The urinary excretion of prostaglandins and thromboxane B2 in healthy volunteers: a study in males and females, and on the influence of seminal fluid contamination

Radioimmunoassay measurements of prostaglandins (PGs) E2, F2 alpha, 6-keto-PGF1 alpha and thromboxane (Tx) B2 in 24 h urine specimens from a male and a female healthy volunteer on several consecutive days revealed a dramatic increase of PGE2, PGF2 alpha, 6-keto-PGF1 alpha on days, upon which they had sexual intercourse; only TxB2 remained stable. Furthermore, the PGE2/PGF2 alpha ratio rose to values greater than 0.5 on days with sexual intercourse. This was found to be due to contamination of the urine samples by seminal fluid. Two 24 h urine samples from each of 26 healthy male and female volunteers (HV) revealed higher (p less than 0.01) mean PGE2 and PGF2 alpha values in males than in females. The results show that the interpretation of the urinary PG excretion as a measure of renal PG synthesis should be considered carefully, and that a PGE2/PGF2 alpha ratio greater than 0.5 indicates probable seminal contamination of urine.     

Urinary excretion of prostaglandins during infancy and childhood: influence of age, sodium restriction and posture

The influences of age, sodium restriction and posture on 24-hour urinary excretion of prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF 2 alpha), 6-keto-prostaglandin F1 alpha (6-keto-PGF 1 alpha) and thromboxane B2 (TXB2) were investigated in 111 healthy children and youngsters in the age between 1 day and 16 years. A considerable degree of variation was found in normal 24-hour urinary prostaglandin excretion in all age groups. There was no significant effect of age on the urinary excretion of prostaglandins when data were corrected for body surface area. In addition, sodium restriction and posture had no influence on the excretion of PGE2, PGF 2 alpha, 6-keto-PGF 1 alpha and TXB2. Our results indicate that in the first days of life the kidney already has the capacity to synthesize prostaglandins in amounts comparable to older children.     

Production of prostaglandins by dispersed cells and fragments from bovine parathyroid glands

We studied the production of prostaglandins by fragments and dispersed cells from bovine parathyroid glands. Fragments released 138 +/- 19 (SE), 132 +/- 21, 4.3 +/- 0.5, and 13 +/- 6.6 pg/mg/h of 6-keto-PGF1 alpha, PGF2 alpha, PGE2, and thromboxane B2, respectively (n = 7 - 26), while dispersed cells released 414 +/- 110, 22 +/- 7.3, 27 +/- 3.8, and 29 +/- 11 pg/10(6) cells/h, respectively, of the same compounds (n = 6 - 25). Indomethacin (1 microgram/ml) inhibited the release of 6-keto-PGF1 alpha by 80-90% in fragments and cells, while mellitin stimulated release of this prostaglandin, suggesting de novo synthesis of prostaglandins in these preparations. Calcium stimulated production of 6-keto-PGF1 alpha by 1.3-fold in cells and 2.6-fold in fragments and also enhanced production of PGF2 alpha by 1.9-fold in fragments. Isoproterenol, on the other hand, had no effect on production of 6-keto-PGF1 alpha in either preparation. These results demonstrate that parathyroid tissue as well as parathyroid cells per se produce a variety of prostaglandins. We have previously shown that PGE2 and PGF2 alpha modulate cAMP accumulation and PTH release in dispersed bovine parathyroid cells. The role of the endogenous production of prostaglandins by the parathyroid gland in the acute or chronic regulation of parathyroid function, however, remains to be determined.     

