin production by the early pregnant guinea-pig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

The outputs of prostaglandin (PG) F-2 alpha and PGE-2, but not of 6-oxo-PGF-1 alpha, from the guinea-pig uterus were significantly lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle. Uterine PGF-2 alpha output increased 28-fold between Days 7 and 15 of the cycle but only 4- to 5-fold between these same days of pregnancy. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs increased 2- to 3-fold between Days 7 and 15 of the cycle and of pregnancy. Endometrial PGF-2 alpha synthesizing capacity was 60-70% lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle, although it increased 2-fold and 2.5-fold between these days of pregnancy and of the cycle, respectively. Endometrial PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities showed no significant variation amongst Days 7 and 15 of the cycle and of pregnancy, except that endometrial PGE-2 synthesizing capacity was lower on Day 7 of the cycle. Oestradiol treatment (10 micrograms s.c. daily from Days 10 to 14 of pregnancy) did not affect plasma progesterone concentrations, uterine 6-oxo-PGF-1 alpha output, and endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities in 9/12 guinea-pigs when examined on Day 15. Uterine PGF-2 alpha and PGE-2 outputs increased 3- and 1.5-fold, respectively, in these guinea-pigs, but were still much lower than the outputs from the Day-15 non-pregnant uterus. The pregnancies appeared unaffected in these oestradiol-treated guinea-pigs. In the other 3 oestradiol-treated animals, uterine PGF-2 alpha output was 20- to 30-fold higher than in untreated, pregnant guinea-pigs on Day 15, and 2- to 3-fold higher than in Day-15 non-pregnant guinea-pigs. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs also tended to be higher in these treated guinea-pigs. In these 3 guinea-pigs, endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities were 4.0-, 3.4- and 2.5-fold higher, respectively, than in untreated, pregnant guinea-pigs on Day 15, and tended to be higher than in Day-15 non-pregnant guinea-pigs. Plasma progesterone concentrations were much lower in these 3 animals than in the other 9 treated with oestradiol, and also much lower than in untreated, pregnant guinea-pigs on Day 15.(ABSTRACT TRUNCATED AT 400 WORDS)     

Studies on prostaglandin metabolism in corpora lutea of rabbits during pregnancy and pseudopregnancy

Corpora lutea and ovarian stromal tissue were analysed for prostaglandin (PG) concentrations and activities of enzymes involved in PG metabolism at 8, 10, 12, 13 and 15 days after induction of ovulation. In CL of pseudopregnant rabbits, the PGE-2-9-ketoreductase (PGE-2-9-KR) was highly active on Days 10, 12 and 15 when compared with Day 8 (P less than 0.01; P less than 0.001; P less than 0.05). In pregnant animals PGE-2-9-KR activity was only increased on Day 12 (P less than 0.05) but declined to basal levels on Days 13 and 15. Comparing PGE-2-9-KR activity of pseudopregnant and pregnant animals, a significant elevation was found on Day 15 of pseudopregnancy (P less than 0.025). Activities of PG-15-hydroxydehydrogenase did not exhibit any significant changes with time in pseudopregnant or pregnant rabbits. PGE-2 concentrations were increased on Days 12, 13 and 15 (P less than 0.025) when compared with Day 8. Changes in PGF-2 alpha concentrations paralleled those of PGE-2-9-KR. The concentrations of PG metabolites 13,14-dihydro-15-keto-PGE-2 and -PGF-2 alpha were lower than those of the primary PGs and did not show stage-specific changes in pseudopregnant and pregnant animals. These results demonstrate that the rabbit CL possesses enzymes to convert PGE-2 to PGF-2 alpha and to metabolize both PGs. PGE-2-9-KR may be involved in regulating the PGF-2 alpha/PGE-2 ratio and possibly in controlling the life-span of the corpus luteum.     

Uterine contractile activity in rats induced by mifepristone (RU 486) in relation to changes in concentrations of prostaglandins E-2 and F-2 alpha.

