Oviduct response to prostaglandins: Influence of estradiol and progesterone

Oviductal motility was measured in the isthmus of ovariectomized New Zealand rabbits. The effects of estradiol and progesterone on spontaneous motility and on the response of the oviduct to exogenously administered prostaglandin E₁ (PGE₁) and PGF_2α were determined. Estradiol treatment significantly increased both the amplitude (P<0.05) and frequency (P<0.01) of spontaneous contractions. The amplitude of spontaneous activity was less following progesterone treatment than following estradiol treatment (P<0.05). Progesterone treatment increased the duration of oviduct response to PGE₁ (P<0.05). Estradiol treatment had no effect on the response to PGE₁. Increased oviductal activity caused by PGF_2α lasted significantly (P<0.01) longer in ovariectomized, untreated animals than in ovariectomized animals treated with estradiol or progesterone. Progesterone was more effective than estradiol in decreasing the duration of the response to PGF_2α. These effects of steroid hormones on the responsiveness of the oviduct to PGE₁ and PGF_2α could contribute to the physiological control of egg transport. The nadir of ovarian hormone influence, as in the recently ovariectomized animals and as occurs immediately after ovulation, is associated with a high responsiveness of the oviduct to PGF_2α. This could effectively increase isthmic occlusion and prevent the eggs from passing through the oviduct prematurely. The gradual increase in ovarian estradiol and progesterone secretion during the 3 days following coitus could result in decreased responsiveness to PGF_2α and increased responsiveness to PGE₁. These changes might cause relaxation of isthmic tone and allow movement of eggs through the isthmus into the uterus.     

The effect of adrenergic stimulation on urinary prostaglandin E2 and 6 keto PGF1α in man

To evaluate the details of the adrenergic stimulation of urinary prostaglandins in man, ten normal volunteers were given various agonists and antagonists. The effect of 4 hour IV infusions of norepinephrine (NE), NE + phentolamine (PHT), NE + phenoxybenzamine (PHB), NE + prazosin (PZ), isoproterenol (ISO), and PHT alone on urinary PGE₂ and PGI₂ (6 keto PGF_1α) were determined. PGE₂ and 6 keto PGF_1α were measured by radioimmunoassay from 4 hour urine samples. NE stimulated both PGE₂ (196±40 to 370±84 ng/4 hrs/g creatinine and 6 keto PGF_1α(184±30 to 326±36), both p<0.01. In contrast, ISO had no effect on either PGE₂ or 6 keto PGF_1α excretion. Alpha blockade with PHT. PHB, or PZ inhibited the NE induced systemic pressor effect. However, the effect of the alpha blockers on the NE induced stimulation of PGE₂ and 6 keto PGF_1α varied. PHT did not alter the NE stimulated PGE₂ or 6 keto PGF_1α release (370±84 vs. 381±80) PGE₂ and (326±50 vs. 315±40) 6 keto PGF_1α, both p>0.2). PHT alone stimulated only 6 keto PGF_1α. PHB and the specific α₁ antagonist PZ similarly eliminated the NE induced prostaglandin release. These results suggest that adrenergically mediated urinary prostaglandin release in man is via an alpha receptor with α₁ characteristics.     

Radioimmunological and biological measurement of prostaglandins in rabbit urine : Decrease of PGE2 excretion at high NaCl intake

The estimation of prostaglandin (PG) E₂ and of PGF_2α by radioimmunoassay is described in detail. PGE₂ was measured after conversion to either PGB₂ or PGF_2α and the results compared to bioassay. The methods were used to follow the excretion of PGE₂ and PGF_2α after salt loading in rabbits. A marked reduction of PGE₂ levels was observed at high NaCl intake, while PGF_2α excretion remained unchanged.     

