Comparison of the effects of prostaglandins D2, F2α and E1 on spontaneous contractions of rabbit oviduct

The effects of PGD₂, PGF_2α and PGE₁ were studied on the circular muscle of post-ovulatory rabbit oviducts $\text{in vitro}$. PGE₁ inhibited spontaneous contractile activity. Lower concentrations of PGD₂ and PGF_2α were stimulatory and higher concentrations were inhibitory. Since PGD₂ may be produced in the oviduct, any hypothesis concerning the role of prostaglandins in the control of oviductal motility and ovum transport should include PGD₂ as well as PGFs and PGEs.     

The effect of prostaglandins A2,E1,E2,15 methyl E2, 16, 16 dimethyl E2 and F2α on erythropoiesis

Prostaglandins A₂, E₁, E₂, methylated E₂s and F₂α affected erythropoiesis and/or erythropoietin (Ep) production. This action is indicated in the exhypoxic, polycythemic mouse where radioiron incorporations into RBC increased after administration of these compounds. The kidney and liver have been indicated through previous studies, to actively participate in Ep production. By the removal of one of these active sites in a murine system treated with prostaglandins it is shown that a response is reflected in Ep levels. Interference of the action of prostaglandins (PG) is altered by the removal of one of these target sites of Ep production. The erythropoietic responses elicited by PGA₂, E₁, and perhaps the methylated PGE₂s act through the liver whereas PGE₂ may operate through a renal pathway for its response. PGF_2α reveals no effect on erythropoietic activity and is no different than that observed for vehicle-treated controls. The prostaglandins tested appear to act primarily through the kidney or liver but the possibility exists that some yet undetermined organ site may also be involved.     

The effects of prostaglandins E2 and F2α on synaptosomal accumulation and release of 3H-norepinephrine

Prostaglandins (PG) of both the E and F series may serve as modulators of norepinephrine (NE) release from peripheral sympathetic neurons. We have studied the effects of PGE₂ and PGF_2α on the accumulation and release of ³H-NE in the CNS using synaptosomes isolated from rat hypothalami.The release of ³H-NE from synaptosomes superfused with Krebs-Ringer bicarbonate buffer was multiphasic with an initial fast release phase followed by a slower release. Raising KC1 concentration of the superfusion medium to 56mM during the slow release phase is known to stimulate ³H-NE release. PGE₂ (1 × 10^?6M) attenuated ³H-NE release during the fast phase and reduced the amount of ³H-NE released due to KC1 stimulation. At lower concentrations of PGE₂ there was no change in the release profile. PGF_2α was without effect on ³H-NE release at all concentrations tested.The accumulation of ³H-NE was significantly diminished by PGE₂ at a concentration of 1 × 10^?6M, while a lower concentration (1 × 10^?7M) was ineffective. PGF_2α had no effect on ³H-NE accumulation at all concentrations investigated.     

Radioimmunoassay for urinary metabolites of prostaglandin F2α

Antibodies against the main urinary metabolite of PGF_2α in the human, 5α,7α-dihydroxy-11-ketotetranorprosta-1,16-dioic acid, were raised in rabbits. The compound was coupled selectively in the ω position to bovine serum albumin prior to injection. The resulting antibodies did not distinguish between tetranor compounds varying only in structure at the ω carbon, and thus the assay could be used also for other metabolites of PGF_2α, e.g. the main urinary metabolite in the guinea pig, 5α,7α-dihydroxy-11-ketotetranorprostanoic acid. Labeled ligands for the assays were prepared either $\text{in vivo}$ by injection of |17,18-³H|-PGF_2α into humans after several days' treatment with indomethacin, or $\text{in vitro}$ by incubation of |17,18-³H|-15-keto-13,14-dihydro-PGF_2α with mitochondria from rat liver. The sensitivity of the assay was 10 pg or 4 pg with these two preparations, respectively.The assay was employed for a number of measurements: normal daily excretion in a number of humans; excretion of urinary metabolites during treatment with prostaglandin synthetase inhibitors in human subjects, or after intravenous injection of PGF_2α; excretion during human pregnancy; and prostaglandin production in the guinea pig during normal estrous cycles and pregnancies and after estrogen treatment.The results of these studies were in several cases compared to similar measurements earlier performed using mass spectrometric methods, and were found to agree well. Thus, this radioimmunoassay provides a simple and accurate method for estimating prostaglandin production, particularly suitable for long-term studies and for cases where repeated blood sampling must be avoided.     