Investigations into the mechanisms controlling prostaglandin production by the guinea-pig placenta: roles of calcium and gonadotrophin-releasing hormone

The outputs of PGF(2 alpha), PGE(2) and 6-keto-PGF(1 alpha) were higher from the day 29 guinea-pig placenta than from the sub-placenta in culture, with PGF(2 alpha)being the major prostaglandin produced by the placenta. Lack of extracellular calcium reduced the production of all three prostaglandins by the sub-placenta and 6-keto-PGF(1 alpha) production by the placenta, but had no effect on the production of PGF(2 alpha) and PGE(2) by the placenta. EGTA (a calcium chelator) and a low concentration (30 microM) of TMB-8 (an intracellular calcium antagonist) generally inhibited prostaglandin output from the placenta and sub-placenta at various time points during culture, although EGTA had no effect on PGE(2) output from the placenta. Trifluoperazine and W-7 (calmodulin inhibitors) had no inhibitory effect on the outputs of PGF(2 alpha) and PGE(2) from the placenta, nor on the outputs of any prostaglandin from the sub-placenta. However, these two compounds inhibited the output of 6-keto-PGF(1 alpha) from the placenta. Nifedipine and verapamil (calcium channel blocking drugs) generally reduced the outputs of prostaglandins from the placenta and sub-placenta, except verapamil had no inhibitory effect on PGF(2 alpha) output from the sub-placenta. Gonadotrophin-releasing hormone (GnRH) did not stimulate the output of prostaglandins from the placenta, and tended to have a weak inhibitory action on this tissue. On the sub-placenta, GnRH had an initial inhibitory action on the outputs of PGF(2alpha) and 6-keto-PGF(1 alpha), which was then followed by a stimulation of the outputs of PGF(2 alpha) and, to a lesser extent, of PGE(2).     

Comparison of plasma prostanoid levels in the human cord artery in normal and fetal distressed deliveries

Prostaglandin E2 (PGE2), thromboxane B2 (TXB2; as a stable metabolite of TXA2), prostaglandin F2 alpha (PGF2 alpha) and 6-keto-PGF1 alpha (as a stable end product of prostacyclin) have been measured by using specific radioimmunoassay in the plasma of the cord artery immediately after delivery before the cord was clamped. Plasma prostanoid concentrations in normal deliveries (n = 8, as controls) were 24.8 +/- 2.6 (PGE2), 246.8 +/- 37.0 (TXB2), 122.2 +/- 13.3 (PGF2 alpha) and 82.1 +/- 7.7 (6-keto-PGF1 alpha) respectively (pg/ml, mean +/- s.e). On the other hand, in fetal distressed deliveries showing continuous bradycardia (n = 6), they increased significantly to 275.4 +/- 20.1 (PGE2), 948.6 +/- 102.5 (TXB2), 218.0 +/- 21.4 (PGF2 alpha) and 1498.6 +/- 298.4 (6-keto-PGF1 alpha) respectively (pg/ml, mean +/- s.e, p less than 0.005). However, both PGF2 alpha/PGE2 and TXB2/6-keto-PGF1 alpha ratios declined significantly from 4.70 +/- 0.33 to 0.68 +/- 0.05 and from 3.07 +/- 0.37 to 0.68 +/- 0.12 respectively (mean +/- s.e, p less than 0.005) in the fetal distressed group compared with those of the controls. From these results, it may be concluded that the cord artery, which is known as the patent source for the production of PGE2 and prostacyclin, did exert a sufficiently strong reaction to overcome the undesirable haemodynamic changes to maintain the fetal well-being in utero.     

Interleukin-1 beta is a potent stimulator of prostaglandin synthesis in bovine luteal cells.

Interleukin-1 (IL-1) is a polypeptide that has both local and systemic effects on numerous tissues, including endocrine cells. To evaluate the effect of IL-1 on luteal function, bovine luteal cells were cultured for 5 days with increasing concentrations (0.1, 0.5, 1.0, 2.5, 5.0, 10.0 ng/ml) of recombinant bovine interleukin-1 beta (rbIL-1 beta). IL-1 beta increased the production of luteal 6-keto-prostaglandin-F1 alpha (6-keto-PGF1 alpha), prostaglandin E2 (PGE2), and prostaglandin F2 alpha (PGF2 alpha) in a dose-dependent manner, but had no effect on progesterone (P4) production. Treatment with the cyclooxygenase inhibitor, indomethacin (5 micrograms/ml), inhibited basal, as well as rbIL-1 beta-stimulated prostaglandin production. Addition of Iloprost (a synthetic analogue of prostacyclin, 5 ng/ml) suppressed basal production of PGF2 alpha and PGE2, but did not reduce the stimulatory effect of rbIL-1 beta. Similarly, PGF2 alpha suppressed basal, but not IL-1 beta-stimulated, production of 6-keto-PGF1 alpha. PGE2 had no effect on the synthesis of either PGF2 alpha or 6-keto-PGF1 alpha. P4 (1.75 micrograms/ml) reduced basal as well as rbIL-1 beta-stimulated production of 6-keto-PGF1 alpha, PGE2, and PGF2 alpha. These results indicate that IL-1 beta could serve as an endogenous regulator of luteal prostaglandin production. It appears that IL-1 beta action is not modified by exogenous prostaglandins, but is at least partially regulated by elevated P4. It is possible that the role of IL-1 beta in stimulation of luteal prostaglandin production may be confined to a period characterized by low P4 levels, such as during luteal development or regression.     