PGE2 is a more potent vasodilator of the lamb ductus arteriosus than is either PGI2 or 6 keto PGFα

It has been shown in vitro that the lamb ductus arteriosus forms prostaglandins PGE₂, PGF_2α, 6 keto PGF_1α (and its unstable precursor PGI₂). In this study the relative potencies of these endogenous prostaglandins were investigated on isolated lamb ductus arteriosus preparations contracted by exposure to elevated PO₂ and indomethacin. All the prostaglandins (except PGF_2α) relaxed the vessel. This is consistent with the hypothesis that endogenous prostaglandins inhibit the tendency of the vessel to contract in response to oxygen. Only PGE₂, however, relaxed the vessel at concentrations below 10⁻⁸M. PGI₂ and 6 keto PGF_1α had approximately 0.001 and 0.0001 times the activity of PGE₂. Although PGE₂ has been observed to be a minor product of prostaglandin production in the lamb ductus arteriosus, the tissue's marked sensitivity to PGE₂ might make it the most significant prostaglandin in regulating the patency of the vessel.     

Seminal prostaglandins in men with subnormal sperm motility and therapeutic treatment

The contents of prostaglandins in seminal plasma from a total of 73 men were evaluated. The subjects were grouped as follows: normospermic men, patients with impaired motility, patients with small untreated varicocelle and patients with impaired motility and Kallikrein therapy. Sperm density, morphology and motility were examined. High performance reversed phase liquid chromatography (HPLC) in combination with specific radioimmunoassays were used for the determination of PGE₂, PGI₂ and PGF_2α. There was a significant difference (p < 0, 025; F-test) between the PGI₂ concentrations in patients with impaired motility (5,6 ± 1,4 pg/mg protein) and normal men (8,8 ± 3,7 pg/mg protein). PGE₂ and PGF_2α were significantly different in patients with varicocele (p < 0,025, F-test). Wide ranges of prostaglandins occured in the Kallikrein-group with no significant differences. We conclude that: a) PGI₁ is an additional prostaglandin compound in seminal plasma. b)its measurement may not be useful as diagnostic parameter in subfertile men and c) Kallikrein has no influence on the prostaglandin content in seminal plasma and other seminal parameters as motility, motility index and sperm counts.     

Prostaglandin (PG) analysis in urine of humans and rats by different radioimmunoassays: Effect on PG-excretion by PG-synthetase inhibitors, laparotomy and furosemide

Thw radioimmunological (RIA) determination of prostaglandin (PG) E₂ and of PGF_2α in urine humans and rats is described in detail. After extraction and chromatography PGE₂ was determined by using a PGE specific antibody or by using either PGB or PGF_2α specific antibodies after the respective conversion procedures. The three different RIA procedures were compared to each other. PGF_2α was determined by a specific antibody to PGF_2α. Basal excretion of PGE₂ and of PGF_2α in healthy women on free diet was 9.3 ng/hour ± 0.96 and 18.3 ng/hour ± 2.5 respectively. Furosemide increased the excretion of PGE₂ and of PGF_2α in humans significantly, while PG-excretion rates decreased on indomethacin. In rat urine PGE₂ and PGE_2α increased markedly from 46.2 pg/min ± 9.3 and 27 ± 3.4 to 253.8 ± 43.3 and 108 ± 12.6 pg/min (per one kidney) in the anesthetized-laparotomized animal. This increase was abolished after giving two different PG synthetase inhibitors.     

Synthesis and metabolism of prostaglandins E2, F2α and D2 by the rat gastrointestinal tract. Stimulation by a hypertonic environment in vitro

Whole cell preparations of rat stomach corpus, jejunum, and colon were incubated and the released prostaglandin E₂ (PGE₂), PGF_2α, PGD₂, 15 keto-13,14 dihydro PGE₂, and 15 keto-13,14 dihydro PGF_2α were measured by combined gas chromatography-mass spectrometry. All regions made PGD₂ and possessed a high capacity for producing 15 keto-13,14 dihydro derivatives of both PGE₂ and PGF_2α. Hypertonic sucrose solutions resulted in concentration-dependent increases in prostaglandin release, particularly of PGE₂ and its metabolite. It is suggested that PG's may play a role in the local effects of luminal hyperosomolarity on digestive tract functions.     