Measurement of prostaglandin F2α metabolites by radioimmunoassay

Antibodies against 15 keto PGF_2α and 13,14 dihydro 15 keto PGF_2α were produced in goats and rabbits using the appropriate prostaglandin protein conjugate. Tritium labeled 15-keto, and 13,14 dihydro 15-keto PGF_2α were prepared from ³H-PGF_2α. These antibodies and ³H-labeled compounds were used to develop radioimmunoassays for the respective F_2α metabolites. The antibodies had relatively little cross-reactivity (≤0.1%) with the parent F_2α molecule. Infusion of PGF_2α in monkeys increased 15-keto-h₂ levels 10–20 fold higher than PGF_2α in peripheral plasma. The levels of this metabolite were not altered detectably during clotting, indicating relatively slow rates of PGF_2α metabolism in vitro. These assays should be useful to follow release rates of exogenous prostaglandins from various formulations and delivery systems, and in vivo tissue synthesis of PGF_2α, where low levels preclude measuring the parent compound.     

Synthesis of prostaglandin E2 and prostaglandin F2α by toadfish red blood cells

Saline washed red blood cells of the toadfish convert [1-¹⁴C] arachidonic acid to products that cochromatograph with prostaglandin E₂ and prostaglandin F_2α. This synthesis is inhibited by indomethacin (10 μg/ml). Conversion of arachidonic acid to prostaglandin E₂ was confirmed by mass spectrometry. When saline washed toadfish red blood cells were incubated with a mixture of [1-¹⁴C]-arachidonic acid and [5,6,8,9,11,12,14,15,-³H]-arachidonic acid, comparison of the isotope ratios of the radioactive products indicated that prostaglandin F_2α was produced by reduction of prostaglandin E₂. The capacity of toadfish red blood cells to reduce prostaglandin E₂ to prostaglandin F_2α was confirmed by incubation of the cells with [1-¹⁴C] prostaglandin E₂.     

A study of prostaglandin F2α as the luteolysin in swine: I. Effect of prostaglandin F2α in hysterectomized gilts

Experiments were conducted to determine if prostaglandin F_2α (PGF_2α) is luteolytic in swine. In Experiment 1, four bilaterally hysterectomized gilts were injected with PGF_2α at 0800 (10mg) and 2000 hours (10mg) and four gilts received .9% saline at the same times on day 17 after onset of estrus. Treatments were reversed in the two groups of gilts 21 days later. All eight PGF_2α treated gilts exhibited estrus an average of 88.0 ± 13.5 hours after treatment and average duration of estrus was 66.0 ± 16.4 hours. Saline treated controls did not exhibit estrus. Two additional gilts were hysterectomized bilaterally and the saphenous artery catheterized on day 7 after onset of estrus. PGF_2α injected on day 17 resulted in a precipitous decline in plasma progestin concentration and onset of estrus by 110 and 90 hours in gilts 1 and 2, respectively. Another bilaterally hysterectomized gilt, with CL marked with India ink, received PGF_2α on day 17. Estrus occurred 92 hours later and, on day 4, regression of marked CL to corpora albicantia and presence of newly formed CL was confirmed at laparotomy.In Experiment 2, 12 bilaterally hysterectomized gilts were treated with PGF_2α at 0800 (10mg) and 2000 hours (10mg) on either day 8, 11, 14 or 17 after onset of estrus. None of the gilts treated on days 8 and 11 exhibited estrus. Two of three gilts treated on day 14 and all three gilts treated on day 17 exhibited estrus at an average of 116.0 ± 9.8 hours post-treatment. Average duration of estrus was 49.6 ± 8.8 hours.     

