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.     

Determination of prostaglandin F2α, E2, D2 and 6-keto-F1α in human cerebrospinal fluid

Prostaglandin (PG)F_2α, E₂, D₂ and 6-keto-F_1α were determined in human cerebrospinal fluid by a mass spectrometric technique. The samples were obtained from 12 patients with suspected intracranial disease. A 64 fold variation in PG levels was observed. The major PG was 6-keto-F_1α (0.12–15 ng/ml). PGF_2α and PGE₂ were present in lower concentrations PGD₂ was below the level of detection (0.05 ng/ml) except in one patient with extremely high total levels of PGs.     

Urinary excretion of prostaglandin E2 and prostaglandin F2α in potassium-deficient rats

Potassium-deficiency was induced in rats by dietary deprivation of potassium. The animals became polyuric and urine osmolality decreased more then three-fold compared to controls. Urinary excretion of prostaglandin E₂ (PGE₂) and prostaglandin F_2α (PGF_2α) did not increase during 2 weeks of potassium depletion. Partial inhibition of renal prostaglandin synthesis by meclofenamate did not increase the urine osmolality after water deprivation. These results make unlikely the hypothesis that the polyuria of potassium-deficiency, is the result of enhanced renal synthesis of prostaglandins with subsequent antagonism of the hydro-osmotic effect of vasopressin. Male animals consistently excreted less PGE₂ than female animals.     

Effect of prostaglandins E1, E2 and F2α on neutrophil aggregation

Recently we have found that chemotactic factors stimulate neutrophils in suspension to aggregate. Because of an obvious analogy to platelet aggregation, we examined the influence of three prostaglandins on this process. Prostaglandins E₁, E₂ and F_2α alone did not cause aggregation of the neutrophils but were able to partially inhibit the aggregation response induced by the synthetic chemotactic tripeptide, formly-methionyl-leucyl-phenylalanine. The minimal inhibitory concentrations for prostaglandins E₁, E₂ and F_2α were 10⁻⁷, 10⁻⁶ and 10⁻⁵M, respectively. These results are similar to those found for the prostaglandin-induced inhibition of platelet aggregation. It may be, therefore, that neutrophil aggregation, like platelet aggregation, is modulated by intracellular prostaglandins and other products of arachidonic acid metabolism.     

Stereospecificity of enzymatic reduction of prostaglandin E2 to F2α

Antibodies directed toward PGF_2β were prepared in rabbits. The serologic specificity of the immune reaction was determined by inhibition of sodium borohydride-reduced (³H) PGE₂ anti-PGF_2β binding by several prostaglandins. The antibodies to PGF_2β recognize the β-hydroxyl configuration in the cyclopentane ring of PGF_2β. With the use of both anti-PGF_2α and anti-PGF_2β, the product of PGE₂ reduction by 9-ketoreductase purified from chicken heart was identified as PGF_2α. Guinea pig liver and kidney homogenates were examined for PGE 9-ketoreductase activity. Although enzyme activity was present, no evidence of PGF_2β production was found.     

The action of prostaglandin E2 and F1α on myocardial ischaemia-infarction arrhythmias in the dog

Prostaglandin E₂ and F_1α infusions have been tested for their ability to reduce the arrhythmias associated with occlusion of the left descending coronary artery in the anaesthetised dog. At 1 μg/kg/min both PGs reduced the incidence of premature ventricular contractions occurring during 25-min occlusions, while not reducing the incidence of ventricular fibrillation occurring on occlusion release. When infused for 5-min periods at 1 to 16 μg/kg/min, neither PGE₂ nor PGF_1α effectively reduced the frequency of ventricular arrhythmias occurring 24 hr after a permanent coronary occlusion.     

Differential effects of detergents and dimethylsulfoxide on membrane prostaglandin E1 and F2α receptors

Pretreatment of membranes for 1 hr at 4° with up to 0.1% Triton X-100 (TX-100) and sodium desoxycholate (SDC), resulted in a greater loss of [³H] prostaglandin (PG)F₂α binding compared to E₁ binding. Lubrol WX (LWX) tended to cause a greater loss of [³H]PGF₂α than E₁ binding. However, the differential loss was not as marked as with TX-100 or SDC. Triton X-305 was relatively ineffective, but loss of [³H]PGE₁ binding was greater than for PGF₂α. Increasing concentrations of dimethylsulfoxide (DMSO) progressively inhibited PGF₂α binding without affecting PGE₁ binding. The detergent, but not DMSO, induced losses of membrane PG binding were due to solubilization of the receptors. Greater amounts of membrane protein and phospholipids were solubilized at detergent (TX-100 and SDC) concentrations that solubilized 100% of PGE₁ receptors compared to 100% solubilization of F₂α receptors. Neither the duration of preincubation nor the amount of membrane protein chosen were responsible for differential PGE₁ and F₂α receptor losses. These differential membrane PG receptor losses raise the possibility of differences in PGE₁ and F₂α receptors association with the membrane structure.     

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.     

