Termination of early pregnancy by a single-dose 3.0 mg 15-methyl PGF2α methyl ester vaginal suppository

The abortifacient effect of a single-dose, long-acting vaginal suppository containing 3.0 mg of 15-methyl PGF_2α methyl ester was investigated in 104 early pregnancies. The pregnancy was terminated in 91 per cent of the cases. The abortion was uncomplicated in 79 patients, while 12 patients experienced prolonged bleeding.In 21 uncomplicated cases, Vabra® curettage done 4 weeks after therapy revealed necrotic residual tissue in 16 patients and nonspecific endometritis in 20 patients. Residual tissue was found in about 50 per cent of the patients curettaged after 1st menstruation, but no residua was found after 2nd menstruation.In patients with prolonged bleeding, substantial amounts of necrotic residual tissue was found in all patients curettaged 4 weeks after therapy. The decline of serum hCG and plasma progesterone levels was significantly slower in these patients as compared with uneventful abortions.     

Disappearance of prostaglandins F2α and 15-methyl F2α from amniotic fluid as measured by radioimmunoassay

A sensitive and relatively specific radioimmunoassay for 15 (S) 15 methyl prostaglandin F_2α was used to determine the levels of the drug in amniotic fluid after it had been injected intra-amniotically for termination of second trimester pregnancy. The disappearance of the free acid (tham salt) and methyl ester of the prostaglandin analogue were similar. The results of this preliminary study suggest that the drug rapidly equilibrates in the fluid and this is followed by a slow removal from the amniotic sac. A comparison with a similar study with PGF_2α, revealed that the analogue had a longer half-life in the amniotic fluid.     

Effects of PGF2α and PGF2α, 1–15 lactone on the corpus luteum and on early pregnancy in the rhesus monkey

The effects of prostaglandin (PG)F_2α and PGF_2α, 1–15 lactone were compared in luteal phase, non-pregnant and in early pregnant rhesus monkeys. Animals treated with either PG after pretreatment with human chorionic gonadotropin (hCG) had peripheral plasma progesterone concentrations that were not statistically different from those in animals treated with hCG and vehicle. However, menstrual cycle lengths in monkeys treated with PGF_2α, 1–15 lactone were significantly (P <0.02) shorter than those in vehicle treated animals. In the absence of hCG pretreatment, plasma progesterone concentrations were significantly (P <0.008) lower by the second day after the initial treatment with either PGF_2α or PGF_2α, 1–15 lactone than in vehicle treated monkeys. Menstrual cycle lengths in monkeys treated with either PG were significantly (P <0.04) shorter than those in animals treated with vehicle. There were no changes in plasma progesterone concentrations in early pregnant monkeys treated with PGF_2α, and pregnancy was not interrupted. In contrast, plasma progesterone declined and pregnancy was terminated in 5 of 6 early pregnant monkeys treated with PGF_2α, 1–15 lactone. These data indicate that PGF_2α, 1–15 lactone decreases menstrual cycle lengths in non-pregnant rhesus monkeys. More importantly, PGF_2α, 1–15 lactone terminates early pregnancy in the monkey at a dose which is less than an ineffective dose of PGF_2α.     

Induced abortion in the 8–9th week of pregnancy with vaginally administered 15-methyl PGF2α methyl ester

15(S)15-methyl PGF_2α methyl ester was self-administered vaginally to terminate pregnancy in 42 women in the 8–9th week of gestation. Ten patients received a total of 6 mg of the compound over 15 hours (Group I) while the remaining 32 patients received 5.5 mg of the prostaglandin compound during a shorter period of time or 9 hours (Group II). If parts of the conceptus were expelled during treatment, surgical intervention was excluded. All patients were followed closely after treatment with repeated serum HCG assays and clinical examinations. All patients in Group II and eight out of ten patients in Group I aborted following treatment. In 33 of the 42 patients, the serum HCG levels and the clinical course following the expulsion of the conceptus indicated that abortion was complete. Gastro-intestinal side effects were minimal if anti-diarrheic agents were given prophylactically. The incidence of uterine pain was variable but could in most cases be controlled by oral or rectal administration of analgetics. The results of this study suggest that the use of this compound for termination of pregnancy may be safely extended through the 9th week of gestation and in certain cases be an alternative to the normal operative procedure.     