Influence of prostaglandins (PG) E2 and F2α on the inflammatory process

PGF_2^α, but not PGE₂, induces a slight pedal edema when given alone. Both compounds were equipotent in the carrageenin-induced rat paw edema. Locally administered, PGE₂ and PGF_2^α did not exacerbate, but rather inhibited inflammations induced by various agents such as 1% carrageenin or 1% egg white. The administration of PGE₂ directly into cotton pellets or into the rat's hind paw in combination with M. butyricum significantly inhibited, respectively, granuloma formation and the polyarthritis. Subcutaneously, both prostaglandins inhibited the adjuvant induced polyarthritis. Neither PGE₂ nor PGF_2^α inhibited the anti-edema properties of non-steroidal or steroidal anti-inflammatory standards. A greater anti-edema activity was observed with the combination treatment than with the anti-inflammatory standards alone. We were unable to decrease the anti-inflammatory activity of the steroidal and non-steroidal standards or increase the inflammatory potential of the phlogistic agents.     

Radioimmunoassays of prostaglandin F2α and prostaglandin F2α-main urinary metabolite with prostaglandin-125I-tyrosine methylester amide

Radioimmunoassays for measuring prostaglandin F_2α (PGF_2α) and 5α, 7α-dihydroxy-11-keto tetranorprosta-1,16-dioic acid, PGF_2α-main urinary metabolite (PGF_2α-MUM), with ¹²⁵I-tyrosine methylester amide (TMA) of PGF_2α and PGF_2α-MUM were developed.Antibody to PGF_2α was produced in rabbits immunized with conjugates of PGF_2α coupled to bovine serum albumine. Antibody to PGF_2α-MUM was also produced in rabbits immunized with conjugates of PGF_2α-MUM coupled to bovine serum albumin.PGF_2α-¹²⁵I-TMA had an affinity to antiserum to PGF_2α. PGF_2α-MUM-¹²⁵I-TMA also responded to antiserum to PGF_2α-MUM.     

Aminoterminal acetylation of synthetic Nα-desacetyl thymosin α1

A transacetylase associated with the ribosome fraction from wheat germ catalyzes the transfer of acetyl groups from acetyl CoA to synthetic N^α-desacetyl thymosin α₁. The product was identified by high-performance liquid chromatography and by the isolation of a tryptic peptide containing the acetylated NH₂-terminus. In 20 min, with 13 μg of enzyme protein, 15% of the desacetyl thymosin α₁ added was converted to the acetylated form. Under the conditions employed only the α-NH₂ group was acetylated.     

Omega chain methylated analogs of PGF2α and PGE2

Our previously published prostaglandin (PG) synthesis route, in which the ω-chain is added in the penultimate step, provides facile access to a wide variety of ω-chain variant PG analogs. Each series requires only the synthesis of the appropriate methylated acylphosphonate for the Emmons' condensation. The syntheses of analogs bearing the following methylation pattern are detailed: 15-Me; 17, 17-(Me)₂; 17, 17, 20-(Me)₃; 18, 18, 20-(Me)₃; 15, 18, 18, 20-(Me)₄; and 15-Ome-18, 18, 20-(Me)₃. The well-known 16, 16-dimethyl prostaglandins have also been prepared by this sequence. The synthesis of 16, 16-tetramethylene-PG analogs is also described.     

Effect of PGD2, PGE2, PGF2α and PGI2 on blood pressure,heart rate and plasma catecholamine responses to spinal cord stimulation in the rat

The following experiments were designed in order to examine the inter-relationships of various prostaglandins (PG's) and the adrenergic nervous system, in conjunction with blood pressure and heart rate responses, $\text{in vivo}$. Stimulation of the entire spinal cord (50v, 0.3–3 Hz, 1.0 msec) of the pithed rat increased blood pressure, heart rate and plasma epinephrine (EPI) and norepinephrine (NE) concentration (radioenzymatic-thin layer chromatographic assay). Infusion of PGE₂(10–30 μg/kg. min, i.v.) suppressed blood pressure and heart rate responses to spinal cord stimulation while plasma EPI (but not NE) was augmented over levels found in control animals. PGI₂ (0.03–3.0 μg/kg. min, i.v.) suppressed the blood pressure response to spinal cord stimulation without any effect on heart rate or the plasma catecholamine levels. PGE₂ and PGF_2α(10–30 μg/kg. min, i.v.) did not change the blood pressure, heart rate or plasma EPI and NE responses to the spinal cord stimulation although PGF_2α disclosed an overall vasopressor effect during the pre-stimulation period. At the pre-stimulation period it was also observed that PGE₂, PGF_2α and PGI₂, had a positive chronotropic effect on the heart rate, the cardiac accelerating effect of PGE₂ was not abolished by propanolol. These $\text{in vivo}$ studies suggest that in the rat, PGE₂ and PGI₂ modulate sympathetic responses, primarily by interaction with the post-synaptic elements — PGE₂ on both blood vessels and the heart and PGI₂ by acting principally on blood vessels.     