Intracerebroventicular injection of prostaglandin E1 increases γ-aminobutyric acid level in the posterior hypothalamus

The level of γ-aminobutyric acid (GABA) in the posterior hypothalamus, the firing rate of the nerves innervating interscapular brown adipose tissue (IBAT), IBAT and colonic temperatures (T_IBAT and T_c) were monitored in urethane-anesthetized male Sprague–Dawley rats. These variables were measured before and after an intracerebroventricular injection of 500 ng prostaglandin E₁ (PGE₁). The same variables were monitored in other rats with saline injection. The results showed that PGE₁ caused an increase in GABA concentration, firing rate, T_IBAT, T_c. These findings suggest that GABA-ergic tone in the posterior hypothalamus is important in the control of the sympathetic and thermogenic changes induced by PGE₁.     

Effect of prostaglandin F2α on ovulation and fertilization in rabbit

The effect of prostaglandin F_2α on ovulation and fertilization was studied in rabbits. The number of ovulation was not affected by subcutaneous injection of PGF_2α but the recovery of ova was significantly decreased when PGF_2α was given either at 12 or 16 h after HCG injection and autopsied 24 h latter. The results suggest that exogenous PGF_2α accelerates ovum transport and expels the eggs prematurely from the female tract and does not impair ovulation or the fertilization processes when given to rabbit at 1 mg/kg B.W.     

Different responses to prostaglandin F2α and E2 in human extra- and intramyometrial arteries

Tubal segments of the ascending uterine arteries and of intramyometrial arteries were obtained from 18 women who underwent hysterectomy at various phases of the menstrual cycle. Ring preparations of the vessels were mounted in organ baths and isometric tension was recorded. In extramyometrial arteries (outer diameter 2–3 mm) prostaglandin (PG) F_2α most potently, but also PGE₂ caused concentration-related contractions. In contrast, the contractant effects of both PGs on intramyometrial arteries (outer diameter 0.5–0.6 mm) were negligible. Both extra- and intramyometrial vessels were relaxed to a moderate degree (10–25%) by low concentrations of PGF_2α and PGE₂. No significant differences between the responses to vasopressin and noradrenaline were found between the vessel preparations. Thus human uterine arteries seem to change their responses to PGF_2α and PGE₂ as they enter the myometrium and decrease in diameter, and the results raise doubt about the view that direct vasoconstrictor effects of these PGs contribute to the regulation of myometrial blood flow. Such effects of vasopressin and noradrenaline cannot be excluded.     

Interferon γ stimulates prostaglandin E2 production by mouse Kupffer cells

When mononuclear phagocytes, including Kupffer cells, are activated by various agents, they synthesize and release arachidonic acid metabolites, prostaglandins (PGs) and leukotrienes (LTs). In this study, we examined the effect of in vitro Kupffer cell activation with recombinant murine IFN gamma on PGE2 and LTB4 secretion. IFN gamma enhanced PGE2 secretion, and this effect of IFN gamma was stronger than that of IL-1 or TNF. Moreover, IFN gamma promoted LTB4 release especially in the absence of PGs. On the other hand, dexamethasone and indomethacin inhibited and, EGTA and TMB-8, which reduce intracellular Ca++ Levels, blocked IFN gamma induced PGE2 production, which suggested that the activation of phospholipase A2 and cyclooxygenase in Kupffer cells requires the elevation of intracellular Ca++ levels.     

Acute toxicity of prostaglandins E2,F2α and 15 (s) 15 methyl prostaglandin E2 methyl ester in the baboon

The cardiovascular, uterine stimulant and gastrointestinal effects of prostaglandins E₂, F_2α and 15 (S) 15 methyl PGE₂ methyl ester in the East African Baboon (P. Anubis) have been studied. In these three parameters the baboon responds both qualitatively and quantitatively in a similar manner to man. The lethal doses of the prostaglandins given by bolus intravenous injelctions have been determined and the human lethal doses estimated.     

Effects of prostaglandin E2 and F2α on the absorption and portal transport of sugar and on the local intestinal circulation

With the isolated jejunum loop technique investigations of prostaglandin E₂ and F_2α were made on canine intestinal absorption and transport of glucose and on the circulation of the intestinal loop. These compounds decreased glucose absorption; intra-arterial prostaglandin administration decreased the portal transport of glucose, but intraluminal administration caused an increase. PGE₂ enhanced the circulation of the intestinal loop; intra-arterial PGF_2α diminished this circulation, whereas on intraluminal PGF_2α had no significant effect.     