Pregnant rats were injected with mifepristone (RU 486) on Day 15 of pregnancy. The force and frequency of uterine contractions, recorded by a microballoon technique, were significantly greater at 12, 24 and 36 h in treated than in control rats (11.9 +/- 1.9 vs. 8.9 +/- 1.2 units, 17.7 +/- 3.0 vs. 10.5 +/- 2.3 units and 16.8 +/- 2.9 vs. 8.8 +/- 1.8 units for force and 51.3 +/- 9.1 vs. 29.4 +/- 3.8/h, 35.4 +/- 6.4 vs. 22.1 +/- 4.9/h and 35.6 +/- 3.2 vs. 24.6 +/- 4.6/h for frequency, respectively). There was no significant difference in concentrations of prostaglandin (PG) E-2 or PGF-2 alpha between treated and control rats at 12 h and 24 h after injection. At 36 h, 7 of 12 rats were aborting and uterine PG concentrations in these were significantly greater than in the others (1.5 +/- 0.2 vs. 0.9 +/- 0.2 ng PGE-2/g and 38.6 +/- 19.2 vs. 16.9 +/- 5.4 ng PGF-2 alpha/g), but there was no significant difference between control and treated rats that were not aborting. Concentrations of PGE-2 and PGF-2 alpha were significantly higher at 48 h when abortion had occurred in all animals (6.5 +/- 2.6 vs. 2.4 +/- 1.7 ng PGE-2/g and 30.4 +/- 8.9 vs. 9.3 +/- 5.6 ng PGF-2 alpha/g). Thus, the increase in uterine contractile activity induced by mifepristone preceded significant changes in concentrations of PGE-2 and PGF-2 alpha in the uterus and so could not have been caused by these changes.     

Further studies on prostaglandin and thromboxane production by the rat uterus during the oestrous cycle

Prostaglandin (PG) and thromboxane (TX) synthesis by uterine homogenates was measured at 4-h intervals during the 4-day oestrous cycle of rats. Production was in the order of 6-oxo-PGF-1 alpha (which reflects PGI-2 synthesis) greater than PGF-2 alpha greater than TXB-2 (which reflects TXA-2 synthesis) greater than or equal to PGE-2. Peak production occurred at 02:00 h on the day of oestrus, after which production gradually decreased, with some fluctuation on the day of metoestrus, to reach a minimum between 22:00 and 06:00 h on the days of dioestrus and oestrus, respectively. Separation of the uterine tissues showed that, on a unit weight basis, the endometrium had a much higher PG and TX synthesizing ability than did the myometrium, although this was compensated for on a total weight basis by the much greater mass of myometrium. Endometrial PG and TX production was in the order of PGF-2 alpha greater than TXB-2 greater than or equal to 6-oxo-PGD-1 alpha identical to PGE-2, with PGF-2 alpha and TXB-2 productions showing the greatest increases between 10:00 and 02:00 h on the days of pro-oestrus and oestrus, respectively. Myometrial PG and TX production was in the order of 6-oxo-PGF-1 alpha greater than PGF-2 alpha greater than PGE-2 identical to TXB-2, with 6-oxo-PGF-1 alpha and PGF-2 alpha productions showing small increases between 10:00 and 02:00 h on the days of pro-oestrus and oestrus, respectively. Myometrial PGE-2 production decreased between these two times.(ABSTRACT TRUNCATED AT 250 WORDS)     

Investigations into the mechanism by which sodium fluoride stimulates prostaglandin production in guinea-pig uterus

Sodium fluoride (10 mM) caused a slow increase in the outputs of PGF-2 alpha, 6-keto-PGF-1 alpha and, to a lesser extent, PGE-2 from the Day-7 and Day-15 guinea-pig uterus superfused in vitro. This stimulatory action of sodium fluoride was not prevented by using calcium-free Krebs' solution. There was also a faster stimulation of 6-keto-PGF-1 alpha output from the Day-7 guinea-pig uterus produced by sodium fluoride, and this quicker response was abolished by using calcium-free Krebs' solution. TMB-8 (an intracellular calcium antagonist) inhibited the stimulatory action of sodium fluoride on the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus. W-7 and trifluoperazine (calmodulin antagonists) and neomycin (an inhibitor of phospholipase C) had no inhibitory effect on the increases in outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus produced by sodium fluoride. These results indicate that sodium fluoride slowly stimulates uterine PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha synthesis in the guinea-pig uterus by mobilizing intracellular calcium by a mechanism which apparently does not involve the activation of phospholipase C or the participation of calmodulin (or a related compound). The initial, faster stimulation of 6-keto-PGF-1 alpha synthesis in the Day-7 guinea-pig uterus by sodium fluoride is dependent upon extracellular calcium.     

Prostaglandin specific binding in hamster myometrial low speed supernatant.