Sexual behavior of castrated boars treated with prostaglandin F2α

The objectives were to test the hypothesis that exogenous prostaglandin F_2α (PGF_2α) temporarily restores sexual behavior of castrated boars, and to evaluate effects of PGF_2α on serum hormone concentrations. At 35 d after castration, nine lean-type adult boars were randomly assigned to three treatments in a 3 × 3 latin square (with three replicates). Treatments were three doses of PGF_2α doses (0, 10, and 20 mg) and three periods of treatment, with 5 d between each period. Serum testosterone (T) concentrations were non-detectable at the start of the experiment. Serum concentrations of estradiol (E2), LH, prolactin (PRL), and cortisol were unaffected (P > 0.05) by PGF_2α treatment. The interval from treatment to ejaculation in boars treated with 10 mg (758 s) or 20 mg (660 s) PGF_2α did not differ, but were different (P < 0.05) from control boars (>1 800 s). Ejaculation duration and false mounts differed (P < 0.05) between control boars and boars treated with 10 or 20 mg PGF_2α. In conclusion, PGF_2α treatment did not change serum concentrations of T, E2, LH, PRL, or cortisol, but restored sexual behavior. This restoration may have been due to an effect of PGF_2α directly in specific areas of the brain, or indirectly via release of other hormones that stimulated areas in the brain that affected sexual behavior.     

Termination of early gestation with vaginal prostaglandin F2α tablets

The abortifacient activity of prostaglandin F_2α was investigated by placing one or two 50 mg tablets of prostaglandin F_2α in THAM salt into the vagina of nine women less than 4 weeks pregnant at intervals of 2 to 4 hours for a 24 hour period. Serum levels of HCG, estradiol (E₂), progesterone and 17α-hydroxyprogesterone were measured by radioimmunoassay prior to starting therapy and at frequent intervals thereafter for 48 hours. All but two patients had significant side-effects, mainly diarrhea and vomiting, indicating that systemic absorption took place. Although bleeding was induced in 8 of 9 women, only 3 had complete abortions. A D&C was performed on all patients 48 hours after starting therapy. A significant fall in HCG levels was noted only in the patients who aborted. Only 3 of the 9 women had significant changes in steroid levels. A fall in progesterone and 17α-hydroxyprogesterone occurred in the 3 women who aborted and took place following the fall in HCG. Estradiol levels remained in the same range in all subjects. These findings indicate that prostaglandin F_2α when administered in this vehicle and this dosage is relatively ineffective as an abortifacient. When effective, its action would appear to be due to contractions of uterine muscle and not secondarily to luteolysis.     

Letter to the editor Synthesis of 16-fluoromethylene-prostaglandin F2α

Prostaglandin (PG) E₂, thromboxane (TX) B₂ and the stable breakdown product of prostacyclin, 6-oxo-PGF_1α are present in carrageenin-induced inflammatory exudates. Carrageenin-impregnated polyester sponges were implanted subcutaneously in rats and inflammatory exudates were collected 4–192 h after implantation. The concentrations of cyclo-oxygenase products in sponge fluids was measured by radioimmunoassay after extraction and purification. All three products were detectable after 4 h and reached a peak at 12–24 h. Mean TXB₂ concentrations reached 74 ng/ml at 12 h but decreased to less than 10 ng/ml after 24 h. PGE₂ concentrations were 65 ng/ml at 24 h, after which there was no significant increase and then dropped to about 20 ng/ml between 96 and 192 h. 6-oxo-PGF_1α reached a concentration of 33 ng/ml at 24 h which did not change significantly until levels fell to less than 10 ng/ml between 96 and 192 h. The presence of PGE₂, TXB₂ and 6-oxo-PGF_1α was confirmed by gas-liquid chromatography and mass spectrometry. Total leukocyte numbers increased steadily and were at their highest (116.0 × 10⁶ cells/ml) at 192 h. These results suggest that thromboxanes and prostacyclin, as well as PGE₂, contribute to the acute inflammatory response.     