Triphasic effect of prostaglandins E1, E2 and F2α on the fluid transport of isolated gall-bladder of guinea-pigs

Prostaglandins (PGs) F_2α, E₁ and E₂ exerted a triphasic influence on the fluid transport of isolated guinea-pig gall-bladders, when applied to the serosal side. PGE₁ and PGE₂ produced these effects in lower concentrations than F_2α. Directly after PG addition to the serosal side a short stimulation of fluid transport to between 200 and 400% was observed. The stimulatory effect of PGs was most distinct in gall-bladders from female guinea-pigs, less pronounced in male and nearly absent in pregnant animals. Since PGs increased intraluminal hydrostatic pressure in gall-bladders by contraction of the smooth muscle, experiments were performed in which hydrostatic pressure was increased by different procedures. These included the addition of imidazole (10⁻² M), raising of K⁺ in the bathing solution and an increase in intraluminal pressure by addition of Ringer's solution into the lumen. All three procedures stimulated fluid reabsorption temporarily in the same way as PGs, hence increase of intraluminal pressure is thought to be the reason for the observed temporary stimulation of fluid transport. Direct evidence for this thesis was obtained when the gall-bladder was mounted as a flat sheet over a chamber; in this preparation no stimulation of fluid transport was obtained. The second phase of the PG influence was characterized by a concentration-related inhibition of fluid reabsorption followed by a significant but small reverse of fluid transport (secretion of fluid). When PGs were applied to the mucosal side, only an inhibition of fluid transport was observed, which was much weaker compared to the addition to the serosal side.     

Effects of intracerebroventricular administration of PGE1, E2 and F2α on electrically induced convulsions in mice

Intracerebroventricular administration of prostaglandins E₁ or E₂ was shown to block, while PGF_2α increased the incidence of tonic convulsion due to electroshock in mice. The Prostaglandins were administered intracerebroventricularly (i.c.v.) to conscious mice by a modification of Haley and McCormick's method (1) prior to a transcorneal maximal electroshock (MES) or a transcorneal supra-maximal electroshock (SMES). PGE₁ and PGE₂ i.c.v. blocked the tonic hindlimb extension (THE) and protected the animals from death induced by MES with ED₅₀'s for PGE₁ and PGE₂ for inhibition of the THE of 6.6 (4.3–12.0) μg/mouse i.c.v. and 13.3 (8.9–22.4) μg/mouse i.c.v. respectively. When PGE₂ was administered intraperitoneally (i.p.) in doses as high as 4.0 mg/kg it did not block the THE. However, the duration of the THE as well as the mortality were reduced by doses of 0.5–4.0 mg/kg PGE₂ i.p.. Both PGE₁ and PGE₂ were shown to cause a dose related significant (p<.001) decrease in the duration of the THE with SMES in doses of 1–10 μg/mouse i.c.v. for PGE₁ and 2–40 μg/mouse i.c.v. for PGE₂. PGF_2α, administered i.c.v. prior to a transcorneal electroshock equivalent to a current at the ED₁ level, increased the incidence of the THE as well as the mortality in doses of 20–50 μg/mouse.     

Effects of prostaglandin E1 on contractility and Ca release in rabbit aortic smooth muscle

Concentrations of prostaglandin E₁ (PGE₁; 10⁻⁷ M) that do not elicit tension responses in aortic strips potentiate contractions induced by submaximal concentrations (10⁻⁸ − 10⁻⁷ M) of norepinephrine (NE) or angiotensin III (Ang III) but not those of high K⁺ depolarization or maximal NE or Ang III concentrations. Higher concentrations of PGE₁ (10⁻⁶ M and above) initiate contractions which are additive with submaximal responses to NE and Ang III but not to K⁺. These same concentrations of PGE₁ also decrease ⁴⁵Ca retention at high affinity La⁺⁺⁺-resistant sites in a manner similar to but not additive with NE and Ang III. Uptake of ⁴⁵Ca at low affinity La⁺⁺⁺-resistant sites (which is increased by high K⁺-depolarization) is not altered by 10⁻⁶ M PGE₁. The effects of PGE₁ are not altered by decreased extracellular Ca⁺⁺ (0.1 mM), decreased temperature, phentolamine or meclofenamate. Thus, PGE₁ does not appear to increase uptake of extracellular Ca⁺⁺ in this smooth muscle tissue. Instead, PGE₁ increases mobilization of Ca⁺⁺ from the same high affinity La⁺⁺⁺-resistant sites affected by Ang III and NE and, in this manner, may increase responses to these two stimulatory agents.     

Relation between prostaglandin E2, F2α, and cyclic nucleotides levels in rat brain and induction of convilsions

Fully convulsant doses of pentamethylenetetrazole cause marked increase in rat brain cortical PGF_2α, PGE₂, cGMP and cAMP during seizures, whereas subconvulsant doses cause an increase of rat brain cortical PGF_2α without affecting the other biochemical parameters considered. Rat cerebellar prostaglandins were not modified by the convulsant agent at either dosage.     

Effects of indomethacin and prostaglandin F2α on parturition in the hamster

In the female hamster, temporary sterility for a period of 10 or 15 days was induced by an intraperitoneal Silastic-PVP-tube containing 0.5 or 1.0 mg of PGF_2α, respectively. All Silastic-PVP-PGF_2α tube bearing animals regained fertility and delivered normal litters at various times after the placement of the tube. The release rate of ³H-PGF_2α from the Silastic-PVP tube was described and their potential use as a drug delivery system discussed.