A charcoal adsorption method was developed to measure specific prostaglandin binding in low speed supernates of hamster myometrial homogenates. This method was used to characterize and quantitate PGE-1-specific binding. The equilibrium binding constants and the concentration of specific PGE-1 binding sites were determined during the hamster estrous cycle. The apparent association constant for 12 different preparations was 1.16 plus or minus 0.08 times 10-9M-1. The concentration of PGE-1 specific binding sites was significantly higher on days 2 and 3 of the estrous cycle that it was on days 1 or 4. The competition for PGE-1 binding sites by PGE-2, PGF-2alpha, tpga-1 and various PGE-1 metabolites and derivatives was measured in hamster myometrial homogenates. Relative affinities of the natural prostaglandins for the PGE-1 binding sites, calculated by parallel line assay, were: PGE-2 greater than PGE-1 greater than PGA-1 greater than PGF-2alpha. For PGE-1 metabolites the relative affinities were: PGE-1 greater than 13,14-dihydro-PGE-1 greater than 13,14-dihydro-15-keto-PGE-1 greater than 15-keto-PGE-1. For the analogs and derivatives the compounds tested ranked as: 16,16-dimethyl-PGE-1 greater than PGE-1 methyl ester greater than 17-phenyl-18,19,20-trinor-PGE-1 greater than 15(S) 15-methyl-PGE-1 methyl ester. Arachidonic acid, bis-homo-gamma-linolenic acid and 7-oxa-13 prostynoic acid had relative affinities greater than 0.1 compared to PGE-1 equal 100. Indomethacin had a relative affinity of 0.4 compared to PGE-1.     

In-vitro prostanoid production by the rat vas deferens

Prostaglandins (PGs), E-2, F-2 alpha, 6-keto-F-1 alpha and thromboxane B-2 (TXB-2), produced in vitro by the vas deferens of rats at different stages of sexual maturation (10, 35 and 100 days of age), were estimated by radioimmunoassay. Reversed-phase high-performance liquid chromatography was used to evaluate the RIA and to give a more complete profile, after incubation of the vas deferens with [14C]arachidonic acid. The amount of PGE-2 released into the medium after incubation at 37 degrees C for 5 min increased with age, and was the predominant prostanoid in the adult vas deferens. In prepubertal organs, 6-keto-PGF-1 alpha predominated. TXB-2 was always a minor product. The addition of exogenous arachidonic acid (10 micrograms/ml/20 mg tissue), provoked a higher production of the four compounds. PGE-2 and PGF-2 alpha levels were reduced after castration or hypophysectomy and were re-instated after treatment with testosterone propionate. PGE-2 was much more sensitive to hormonal deprivation than PGF-2 alpha. The production of 6-keto-PGF-1 alpha was not significantly affected by the above treatments.     

Effect of melittin on prostaglandin production by guinea-pig uterus.

Melittin, an activator of phospholipase (PL) A-2, increased the outputs of prostaglandin (PG) F-2 alpha and 6-keto-PGF-1 alpha, but not of PGE-2, from Day-7 guinea-pig uterus superfused in vitro. Reducing the extracellular calcium concentration (by omitting calcium chloride from the superfusing fluid) partially inhibited the stimulatory effect of melittin on uterine PG production. TMB-8 (an intracellular calcium antagonist) completely prevented the stimulation of PGF-2 alpha and 6-keto-PGF-1 alpha output by melittin, although the production of both PGs tended to increase after stopping the melittin and TMB-8 treatments. TMB-8 also inhibited the increases in outputs of PGF-2 alpha, 6-keto-PGF-1 alpha and PGE-2 and prevented contraction of the uterus induced by exogenous PLA-2. Trifluoperazine (a calmodulin antagonist) had no inhibitory effect on the increases in outputs of PGF-2 alpha and 6-keto-PGF-1 alpha produced by melittin; it potentiated the stimulatory effect of melittin on 6-keto-PGF-1 alpha output and allowed melittin to increase PGE-2 output. When melittin was applied twice to the superfused uterus with an interval of 1 h between each treatment, partial refractoriness of the responses to melittin was seen: the magnitudes of the increases in PGF-2 alpha and 6-keto-PGF-1 alpha outputs were 40-50% less after the second treatment than after the first treatment. These results show that melittin stimulates the synthesis of PGF-2 alpha and PGI-2 (measured as 6-keto-PGF-1 alpha) in guinea-pig uterus by mechanisms which are calcium dependent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of prostaglandins E-2 and F-2 alpha on the metabolism of [U-14C]glucose by mouse morulae-early blastocysts in vitro