In vitro prostaglandin synthesis by human glomeruli and papillae

We have investigated in vitro prostaglandin synthesis by human isolated glomeruli and papillary homogenates and compared the results with those obtained in parallel studies using rat material. Prostaglandins were measured by two methods, namely radiometric high performance liquid chromatography after incubation with ¹⁴C arachidonic acid and radioimmunoassay. The relative abundance of various prostaglandins synthesized by glomeruli was different in man (6 keto PGF_1α > TXB₂ > PGF_2α > PGE₂) and in the rat (PGE₂ TXB₂ > 6 keto PGF_1α). Unidentified peaks eluting between 6 keto PGF_1α and TXB₂ were observed only in rat glomeruli. These peaks were suppressed by indomethacin. Direct radioimmunoassay of prostaglandins in the incubation medium of human glomeruli confirmed the predominance of 6 keto PGF_1α synthesis and showed its stimulation by arachidonic acid, its progressive decrease with time and its linear relationship with glomerular protein at low concentrations. On the contrary, the profile of prostaglandin synthesis by the papilla was similar in man and in the rat, PGE₂ and PGF_2α being the major products in both species. However, related to one mg of protein, papillary synthesis of these two prostaglandins was greater in the rat. These results show that PGI₂ is the major prostaglandin synthesized in human glomeruli and suggest a role for this prostaglandin in glomerular physiology in man.     

Effects of indomethacin, prostaglandin E2, prostaglandin F2α and 6-keto-prostaglandin F1α 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 F_2α (PGF_2α) or 6-keto-prostaglandin F_1α (6-keto-PGF_1α) were added to the culture media with indomethacin. (1) The hatching was inhibited by indomethacin yet the inhibition was reversible. (2) In the groups with indomethacin and PGE₂, no improvement was seen in the inhibition of hatching and the inhibition was irreversible. (3) In the groups with indomethacin and PGF_2α, inhibition of hatching was improved in comparison with the group with indomethacin. (4) In the groups with indomethacin and 6-keto-PGF_1α, no improvement was seen. The above results indicated that PGF_2α possibly had an accelerating effect on hatching and a high concentration of PGE₂ would exert cytotoxic effect on blastocysts.     

The effects of prostaglandins, prostaglandin inhibitors, and oxygen on the closure of the ductus arteriosus, pulmonary arteries and umbilical vessels in vitro

Three prostaglandins (PGF₂α and PGE₁, PGE₂) have been found in maternal and fetal circulation during labour. Two of these prostaglandins (PGF₂α and PGE₂) are present in elevated levels in maternal circulation during labour and their presence in fetal vessels has been shown.These three prostaglandins have been tested for their effects on fetal vessels in vitro (umbilical artery and vein, ductus arteriosus, and smaller pulmonary artery). These vessels were selected as being crucial in the conversion from fetal to extra-uterine circulation in mammalian species. Responses of these vessels to the prostaglandins under varying oxygen regimes have been examined as well as their responses to prostaglandin inhibitors. Activity of vessels of varying gestational ages exposed to PGF₂α was also examined. The following results were obtained:

1. All vessels, with the exception of pulmonary arteries, contracted in the presence of oxygen over the range 20–100mmHg pO₂. At a pO₂ of < 20mmHg the ductus arteriosus remained inactive or dilated. Pulmonary arteries dilated at high pO₂.

2. All vessels contracted in response to exogenous PGF₂α with the exception of the pulmonary arteries which dilated. In the presence of PGF₂α, the umbilical veins dilated under low (< 20mmHg) pO₂ and contracted at higher levels. Contraction also occurred at lower levels after a period of time.

3. Although PGF₂α was capable of causing contraction in the ductus arteriosus at near zero pO₂, oxygen, (or possibly the products of oxygenation), appear to be required for continued contraction in the presence of PGF₂α. A synergistic relationship between oxygen and PGF₂α responses was found as oxygen tensions increased. A synergistic response between PGF₂α and oxygen with umbilical arteries which did not increase with increased pO₂ was also found. Oxygen tension appeared to have little effect on the response of other vessels to PGF₂α.

4. PGE₁ caused dilations in all vessels examined. Such dilations appearing to be independent of the oxygen regime prevailing. However, an increase in oxygen during experiments reversed any dilation caused by the prostaglandins.