Effect of PGF2α and 15(S)-15-methyl PGE2 methyl ester on feline generalized penicillin epilepsy

The effect of PGF_2α and 15(S)-15-methyl PGE₂ methyl ester on transient generalized epilepsy in the cat induced by penicillin was examined. Epileptic activity before and after administration of the prostaglandins by several routes was determined from continuous EEG recordings and expressed in epileptic bursts per min. The PGE₂ analogue given in single non-toxic doses (1.6–3 μg/kg) by intramuscular or intravenous routes at the peak of epileptic activity significantly reduced epileptic activity for up to four hours. Subcutaneous administration was less effective. PGF_2α given by the intramuscular route (0.3 mg/kg) also markedly reduced the number of epileptic bursts. Increasing the dosage 4-fold almost completely suppressed epileptic activity. Intracarotid infusion of PGF_2α for one hour (10 μg/min) almost abolished all epileptic activity. Neither prostaglandin given in non-toxic doses induced EEG abnormalities in non-epileptic cats. Toxic doses of the E₂ analogue (>16 μg/kg) caused bilaterally synchronous high voltage slow wave activity. It is concluded that these prostaglandins reduce penicillin epilepsy in the cat. The findings are consistent with either a direct excitatory action on neurones of the medial reticular formation or antagonism of the depressant action of norepinephrine on Purkinje cells.     

Effect of PGF2α and 15(S)-15-methyl PGE2 methyl ester on feline generalized penicillin epilepsy

The effect of PGF_2α and 15(S)-15-methyl PGE₂ methyl ester on transient generalized epilepsy in the cat induced by penicillin was examined. Epileptic activity before and after administration of the prostaglandins by several routes was determined from continuous EEG recordings and expressed in epileptic bursts per min. The PGE₂ analogue given in single non-toxic doses (1.6–3 μg/kg) by intramuscular or intravenous routes at the peak of epileptic activity significantly reduced epileptic activity for up to four hours. Subcutaneous administration was less effective. PGF_2α given by the intramuscular route (0.3 mg/kg) also markedly reduced the number of epileptic bursts. Increasing the dosage 4-fold almost completely suppressed epileptic activity. Intracarotid infusion of PGF_2α for one hour (10 μg/min) almost abolished all epileptic activity. Neither prostaglandin given in non-toxic doses induced EEG abnormalities in non-epileptic cats. Toxic doses of the E₂ analogue (>16 μg/kg) caused bilaterally synchronous high voltage slow wave activity. It is concluded that these prostaglandins reduce penicillin epilepsy in the cat. The findings are consistent with either a direct excitatory action on neurones of the medial reticular formation or antagonism of the depressant action of norepinephrine on Purkinje cells.     

Laminaria augmentation of intra-amniotic PGF2α for midtrimester pregnancy termination

In our hands, intra-amniotic PGF₂α 40 mg for midtrimester pregnancy termination had a mean infusion to abortion interval of 29.4 hr. However, pretreatment of 230 patients with laminaria tents inserted 14–18 hr before PGF₂α infusion resulted in a dramatically reduced time to abortion (14.3 hr mean) with a low incidence of gastrointestinal and other side effects. Laminaria tents inserted at the same time as PGF₂α infusion in 26 patients also resulted in reduced time to abortion (18.6 hr mean). In the laminaria pretreated group, the infusion to abortion interval was indirectly related to the number of laminaria inserted and not to the nulliparous or parous state. Although we have made significant strides in shortening the abortion interval in the hospital, retained placentae and blood loss persist as problems related to the use of prostaglandin for abortion.     