Prostaglandin production by cultured cynomolgus monkey trabecular meshwork cells

Monkey trabecular meshwork (MTM) cells synthesize a variety of prostaglandins, including large amounts of prostaglandin E2 (PGE2) and smaller amounts of 6-keto-PGF1 alpha and PGF2 alpha. The predominance of PGE2 production by the MTM cells is similar to that observed in human trabecular meshwork cells. In contrast, the relative amounts of 6-keto-PGF1 alpha and PGF2 alpha were reversed compared with the human cells. The MTM cells produced increased amounts of PGE2 in response to treatment with bradykinin, platelet activating factor, and A-23187. Dexamethasone caused a dose-dependent inhibition of PGE2 production with 50% inhibition by 10(-8) M, although this response was variable.     

Effects of exogenous prostanoids on the proliferation of osteoblast-like cells in vitro

The effects of several prostaglandins on the proliferation of secondary cultures of osteoblast-like cells, as measured by the incorporation of [3H]-thymidine into DNA and total DNA content of the cultures, were studied. PGE2 in the concentration range of 10(-8) to 10(-5) M caused a direct, dose-related stimulation of proliferation, while PGF2 alpha and PGD2 were less effective. PGA2 and 6-keto-PGF1 alpha were inactive in the osteoblasts in concentrations of 10(-7) to 10(-6) M. A similar stimulation profile was observed for the induction of ornithine decarboxylase (ODC, L-ornithine decarboxy-lyase, EC 4.1.1.17): the order of potency of the different prostaglandins in the induction of the ODC activity was PGE2 greater than PGF2 alpha = PGD2; again, PGA2 and 6-keto-PGF1 alpha were without effect in concentrations up to 10(-6) M. These results show that the primary prostaglandins, in order of potency PGE2 greater than PGF2 alpha = PGD2, can have a direct, stimulatory effect on the proliferation of osteoblasts, which is closely related to the induction of ODC activity.     

Prostacyclin induces a surprising long-lasting motility in quiescent uterine strips (indomethacin-treated) isolated from ovariectomized rats

Dose-response curves for several prostaglandins (PGI2; PGD2; PGF2 and PGE2); BaCl2 or prostaglandin metabolites (15-keto-PGF2 alpha; 13,14-diOH-15-keto-PGF2 alpha; 6-keto-PGF1 alpha and 6-keto PGE1 in quiescent (indomethacin-treated) uterine strips from ovariectomized rats, were constructed. All PGs tested as well as BaCl2, triggered at different concentrations, evident phasic contractions. Within the range of concentrations tested the portion of the curves for the metabolites of PGF2 alpha was shifted to the right of that for PGF2 alpha itself; the curve for 6-keto-PGF1 alpha was displaced to the right of the curve for PGI2 and that for 6-keto-PGE1 to the left. It was also demonstrated that the uterine motility elicited by 10(-5) M PGF2 alpha and its metabolites was long lasting (more than 3 hours) and so it was the activity evoked by PGI2;6-keto-PGF1 alpha and BaCl2, but not the contractions following 6-keto-PGE1, which disappeared much earlier. The contractile tension after PGF2 alpha; 15-keto-PGF2 alpha; 13,14-diOH-15-keto-PGF2 alpha and PGI2, increased as time progressed whilst that evoked by 6-keto-PGF1 alpha or BaCl2 fluctuated during the same period around more constant levels. The surprising sustained and gradually increasing contractile activity after a single dose of an unstable prostaglandin such as PGI2, on the isolated rat uterus rendered quiescent by indomethacin, is discussed in terms of an effect associated to its transformation into more stable metabolites (6-keto-PGF1 alpha, or another not tested) or as a consequence of a factor which might protects prostacyclin from inactivation.     