5. PGE₂ caused contractions in umbilical vessels which were independent of oxygen. PGE₂ caused contraction of pulmonary arteries. However, in the ductus arteriosus, PGE₂ caused an initial contraction followed by a strong dilation. This dilation became weaker as pO₂ increased.

6. Additions of prostaglandin inhibitors (Naproxen and Indomethacin) to the bathing solution in which the ductus arteriosus and umbilical arteries were contracting (in response to PGF₂α, or oxygen alone) caused a decrease in contractions, and sometimes a slight decrease when the vessel had been pretreated with PGF₂α suggesting a possible need for endogenously synthesised prostaglandins for the maintenance of oxygen mediated contractions (in vivo).

7. Vessels responsed to PGF₂α at an early gestational age. A role for prostaglandins and oxygen in the closure of fetal vessels is discussed.

     

Radioimmunoassay of prostaglandins E1, E2, and F2α in unextracted plasma, serum and myocardium

A radioimmunoassay procedure for the determination of PGE₁, PGE₂, and PGF₂α is presented. The procedure involves the pre-precipitation of each prostaglandin specific antiserum with the precipitating antisera (ARGG), and the use of these antisera mixtures in assaying for PGE₁, PGE₂, and PGF₂α. Applicability of the methods to unextracted plasma, serum and myocardial homogenate has been demonstrated through tests of specificity, recovery, reproducability and parallelism. A mathematical correction for cross-reactivity between PGE₁ and PGE₂, and their opposing antisera is given. To demonstrate the utility of the methodology in differentiation of experimental variables, prostaglandin concentrations in unincubated serum, incubated serum, and the rate of prostaglandin production in serum of dogs are given.     

Prostaglandin synthesis by rheumatoid synovium and its stimulation by colchicine

The synthesis of prostaglandins by rheumatoid synovial tissue in organ culture was studied utilizing radioimmunoassay, with antisera to PGB₁, PGF_1α and PGF_2α. It was established that PGE₂ and PGF_2α were the major prostaglandins formed by analyses of culture media with the two antisera to PGF, before and after alkali treatment. Indomethacin at 5 μg/ml suppressed prostaglandin synthesis, usually to <1% of control cultures. Colchicine, 0.1 μg/ml resulted in marked stimulation of prostaglandin synthesis, in some cases over 10 fold. It is suggested, because of the colchicine effect, that the state of the microtubules may regulate the rate of prostaglandin biosynthesis. It is possible that prostaglandin E₂ produced by rheumatoid synovia may contribute to the pathogenesis of the inflammatory reaction and lead to destruction of juxta-articular bone in rheumatoid arthritis.     

Relationships among mammalian gonadotropin-releasing hormone, prostaglandins, and sex steroids in the brain of the crested newt, Triturus carnifex

The present study was carried out to evaluate the in vitro brain release of prostaglandin F_2α (PGF_2α), prostaglandin E₂ (PGE₂), androgens, and 17β-estradiol in male and female crested newt, Triturus carnifex, during three different periods of the annual sexual cycle; in addition, the effects of mammalian gonadotropin-releasing hormone (mGnRH), PGF_2α, and PGE₂ on prostaglandins and steroids release by the brain were evaluated during the same periods. In brain incubations of both sexes, PGF_2α and estradiol were higher during postreproduction, while PGE₂ and androgens were higher during reproduction. In both sexes, mGnRH increased PGF_2α and estradiol during postreproduction, and PGE₂ during reproduction; PGF_2α increased estradiol secretion during postreproduction. Only in the male, did both mGnRH and PGE₂ increase androgens during reproduction. It could be suggested that in Triturus carnifex, the regulation of the reproductive activity in the central nervous system (CNS) depends on the relationships among mGnRH, prostaglandins and steroids. In particular, PGF_2α and PGE₂ seem to play different roles in the CNS of the newt: PGF_2α is involved in the postreproductive processes, through estradiol secretion, while PGE₂ in the reproductive ones (through androgens secretion?).     