Prostaglandin F2α (PGF2α) and prolactin secretion in rats

Plasma prolactin and F-prostaglandins (PGF) were measured in anesthetized male Sprague-Dawley rats before and at 15, 30, 45 and 60 minutes following i.v. injection of either PGF_2α (4 mg/kg), chlorpromazine, 1 mg/kg or chlorpromazine (1 mg/kg) after pretreatment with i.p. indomethacin (2 mg/kg). Following PGF_2α administration, plasma prolactin levels increased significantly only at 15 and 30 minutes in spite of extremely high PGF levels throughout 60 minutes. Besides the expected rise in plasma prolactin, chlorpromazine caused a transient but statistically significant increase in PGF. Indomethacin blocked the chlorpromazine-induced PGF rise but not prolactin increase. Animals stressed with ether anesthesia showed elevation of plasma prolactin, which was not blocked by indomethacin although PGF concentration fell. These results indicate that PGF_2α can stimulate prolactin release. This effect does not appear to be physiologic since very high PGF levels are required. Furthermore, blockade of prostaglandin synthesis by indomethacin does not prevent the release of prolactin in response to chlorpromazine or stress. Our findings do not support a possible role of PGFs as intermediaries in prolactin release. However, it is possible that PGFs may work through other mechanisms not investigated in our study.     

Changes in the metabolism of PGE1 and PGF2α in rat placenta during pregnancy

The metabolism of PGE₁ and PGF_2α were studied in an in vitro system using placentae from 11-day pregnant rats. PGE₁ was metabolized faster than PGF_2α. The same system was employed to study the quantitative metabolism of these prostaglandins at various stages of pregnancy in the rat. Results of these investigations showed that metabolism became maximal between days 9–12 and between days 15–22 of gestation. On days 12–15 of pregnancy, metabolism decreased, and was at its lowest point on day 14. Maximum prostaglandin metabolism during the sensitive period of days 9–12 of gestation may act as a protective device against the detrimental effects of prostaglandin. Possible correlation of prostaglandin regulation with hormonal balance is discussed.     

PGE2 and PGF2α release by human peritoneal macrophages in endometriosis

Objective: To test for differences in the amount and activity of peritoneal macrophages present in the peritoneal fluid of women with, and without endometriosis using prostaglandin release by macrophages in culture as a marker.Patients: Women of reproductive age undergoing laparoscopy for infertility or chronic pelvic pain with postoperative diagnosis of endometriosis and women undergoing laparoscopy for sterilization.Methods: Peritoneal fluid was aspirated during laparoscopy, volume was recorded, macrophages were isolated via a Ficoll Paque gradient and kept in primary culture. PGE₂ and PGF_2α release of the cells were measured before and after stimulation with zymosan.Results: Women with endometriosis had significantly more peritoneal macrophages than controls. Peritoneal macrophages of women with endometriosis released significantly more PGE₂ than those of the control group: 8.4 ± 2.0 versus 1.4 ± 0.4 ng/ml/10⁶cells (mean ± SEM, p=0.0005) and PGF_2α : 10 ± 4.3 (endometriosis) versus 1.8 ± 0.4 (control) ng/ml/10⁶cells (mean ± SEM, p = 0.045).Conclusion: There is a significant increase in the amount of prostaglandins released by peritoneal macrophages from women with endometriosis. These prostaglandins might alter uterine and tubal contractility, thereby affecting fertility.     

Induction of second trimester abortion: Comparison between vaginal 15-methyl-PGF2α methyl ester and intra-amniotic PGF2α

The efficiency and acceptability of a single-dose, long-acting vaginal suppository containing 3.0 mg of 15-methyl PGF_2α methyl ester was compared with intra-amniotic administration of 50 mg of PGF_2α in 100 patients with a second trimester pregnancy termination. Within 24 hours, 78 per cent of the patients in the vaginal group and 92 per cent in the intra-amniotic group had aborted. The mean induction-abortion interval was 17.9 hours in the vaginal group and 15.8 hours in the intra-amniotic group.Gastrointestinal side-effects were more frequent, but the procedure was less painful, with vaginal 15-methyl PGF_2α methyl ester than with intra-amniotic PGF_2α.The vaginal route is technically simple for adaptation to large-scale use, but the high frequency of gastrointestinal side-effects still limits the acceptability of 15-methyl PGF_2α methyl ester in vaginal administration.     