During 5-h culture in the presence of radioactive glucose, PGE-2 (10 micrograms/ml) significantly inhibited incorporation of glucose into the acid-soluble glycogen pool. PGE-2 at 1 and 10 micrograms/ml and PGF-2 alpha at 1 microgram but not 10 micrograms/ml stimulated incorporation of glucose into non-glycogen macromolecules during culture. However, the utilization of acid-soluble glycogen and other biochemical pools was not affected by the presence of PGs in the medium during 24-h chase culture of pulse-labelled embryos. Carbon dioxide production was significantly suppressed in the presence of PGs but accumulation of lactate was not affected. The results indicate that PGE-2 and PGF-2 alpha, in physiological concentrations, directly influence the metabolism of glucose by preimplantation embryos.     

Effects on fertilization of rabbits of insemination with ejaculates treated with PG-dehydrogenase and antisera to PGE-2 and PGF-2 alpha

PGE-2 and PGF-2 alpha in rabbit semen were selectively inactivated by incubation with antisera, or most of the seminal prostaglandins were transformed into biologically inactive 15-keto-prostaglandins by prostaglandin-15-hydroxydehydrogenase(PG-15-HDH). These treated ejaculates were vaginally inseminated. Compared to the controls (738 eggs of which 94% were fertilized) a dose-dependent reduction of the fertilization rate was observed with the anti-PGF-2 alpha-treated ejaculates. A non-uniformly, but statistically significantly reduced fertility was found in the other 2 treatment groups. After incubation with higher doses of PG-15-HDH, some fertilization was accomplished with ejaculates showing an extremely weak forward progression or immotile spermatozoa. An improvement in sperm motility, however, was observed in ejaculates treated with antiserum to PGF-2 alpha. Seminal prostaglandins may not exclusively affect sperm motility. The observed influences on the fertilization rate after treatment of spermatozoa with antisera to PGE-2 and PGF-2 alpha or PG-15-HDH suggest that these are local effects in the female genital tract.     

Significance of intracellular calcium and cyclic adenosine 3',5'-monophosphate in the mechanisms by which prostaglandins influence human sperm function

The selective ability of PGE-1 and PGE-2 to enhance the capacity of human spermatozoa for hamster oocyte penetration was dependent upon high concentrations (1.7 mM) of extracellular Ca2+ and a prolonged (4 h) duration of exposure, and insensitive to the Ca2+ channel antagonist, verapamil. Studies with the intracellular calcium indicator Quin-2 indicated that exposure to PGE-1 and PGE-2, but not PGF-2 alpha, induced a significant rise in the levels of cytoplasmic Ca2+, suggesting that an ionophore-like action might be responsible for the ability of the E-series prostaglandins to influence sperm function. Stimulation of oocyte penetration with PGE-1 and PGE-2 was significantly enhanced when these compounds were presented to the spermatozoa in medium of high osmolarity (410 mosmol). A combination of PGE-1 in hyperosmotic medium did not significantly influence sperm function in cases of oligozoospermia, although it was effective with patients exhibiting idiopathic infertility. Exposure to high doses of PGE-1 and PGE-2, but not 19-hydroxy PGE or PGF-2 alpha, also induced a significant rise in the cyclic AMP content of human spermatozoa. This effect did not appear to be involved in the enhancement of fertilization rates because it did not exhibit the same absolute dependence on high levels of extracellular Ca2+ as did the fertilization responses and the enhancement of oocyte penetration and the elevation of cAMP were independent of each other within the patient population.     

Prostaglandins in maternal and fetal plasma and in allantoic fluid during the second half of gestation in the mare.

The concentrations of the primary prostaglandins (PG) F-2alpha and E-2 and the metabolite 13,14-dihydro-15-oxo-prostaglandin (PGFM) in maternal and fetal plasma and in allantoic fluid were measured in chronically catheterized mares and fetuses. A gradual rise in all 3 PGs occurred with increasing gestational age. PGE-2 and PGF-2 alpha levels were highest in the allantoic fluid and lowest in the maternal plasma, whereas PGFM concentrations were greatest in maternal plasma. Significant venous-arterial plasma differences in PGFM concentration were detected across the uterine circulation between 180 and 280 days gestation. The 3--5-fold rise in maternal PGFM associated with fasting or intrauterine surgery was virtually abolished by meclofenamic acid, a prostaglandin synthetase inhibitor. Increases in PGE-2 and PGF-2 alpha in the fetal fluids preceded premature delivery of the foal, while PG changes in maternal plasma were minimal even 10--20 h before delivery.     