A radioimmunoassay for 6-keto-prostaglandin F1alpha

A radioimmunoassay for 6-keto-prostaglandin F1alpha has been developed. The assay is accurate and sensitive but since the antiserum cross-reacts 5-10% with prostaglandins (PGs) of the E and F series, solvent extraction and thin layer chromatography are required for absolute specificity. The assay has been validated by comparison with a radiochemical assay and by the use of an inhibitor of 6-keto PGF1alpha formation, 15-hydroperoxy arachidonic acid. 6-Keto PGF1alpha was found to have a low cross reaction with antisera directed against PGE2, PGF2alpha and thromboxane B2.     

Concentrations of prostaglandins E2, F2 alpha and 6-keto-prostaglandin F1 alpha in the utero-ovarian venous plasma of nonpregnant and early pregnant ewes

The effect of pregnancy on concentrations of prostaglandins E2, F2 alpha and 6-keto-prostaglandin F1 alpha (PGE2, PGF2 alpha and 6-keto-PGF1 alpha) in utero-ovarian venous plasma was examined in ewes on Days 10 through 14 after estrus, an interval which includes the critical period for maternal recognition of pregnancy. The utero-ovarian vein ipsilateral to a corpus luteum was catheterized on Day 9 or 10 in 6 pregnant and 8 nonpregnant ewes. Five blood samples were collected at 30-min intervals for 2 h beginning at 0500 and 1700 h daily. Sampling began at 0500 h on the day after catheterization. The mean and variance within each 2-h collection period were calculated for each ewe. The natural logarithm of the variance in each collection period (ln variance) was used as an estimate of the fluctuations in secretory activity by the endometrial-conceptus complex. Patterns of the mean concentrations of PGE2 were different between pregnant and nonpregnant ewes (P less than 0.01); PGE2 being higher in the pregnant ewes beginning on Day 13. There was a trend for the patterns of ln variance in PGE2 to differ (P less than 0.1) with pregnancy status over the entire period; ln variance was greater in pregnant ewes beginning on Day 13. The patterns of the mean concentrations and ln variances for PGF2 alpha and 6-keto-PGF1 alpha did not differ between pregnant and nonpregnant ewes. There were significant increases in both of these prostaglandins over time, independent of pregnancy status (P less than 0.01). The association of higher concentrations of PGE2 in utero-ovarian venous plasma with early pregnancy is consistent with the hypothesis that PGE2, originating from the uterus and/or conceptus, is one factor involved in maintenance of the corpus luteum of pregnancy.     

The effect of partial outlet obstruction on prostaglandin generation in the rabbit urinary bladder

Partial outlet obstruction of the urinary bladder has been demonstrated to induce specific dysfunctions in cellular and sub-cellular membrane structures within the bladder's smooth muscle and mucosal compartments. Recent studies have linked these membrane dysfunctions to alterations in phospholipid metabolism leading to mobilization of free arachidonic acid, the precursor for synthesis of prostaglandins (PG). The purpose of this study was to determine if partial outlet obstruction of the urinary bladder induces changes in the capacity of bladder smooth muscle and mucosa to generate PG. PG were isolated from control and partially obstructed urinary bladder smooth muscle and mucosa of male New Zealand White (NZW) rabbits. PG concentrations (PGE2, PGF2alpha and PGI2, as its stable metabolite 6-keto-PGF1alpha) were determined after 30 minute incubations using enzyme-linked immunoassay (ELISA) kits. In both control and obstructed rabbit urinary bladders, PG generation was significantly higher in isolated mucosa than muscle tissues. A significantly higher concentration of PGF2alpha, and 6-keto-PGF1alpha was measured in obstructed muscle tissue relative to controls. The concentration of 6-keto-PGF1alpha was also significantly higher than the concentrations measured for PGE2 and PGF2alpha in both control and obstructed smooth muscle samples. The generation of PGE2 was significantly higher in rabbit urinary bladder mucosa than either PGF2alpha or 6-keto-PGF1alpha in both control and obstructed samples. The capacity of obstructed mucosal tissue to generate 6-keto-PGF1alpha was significantly higher than control tissue, while no significant differences in PGE or PGF2alpha generation were noted. These data suggest obstruction of the urinary bladder induce specific elevations in PG in both smooth muscle and mucosal tissues.     