Treatment with a single vaginal suppository containing 15-methyl PGF2α methyl ester at expected time of menstruation

Termination of early pregnancy, by vaginal administration of prostaglandin analogues, one to three weeks after the first missed menstrual period, has advantages and disadvantages in comparison with vacuum aspiration. Some of these may be reduced if the patient is treated earlier. In the present study the effect and safety of one vaginal administration of 2.5 to 3 mg 15-methyl-PGF_2α methyl ester around the expected time of menstruation was evaluated in 16 women exposed to the risk of pregnancy.The overall number of treatment cycles was 35 and pregnancy was confirmed by plasma β-HCG in eight. The treatment resulted in bleeding in all the pregnant cycles while in the nonpregnant ones it only provoked spotting and bleeding did not begin until the expected time of menstruation. Treatment with 2.5 mg 15-methyl-PGF_2α methyl ester resulted in complete abortion in one of three women. If the dose was increased to 3 mg all five treated women aborted. In nonpregnant patients no changes in the levels of estradiol-17β or progesterone at any time during the 24-hour observation period were found. Serum cortisol and prolactin but not TSH levels started to increase two hours after the start of treatment and reached a maximum after five hours. The increase coincided with the onset of uterine pain.Ovulatory cycles as judged from basal body temperature occurred in the first menstrual cycle following treatment in all nonpregnant patients. Although possible to use as a “once a month treatment” it seems preferable since the dose is the same, to postpone treatment until menstruation is delayed for a week or more.     

Intracellular recording of cerebral cortical actions of prostaglandin F2α (PGF2α)

Our reported data on the cortical inhibitory actions of prostaglandin F_2α (PGF_2α) and the diversity of data in the literature on cerebral PG actions are examined here in the light of intracellular recording which provides the requisite membrane data for the first time. Thus, 1) intracellular recording from the cat cerebral cortex is obtained for the actions of PGF_2α and for norepinephrine (NE) and serotonin (5HT). 2) The parallel changes in firing and polarization and the simultaneous transmembrane conductance changes are qualitatively identical for PGF_2α, NE and 5HT. 3) The reduction in firing accompanied by hyperpolarization indicates that PGF_2α, NE and 5HT all inhibit these cells. 4) The ionic species responsible for this inhibition is such that it increased the transmembrane resistance, and this was true for all three. 5) The changes in membrane parameters, identical in direction for PGF_2α and NE, but stronger for the latter, constitute conditions that can lead to competitive inhibition and therefore conote, presumably, actions at the same or related receptors. Such competition with evoked cortical field potentials is shown in the preceding paper.     

Differential effects of probenecid on the levels of endogenous PGF2α and TXB2 in brain cortex

Probenecid in single or repeated doses does not modify levels of PGF_2α and TXB₂ in rat brain cortex. After administration of subconvulsant dose of pentamethylene tetrazone (PMT) PGF_2α increases sharply and rapidly declines subsequently, whereas the elevation of TXB₂ is smaller but of longer duration. After probenecid pretreatment PGF_2α levels do not decline up to 30 minutes after the initial peak and are still elevated after 60 minutes. Levels of TXB₂ tend to be reduced after pretreatment. Differences in transport process or in biosynthetic compartments for these arachidonic acid (AA) metabolites may account for the observed data.     