Is protein synthesis necessary for prostaglandin production by guinea-pig endometrium?

The outputs of prostaglandin (PG) F-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from Day-7 and Day-15 guinea-pig endometrium in culture were reduced by the inclusion of actinomycin D, cycloheximide and puromycin in the culture medium, with the output of PGF-2 alpha from Day-15 endometrium being particularly affected during the first 6 h of culture. The intrauterine administration of actinomycin D on Day 10 decreased the outputs of PGF-2 alpha and PGE-2, but not of 6-keto-PGF-1 alpha, from Day-15 endometrium in culture without affecting PG output from Day-15 myometrium in culture. Actinomycin D, cycloheximide and puromycin did not reduce PG output when superfused over the Day-7 and Day-15 guinea-pig uterus in vitro for 20 min, indicating that these compounds do not have a rapid inhibitory effect on endometrial PG synthesis. In fact, they tended to stimulate PG output during this 20-min period, with cycloheximide having a pronounced effect on PGE-2 output. The synthesis of secreted proteins, but not of cellular proteins, was greater by Day-15 than by Day-7 endometrium in culture. Actinomycin D, cycloheximide and puromycin inhibited the synthesis of secreted and cellular proteins by Day-7 and Day-15 endometrium in culture. Protein synthesis and PG synthesis in the endometrium were both inhibited to a greater extent by cycloheximide and puromycin than by actinomycin D. The intrauterine administration of actinomycin D on Day 10 reduced the syntheses of secreted and cellular proteins by Day-15 endometrium in culture. These findings indicate that the endometrial synthesis of PGs, particularly of PGF-2 alpha towards the end of the oestrous cycle, is dependent upon endometrial protein synthesis.     

Prostaglandin output from the early pregnant rat uterus superfused in vitro, and the effect of A23187 and trifluoperazine

The outputs of prostaglandin (PG) E-2 and 6-oxo-PGF-1 alpha from the early pregnant rat uterus superfused in vitro were significantly higher (P less than 0.05) on Day 4 (09:00-10:00 h) and Day 5 (14:00-15:00 h) than on Day 2 (09:00-10:00 h) and Day 5 (14:00-15:00 h). PGF-2 alpha output was significantly higher (P less than 0.05) only on Day 5 (09:00-10:00 h). PGE-2 was the major PG released at all times, although the amounts of PGF-2 alpha and/or 6-oxo-PGF-1 alpha released were often only slightly less. These findings are consistent with uterine PGs having a role in implantation in the rat. A23187 stimulated 6-oxo-PGF-1 alpha output and, except on Day 4 (09:00-10:00 h), PGF-2 alpha output at all times studied. A23187 had little effect on PGE-2 output. The greatest stimulatory effect of A23187 on 6-oxo-PGF-1 alpha and PGF-2 alpha outputs occurred on Day 5 (09:00-10:00 h), which is the day of highest uterine PGH-2 synthetase activity. These increases in response to A23187 were prevented by trifluoperazine (100 microM), a calmodulin antagonist. Trifluoperazine had no inhibitory effect on the high basal output of PGs on Day 5 (09:00-10:00 h), but caused a small increase in uterine PG output.     

Induction of avidin in the chick oviduct by tissue damage and prostaglandins

In immature, diethylstilboestrol-treated chicks, ligation of the oviduct caused local avidin synthesis in the immediate vicinity of the ligature. PGF-2alpha injected directly into the oviduct also induced avidin synthesis, whereas saline or PGE-2 had no effect. PGE and PGF-2alpha concentrations increased in the oviduct within 24 h of ligation: the PGE increase could be partly inhibited by indomethacin, whereas that of PGF-2alpha was less inhibited. An LD50 dose of indomethacin alone and with ligation had a clear stimulatory effect on avidin synthesis, whereas aspirin alone, or with ligation, was not effective. Ligation alone and with indomethacin appeared to alter the PGF-2alpha/PGE ratio. These results suggest that PGF-2alpha may be involved in the regulation of avidin synthesis in the chick oviduct.     

Detrimental effects of prostaglandin F2alpha 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.