Increased prostaglandin concentrations in the cervical mucus of pregnant women with bacterial vaginosis.

Microorganisms associated with bacterial vaginosis are commonly recovered from the amniotic fluid and chorion-amnion of patients who deliver prematurely. Bacteria closely related to those causing bacterial vaginosis may play a role in the initiation of uterine contractions, ripening of the cervix and weakening of the fetal membranes by stimulating prostaglandin synthesis. In the present investigation, cervical mucus was collected by brush from early pregnant women with and without bacterial vaginosis. The concentrations of PGE2, PGF2 alpha and 6-keto-PGF1 alpha were determined in the mucus samples by methyl oximation and then radioimmunoassay, utilizing antibodies raised against oximated prostaglandins. It was found that the concentration of PGE2 and PGF2 alpha was significantly higher in the mucus of women with bacterial vaginosis compared with healthy women. The concentration of 6-keto-PGF1 alpha was similar in both study groups. All patients had been instructed to abstain from sexual intercourse for 24 hours before sampling. However, it may be that women with high concentrations in their mucus may have had intercourse anyway. However, it is fairly well possible that the significant differences in the PGE2 and PGF2 alpha values are causally related to the higher rate of preterm labor in women with the commonplace infection of bacterial vaginosis.     

Mechanisms involved in the stimulation by cycloheximide of prostaglandin production in the guinea-pig uterus

Cycloheximide produced a large increase in prostaglandin (PG) E2 output and smaller increases in PGF2 alpha and 6-keto-PGF1 alpha when superfused over the guinea-pig uterus for 20 min. This stimulation of the outputs of these 3 PGs by cycloheximide did not require extracellular calcium. TMB-8 (an intracellular calcium antagonist) had no effect on the stimulation of PGE2 output by cycloheximide, but it completely prevented the stimulation of PGF2 alpha and 6-keto-PGF1 alpha outputs. W-7 (a calmodulin antagonist) had no effect on the stimulation of PGE2 and PGF2 alpha outputs by cycloheximide, but it partially reduced and delayed the stimulation of 6-keto-PGF1 alpha output. Neomycin (a phospholipase C inhibitor) did not prevent the increases in PGE2 and 6-keto-PGF1 alpha outputs produced by cycloheximide. However, neomycin (5 and 10 mM, but not 1 mM) inhibited the small increases in PGF2 alpha caused by cycloheximide. On its own, neomycin produced a dose-dependent, transient increase in 6-keto-PGF1 alpha output without affecting the outputs of PGF2 alpha and PGE2. It is concluded that different mechanisms are involved in the processes by which cycloheximide stimulates the syntheses of PGE2, PGF2 alpha and 6-keto-PGF1 alpha in the guinea-pig uterus.     