Immunohistochemical localization of PGF2α receptor in the mouse testis

As a step towards understanding the role of prostaglandin F2 alpha (PGF2 alpha) in male reproductive tract physiology, a rabbit polyclonal antiserum reactive with purified PGF2 alpha receptor (PGF2 alpha-R) was produced. Here we describe the use of this anti-PGF2 alpha-R antiserum in immunohistochemical staining of mouse testis to ascertain which cell types, in vivo, possess immunoreactive PGF2 alpha-R. As an initial control Western blot analysis was performed to show that the anti-PGF2 alpha-R antiserum recognizes only one antigen in the testis, and that this molecule is similar in molecular mass (by PAGE) to the previously described, purified PGF2 alpha-R molecule. Immunohistochemical staining demonstrates that adult mouse testis contains a single subpopulation of cells with PGF2 alpha-R and that subpopulation is the interstitial or Leydig cell subpopulation. Cell and tissue types negative for immunoreactive PGF2 alpha-R include: the capsule (tunica albuginea) and subcapsular stroma, all histologic layers of the vasculature (both venules and arterioles), peritubular stroma, peritubular boundary tissue, spermatogonia, primary and secondary spermatocytes, spermatids, Sertoli cells, and spermatozoa. While the above described localization of PGF2 alpha-R is also seen in rat, there are fewer rat Leydig cells and this subpopulation appears to atrophy and stain less intensely with increasing age of the animal. Preabsorption of the PGF2 alpha-R antiserum with a corpora lutea homogenate acetone powder eliminated immunohistochemical staining of the Leydig cell subpopulation further suggesting that the antigenic determinant detected here is related to that in the ovary (PGF2 alpha-R).     

Laminaria augmentation of intra-amniotic PGF2 for midtrimester pregnancy termination

In our hands, intra-amniotic PGF_2^α 40 mg for midtrimester pregnancy termination had a mean infusion to abortion interval of 29.4 hr. However, pretreatment of 230 patients with laminaria tents inserted 14–18 hr before PGF_2^α infusion resulted in a dramatically reduced time to abortion (14.3 hr mean) with a low incidence of gastrointestinal and other side effects. Laminaria tents inserted at the same time as PGF_2^α infusion in 26 patients also resulted in reduced time to abortion (18.6 hr mean). In the laminaria pretreated group, the infusion to abortion interval was indirectly related to the number of laminaria inserted and not to the nulliparous or parous state. Although we have made significant strides in shortening the abortion interval in the hospital, retained placentae and blood loss persist as problems related to the use of prostaglandin for abortion.     

Blood LH after PGF2α in diestrous and ovariectomized cattle

Two experiments were conducted to determine whether the increased serum LH which occurs within 12 hr after a luteolytic dose of PGF_2α is dependent upon changes in progesterone or estradiol secretion. In the first experiment, exogenous progesterone abolished the increase in serum LH caused by a subcutaneous injection of 25 mg PGF_2α in diestrous heifers, but not in ovariectomized heifers. In the second experiment, progesterone pessaries were removed at 6 hr after a subcutaneous injection of 25 mg PGF_2α. LH remained at pre-PGF_2α values while the pessaries were in place, but began to increase within 1 hr after they were removed. Blood estradiol also remained at pre-PGF_2α values until the pessaries were removed, and began to increase at 2 hr after pessary removal. We conclude that the increase in serum LH within 12 hr after PGF_2α treatment in diestrous cattle is dependent upon withdrawal of progesterone; it is not due to increased serum estradiol.     

Role of progesterone in regulating uteroovarian venous concentrations of PGF2 α and PGE2 during the estrous cycle and early pregnancy in ewes

The role of progesterone in regulation of uteroovarian venous concentrations of prostaglandins F₂ α (PGF₂α) and E₂ (PGE₂) during days 13 to 16 of the ovine estrous cycle or early pregancy was examined. At estrus, ewes were either mated to a fertile ram or unmated. On day 12 postesturus, ewes were laparotomized and a catheter was inserted into a uteroovarian vein. Six mated and 7 unmated ewes received no further treatment. Fifteen mated and 13 unmated ewes were ovariectomized on day 12 and of these, 7 mated and 5 unmated ewes were given 10 mg progesteron sc and an intravaginal pessary containing 30 mg of progesterone. Uteroovarian venous samples were collected every 15 min for 3 h on days 13 to 16 postestrus. Mating resulted in higher mean daily concentrations of PGE₂ in the uterovarian vein than in unmated ewes. Ovariectomy prevented the rise in PGE₂ with day in mated ewes but had no effect in unmated ewes. Progesterone treatment restored PGE₂ in ovariectomized, mated ewes with intact embros. Mating had no effect on mean daily concentrations of PGF₂α or the patterns of the natural logarithm (ln) of the invariance of PGF₂α. Ovariectomy resulted in higher mean concentrations and ln invariances of PGF₂α on day 13 and lower mean concentrations and ln invariances of PGF₂α on days 15 and 16. Replacement with progesterone prevented these changes in patters of mean concentrations and ln variances of PGF₂α following ovariectomy. It is concluded that progesterone regulates the release of PGF₂α from the uterus, maintaining high concentrations while also preventing the occurrence of the final peaks of PGF₂α which are seen with falling concentrations of progesterone. This occurs in both pregnant and non-pregnant ewes. Progesterone is also needed to maintain increasing concentrations of PGE₂ in mated ewes.     