Prostaglandins and thromboxanes in amniotic fluid during rivanol-induced abortion and labour

Abortion or delivery were induced by extra-amniotic instillation of Rivanol during the second trimester in twelve patients and during the third trimester in two patients with fetal death and one patient with fetal acrania. Serial sampling of amniotic fluid was performed through a transabdominal catheter and the levels of free arachidonic acid (AA), prostaglandin F₂α (PGF₂α), prostaglandin E₂ (PGE₂), 6-keto-prostaglandin F₁α (6-keto-PGF₁α) and thromboxane B₂ (TXB₂) were determined. The levels of AA, PGF₂α, PGE₂, 6-keto-PGF₁α and TXB₂ in amniotic fluid increased significantly during induction with the exception of AA in fetal death which was high and remained constant during induction. Furthermore, PGF₂α, 6-keto-PGF₁α and TXB₂ were all significantly correlated to AA.These observations suggested that free AA is released during Rivanol-induction of abortion and labour giving an increased synthesis of PGF₂α, PGE₂ prostacyclin and thromboxane A₂ in the fetal membranes and the decidua but not in the fetus. This increase might be relevant for the initiation and progress of abortion and labour in these patients.     

Tracheobronchial irritancy of inhaled prostaglandins in the conscious cat

A novel test was developed to measure the tracheobronchial irritant activity of inhaled prostaglandins. Conscious restrained cats were challenged with seperate aerosols of PGE₁, PGF_2α, acetylcholine or isoprenaline. All of the aerosols except isoprenaline caused coughing in a concentration related manner. Tolerance developed very quickly to the tracheobronchial irritation and lasted 1–2 days for PGE₁ and less than 1 day for PGF_2α and acetylcholine. When a 3 day interval between each aerosol challenge was used, PGF_2α was approximately 700 times more potent than acetylcholine as a tracheobronchial irritant. The highest PGE₁ aerosol concentration (500 μg/ml) also caused sedation, diarrhoea and salivation. This test probably provides a useful method for evaluating the tracheobronchial irritant activity of potential prostaglandin bronchodilator analogues and for investigating the mechanism of action of prostaglandin induced tracheobronchial irritancy.     

Prostaglandin synthesis by rheumatoid synovium and its stimulation by colchicine

The synthesis of prostaglandins by rheumatoid synovial tissue in organ culture was studied utilizing radioimmunoassay, with antisera to PGB₁, PGF_1α and PGF_2α. It was established that PGE₂ and PGF_2α were the major prostaglandins formed by analyses of culture media with the two antisera to PGF, before and after alkali treatment. Indomethacin at 5 μg/ml suppressed prostaglandin synthesis, usually to <1% of control cultures. Colchicine, 0.1 μg/ml resulted in marked stimulation of prostaglandin synthesis, in some cases over 10 fold. It is suggested, because of the colchicine effect, that the state of the microtubules may regulate the rate of prostaglandin biosynthesis. It is possible that prostaglandin E₂ produced by rheumatoid synovia may contribute to the pathogenesis of the inflammatory reaction and lead to destruction of juxta-articular bone in rheumatoid arthritis.     

Effects of oestradiol, progesterone, hydrocortisone and oxytocin on prostaglandin output from the guinea-pig endometrium maintained in tissue culture

The effects of oestradiol, oxytocin, progesterone and hydrocortisone on prostaglandin (PG) output from guinea-pig endomerium, removed on days 7 and 15 of the oestrous cycle and maintained in tissue culture for 3 days, have been investigated. Oetradiol (3.7 to 3700nM) and oxytocin ( 2 to 200pM) did not stimulate endometrial PGF_2α output, thus not confirming the findings of a previous report (Leaver & Seawright, 1928), nor did they stimulate the outputs of PGE₂ and 6-keto-PGF_1α. In fact, oestradiol (3700nM) inhibited the outputs of PGF_2α, PGE₂ and, to a lesser extent, 6-keto-PGF_1α. Progesterone (3.2 to 3200nM) inhibited the outputsof PGF_2α and PGE₂; hydrocortisone (2.8 to 2800nM) had no effect on endometrial PG output. These findings indicate that the inhibitory effect of progesterone on endometrial PG synthesis and release in the guinea-pig is not due to progesterone having a glucocorticoid-like action. Furthermore, progesterone had no effect on 6-keto-PGF_1α output, suggesting that the mechanisms controlling endometrial PGI₂ synthesis (as reflected by measuring 6-keto-PGF_1α) are different from those controlling endometrial PGF_2α and PGE₂ synthesis.     