Improvement of radioimmunoassays for prostaglandins in bovine blood plasma and their application to monitor reproductive functions

Efficient RIA procedures are required for determination of prostaglandins (PGF(2alpha), PGE(2), PGI(2) and their metabolites) in bovine blood plasma to elucidate their significance in reproductive endocrinology. A new rapid efficient prepurification was developed using commercial octadecyl silicagel cartridges. Prepurification is especially necessary for the determination of 13,14-dihydro-15-keto-PGE(2) (PGEM). After prepurification, PGEM was first converted into the more stable 13,14-dihydro-15-keto-PGA(2) (PGAM) and measured in a RIA-system for PGAM. For PGF(2alpha), 13,14-dihydro-15-keto-PGF(2alpha) (PGFM), PGE(2) and 6-keto-PGF(1alpha) direct tests using 50 mul plasma per tube were elaborated. The validity of the tests was monitored by high performance liquid chromatography radioimmunoassay (HPLC RIA ). Infusion studies using PGF(2alpha) and PGE(2) showed that about 10% of these hormones remained unmetabolized after the first passage through the lungs. The biological half life of the metabolites PGFM and PGEM in bovines was estimated to be 4 min. Thus, PGFM and PGEM measurements in the peripheral circulation reflect even short-term secretory changes of PGF(2alpha) and PGE(2). During the infusion of PGF(2alpha) the levels of progesterone decreased but were not affected by PGE(2). Both prostaglandins caused increased oxytocin secretion. In the cow peripartum first PGEM elevations were measured 5 to 8 d ante partum, whereas PGFM increased 1 to 2 d ante partum. Then both prostaglandins increased simultaneously until parturition. In the postpartal phase PGFM was higher than PGEM, and both prostaglandins remained elevated for several days. Prostacyclin levels remained unchanged during the peripartal period.     

Liquid chromatographic-mass spectrometric determination of cyclooxygenase metabolites of arachidonic acid in cultured cells

A liquid chromatographic-electrospray ionization-mass spectrometric (LC-ESI-MS) technique was developed to simultaneously determine the cyclooxygenase metabolites of arachidonic acid (6-keto-PGF(1alpha), PGD(2), PGE(2), PGF(2alpha), and PGJ(2)) produced by cultured cells. Samples were separated on a C(18) column with water-acetonitrile mobile phase, ionized by electrospray, and detected in the positive mode. Selected ion monitoring (SIM) of m/z 353, 335, 335, 319, and 317 were used for quantifying 6-keto-PGF(1alpha), PGD(2), PGE(2), PGF(2alpha), and PGJ(2), respectively. Prostaglandins were detected at concentrations as low as 1 pg (S/N=3) on the column. The method was used to determine the production of PGs from bovine coronary artery endothelial cells (ECs) and human prostate cancer cells (PC-3) with different degree of invasiveness. Bradykinin (10(-6) M) stimulated a marked increase in the production of 6-keto-PGF(1alpha), PGE(2), and PGF(2alpha) and a small increase of PGD(2) by ECs. 6-Keto-PGF(1alpha) was the major metabolite in these cells. The production of PGE(2) was threefold higher and PGD(2) was twofold higher in PC-3-S (invasive) cells than in PC-3-U (non-invasive) cells.     

Monoclonal antibodies against E- and F-type prostaglandins. High specificity and sensitivity in conventional radioimmunoassays

Polyclonal antisera against prostaglandins (PGs) are widely used for the assessment of the biological role of these mediators, but even the most specific contain antibodies against the major metabolites and degradation products of the haptens employed. To overcome this inherent problem we produced monoclonal antibodies (mAs) against PGE2, PGF2 alpha and 6-keto-PGF1 alpha using the somatic cell hybridization technique. The mAs against 6-keto-PGF1 alpha and PGF2 alpha proved to be highly specific, but allowed only for moderate detection limits (1-2 ng) in conventional fluid phase radioimmunoassays (RIAs). One of the mAs against PGE2 permitted a 100-fold improvement in the detection limit while being almost devoid of cross-reactivity with metabolites and other structurally related PGs. These results show that highly specific mAs against PGs can be produced to improve the available RIA technique for PG quantification.     