Interactions of prostaglandins with subpopulations of ovine luteal cells. II. Inhibitory effects of PGF2α and protection by PGE2

Purified preparations of ovine large luteal cells were utilized in a series of experiments to test the effects of prostaglandins (PG) E₂ abd F₂α on cell morphology, viability and secretion of progesterone. Luteal cells were allowed to attach to culture dishes overnight before experiments. In the first series of experiments incubation of large steroidogenic cells with PGF₂α for 6 hr resulted in morphological changes including a retraction of the cell cytoplasm and apparent extrusion of cytoplasmic components which became more pronounced after 12 hr. In a second series of experiments, PGF₂α decreased and PGE₂ increased progesterone accumulation in media after 6 hr when media were not replaced during the incubation period, while progesterone accumulation was not different than that observed in control dishes when both prostaglandins were present. Hourly replacement of the media negated the inhibitory effects of PGF₂α but had no effect on the stimulated secretion of progesterone induced by PGE₂. Finally, in incubations without media replacement, PGF₂α induced a dose-dependent decrease in progesterone accumulation while PGE₂ elicited a biphasic response with progesterone secretion increasing from 0.1 ng/ml to maximal levels at 10 ng/ml followed by a dose-dependent decrease at 100 and 1000 ng/ml. These data are compatible with the hypotheses that: 1) luteolysis is initiated, at least in part, by an action of PGF₂α on large luteal cells; and 2) the embryonic signal from the pregnant uterus which rescues the ovine corpus luteum may be PGE₂.     

Corpus luteum susceptibility to prostaglandin F2α (PGF2α) luteolysis in hysterectomized prepuberal and mature gilts

The susceptibility of induced corpora lutea (CL) of prepuberal gilts and spontaneously formed CL of mature gilts to prostaglandin F_2α (PGF_2α) luteolysis was studied. Prepuberal gilts (120 to 130 days of age) were induced to ovulate with Pregnant Mare Serum Gonadotropin and Human Chorionic Gonadotropin (HCG). The day following HCG was designated as Day 0. Mature gilts which had displayed two or more estrous cycles of 18 to 22 days were used (onset of estrus = Day 0). Gilts were laparotomized on Day 6 to 9, their CL marked with sterile charcoal and totally hysterectomized. On Day 20, gilts were injected IM with either distilled water (DW), 2.5 mg PGF_2α or 5.0 mg PGF_2α. An additional group of prepuberal gilts was injected with 1.25 mg PGF_2α, a dose of PGF_2α equivalent, on a per kilogram body weight basis, to the 2.5 mg PGF_2α dose given to the mature gilts. The percentages of luteal regression on Day 27 to 30 for mature and prepuberal gilts given DW, 2.5 mg PGF_2α and 5.0 mg PGF_2α were 0.0 vs 4.4, 43.5 vs 96.8 and 47.7 vs 91.6, respectively; the percentage of luteal regression for the prepuberal gilts given 1.25 mg PGF_2α was 75.1. These results indicate that induced CL of the prepuberal gilt were more susceptible to PGF_2α luteolysis than spontaneously formed CL of the mature gilt and that pregnancy failure in the prepuberal gilt could be due to increased susceptibility of induced CL to the natural luteolysin.