Biological activities of 17-phenyl-18,19,20-trinorprostaglandins

In a number of assay ssytems, some 17-phenyl-trinor prostaglandins were similar in activity and potency to the corresponding parent prostaglandin. In others, the 17-phenyl analogs appeared several times more potent. In the hamster antifertility assay, which is considered to measure luteolytic activity, 17-phenyl-18,19,20-trinor prostaglandin F_2α was about 90-times PGF_2α in potency.Rat blood pressure responses to 17-phenyl analogs were significant. The 17-phenyl-trinor PGF_2α pressor potency was 5 times that of PGF_2α. The 17-phenyl-trinor PGE₂ blood pressure response was atypical since a pressor rebound phenomenon followed the expected depressor response. Lastly, 17-phenyl-trinor PGF_2α was more potent than PGF_2α in synchronizing the estrous cycle in beef cows.     

Synthesis of prostaglandins by pig blastocysts cultured in medium containing estradiol or catechol estrogen

Two experiments were conducted to determine the effects of 2-hydroxy-estradiol-17β (2---OH---E₂; 0, 50 and 100 μM) and estradiol-17β (E₂; 0, 25 and 50 μM) on prostaglandin (PG) E and PGF₂α synthesis by day-10 pig blastocysts (day 0 is first day of estrus). Blastocysts were incubated in a modified Krebs-Ringer bicarbonate medium, supplemented with bovine serum albumin (4 mg/ml) and the vitamins and amino acids (essential and nonessential) in Minimum Essential Medium (without phenol red or antibiotics). The incubations were conducted at 39°C for three 2-h periods; the second and third periods included an E₂ or catechol estrogen treatment. Release of PGF₂α into the culture medium decreased (p<0.001) linearly with increasing concentrations of 2---H---E₂ in both periods. Release of PGE was not affected by 2---OH---E₂, therefore 2---OH---E₂ increased (p<0.06) the PGE:PGF₂α. When E₂ was added to the medium, release of PGE was decreased (p<0.01) during the second and third periods. Release of PGF₂α also was decreased (p<0.05) by E₂ during period 2, but E₂ did not alter the PGE:PGF₂α. Content of PGs in blastocysts at recovery was less than 10% of the PGs released in vitro. Therefore, these studies demonstrate effects of both the primary and catechol forms of E₂ on the synthesis of PGE and PGF₂α. Catechol estrogens and E₂ may inhibit PG synthesis and modify the PGE:PGF₂α during the establishment of pregnancy in pigs.     

Bronchial Hyperreactivity to Prostaglandin F2α and Histamine in Patients with Asthma

The influence on airway conductance of inhaled aerosols of prostaglandin F₂α (PGF₂α), histamine, and prostaglandin E₂ (PGE₂) was studied in 10 patients with spirometrically reversible bronchial asthma and in 10 healthy subjects with no history of lung disorder. Both groups responded with bronchoconstriction after inhalation of PGF₂α but the asthmatic patients were about 8,000 times more sensitive to the compound than were the healthy controls. In the patients, but not in the controls, PGF₂α often caused a long-standing decrease in airway conductance with symptoms resembling allergen-provoked asthmatic attacks. On the other hand, the patients showed less than a 10-fold increase in sensitivity to histamine, and the ratio of histamine: PGF₂α doses causing a 50% decrease of airway conductance was 2·6:1 and 2,400:1 in controls and patients respectively. Inhalation of PGE₂ while moderately but consistently increasing airway conductance in controls, had a variable—occasionally slight bronchoconstrictive—effect in patients. The decrease in airway conductance by a given dose of PGF₂α was little modified by the simultaneous inhalation of a 100-times higher PGE₂ dose. It is suggested that endogenous, locally formed PGF₂α may play an important part in the pathogenesis of bronchial asthma.