Effects of nitrogen dioxide exposure on the contents of prostaglandins and thromboxane B2 in broncho alveolar lavage

Effects of 10 ppm nitrogen dioxide (NO2) exposure on the contents of prostaglandins (PGs) and thromboxane (TX) B2 in bronchoalveolar lavage (BAL) of rats were studied. In the BAL of normal rats, the amounts of PGs and TXB2 in the whole lavage were 6-keto-PGF1 alpha (38.0 +/- 6.4 ng) greater than TXB2 (11.8 +/- 4.0 ng) greater than PGF2 alpha (5.7 +/- 1.6 ng) much greater than PGE (0.5 +/- 0.3 ng). Rats were exposed to NO2 for 1,3,5,7 and 14 days. The NO2 exposure decreased in the level of 6-keto-PGF1 alpha by about 35% throughout the exposure. The level of TXB2 was higher in the day 5 exposure group (155%). The contents of PGF2 alpha and PGE first, decreased and then transiently increased on days 3 and 5. PG 15-hydroxy-dehydrogenase activity of lung homogenate decreased correspondingly on day 3 and 5. Then the contents PGF2 alpha and PGE decreased on day 7 and 14. 6-keto-PGF1 alpha and TXB2 are stable metabolites of PGI2, a strong bronchorelaxant and TXA2, a strong bronchoconstrictor respectively. Therefore the results suggested that the decrease in 6-keto-PGF1 alpha, a major prostanoid in the BAL and the increase in TXB2 may correlate with broncho constriction by NO2 exposure.     

Effects of indomethacin, prostaglandin E2, prostaglandin F2 alpha and 6-keto-prostaglandin F1 alpha on hatching of mouse blastocysts

The present study has been performed to investigate how PGs would participate the hatching process. Effects of indomethacin, an antagonist to PGs biosynthesis, on the hatching of mouse blastocysts were examined in vitro. Furthermore, it was studied that prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha) or 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were added to the culture media with indomethacin. The hatching was inhibited by indomethacin yet the inhibition was reversible. In the groups with indomethacin and PGE2, no improvement was seen in the inhibition of hatching and the inhibition was irreversible. In the groups with indomethacin and PGF2 alpha, inhibition of hatching was improved in comparison with the group with indomethacin. In the groups with indomethacin and 6-keto-PGF1 alpha, no improvement was seen. The above results indicated that PGF2 alpha possibly had an accelerating effect on hatching and a high concentration of PGE2 would exert cytotoxic effect on blastocysts.     

In vivo levels of prostaglandin F2 alpha, E2 and prostacyclin in the corpus luteum of pregnant and pseudopregnant rats

Prostaglandin F2 alpha (PGF2 alpha) is a well-known luteolytic factor in the rat corpus luteum. To investigate a possible luteal origin of PGF2 alpha, measurements of this prostaglandin were performed in different luteal tissues in vivo. Prostaglandin E2 (PGE2) and the stable metabolite of prostacyclin, 6-keto-PGF1 alpha, were assayed simultaneously. Corpora lutea of different ages from 57 pregnant and pseudopregnant rats (mated with sterile males) were rapidly excised, dissected in 0 degree C indomethacin solution, homogenized, and extracted for prostaglandins with solid-phase extraction cartridges. Prostaglandins were determined by radioimmunoassay. Plasma levels of progesterone and 20 alpha-dihydroprogesterone were also monitored. In the adult pseudopregnant rat model, luteolysis occurs at Day 13 +/- 1, and maximal levels of all three prostaglandins were detected on Day 13 of pseudopregnancy: 0.40 +/- 0.02, 2.6 +/- 0.29, and 1.76 +/- 0.24 pmol/mg protein (mean +/- SEM, n=7) for PGF2 alpha, PGE2, and 6-keto-PGF1 alpha respectively. In pregnant rats, on the corresponding day, levels were considerably lower: 0.15 +/- 0.02, 0.90 +/- 0.13, and 0.50 +/- 0.06 pmol/mg protein (mean +/- SEM, n=9, p less than 0.0001), respectively. Luteal levels in pregnant rats showed a continuous decline on Days 13 and 19 for all prostaglandins measured, whereas in pseudopregnant rats an increment of PGF2 alpha was noted between Days 7 and 13 and remained high on Day 19. PGE2 closely followed levels of PGF2 alpha, but at a 5- to 10-fold higher level. The coefficient of correlation between PGF2 alpha and PGE2 in the luteal compartment of both models was 0.87 (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)