The roles of PGF2α and PGE2 in regression of the corpus luteum after intrauterine infusion of Arcanobacterium pyogenes in cows

To study the effect of bacteria in the uterus on the fate of the corpus luteum (CL), Arcanobacterium pyogenes was inoculated into the uteri of cows on Day 3 (Day 0 = day of spontaneous ovulation). Plasma concentrations of 13,14-dihydro-15-keto-PGF_2α (PGFM), 13,14-dihydro-15-keto-PGE₂ (PGEM) and progesterone (P₄) were determined. In five cows, the developing CL regressed and first-wave dominant follicles, which normally become atretic, ovulated (Group OV) after bacterial inoculation. In another five cows (Group NOV) and five control cows, the developing CL did not regress and first-wave dominant follicles did not ovulate. In Group OV, PGFM concentrations increased by 126.2 pg/mL (from 36.8 ± 7.8 pg/mL on Day 3 to 163 ± 37.2 pg/mL on Day 6), with an increase ratio of 5.8-fold. Conversely, in Group NOV, PGFM had a greater increase of 198.4 pg/mL (from 128.2 ± 27.8 pg/mL on Day 3 to 326.6 ± 115.1 pg/mL on Day 5), but the increase ratio was only 2.3-fold. Although PGEM tended to increase in both groups, raw increases and increase ratios were small. Bacterial inoculation into the uterus stimulated the release of prostaglandins and affected the fate of the CL; in that regard, the CL was affected more by PGF_2α than by PGE₂, and the increase ratio of PGF_2α was more important than the raw increase.     

Mechanism of the inhibition of platelet aggregation produced by prostaglandin F2α

The inhibition of human platelet aggregation produced by PGF_2α is not specific for thromboxane A₂ mimetics. Aggregation waves induced by PAF and thrombin are also inhibited by PGF_2α (8 μM); ADP is unaffected. These effects are still seen in platelets from aspirin-treated donors and platelets desensitized to thromboxane-like agonists (e.g. 11,9-epoxymethano PGH₂). In contrast the thromboxane receptor antagonist EP 045 (up to 20 μM) had no effect on primary aggregation induced by PAF, thrombin and ADP. We have previously shown that EP 045 (IC₅₀ = 0.5 μM), displaces the specific binding of [³H] 9,11-epoxymethano PGH₂ to washed human platelets.PGF_2α produces small increases in cAMP levels, and both this effect and the anti-aggregation are diminished by the adenyl cyclase inhibitor SQ 22536. The rise in cAMP induced by PGF_2α is inhibited to a greater extent by the presence of ADP than by thrombin, PAF or a thromboxane mimetic. The ability of aggregating agents to inhibit this increase correlates inversely with their sensitivity to inhibition by PGF_2α.We suggest that the very weak effect of PGF_2α on cyclic AMP_ production is sufficient to account for its inhibitory activity, and it is unlikely to be a competitive antagonist at the platelet thromboxane receptor as suggested by others.     

Radioimmunoassay of main urinary metabolite of prostaglandin F2α in normal subjects

Radioimmunoassay of 5α,7α-dihydroxy-11-keto-tetranorprosta-1, 16-dioic acid, main urinary metabolite of prostaglandin F F_2α (PGE_2α-MUM), was performed in normal subjects. Twenty-four hours secretion of PGF_2α-MUM were 29.04 ± 9.73 μg in males and 18.22 ± 5.88 μg in females on an average. And an oral administration of aspirin resulted in the remarkable decrease of PGF_2α-MUM in both sexes.     

Molecular structure of tetranuclear [{Mo2O(S2CNEt2)(η-O2CCF3)(μ-N-o-tol)2}2(μ-O)(μ-O2CCF3)2] formed upon addition of trifluoroacetic acid to syn-[MoO(μ-N-o-tol)(S2CNEt2)]2

Addition of trifluoroacetic acid to syn-[MoO(μ-N-o-tol)(S₂CNEt₂)]₂ in chloroform affords tetranuclear [{Mo₂O(S₂CNEt₂)(η¹-O₂CCF₃)(μ-N-o-tol)₂}₂(μ-O)(μ-O₂CCF₃)₂] which has been crystallographically characterised. It consists of four molybdenum(V) centres linked via bridging imido, trifluoroacetate and oxo ligands and results from replacement of a dithiocarbamate by two trifluoroacetate ligands.