Effect of acetaminophen on prostaglandin E2 and prostaglandin F2α synthesis in the renal inner medulla of rat

Effects of acetaminophen on the renal inner medullary production of prostaglandin E₂ and F_2α were compared with the well-known effects of aspirin on this process. Acetaminophen was found to elicit a dose-dependent inhibition of both prostaglandin E₂ and F_2α accumulation in media with a K_i of 100–200 μM. This inhibition could not be accounted for by increased accumulation of prostaglandins within slices. Acetaminophen inhibition was reversed by removal of acetaminophen during the incubation or by addition of arachidonic acid. Similar manipulations did not reverse aspirin or indomethacin-mediated inhibition of prostaglandin synthesis. Thin-layer and gas chromatographic analysis of acetaminophen following incubation with slices demonstrated that this material was identical to authentic acetaminophen. This, in addition to the lack of an effect of glutathione on inhibition, suggests that acetaminophen does not have to be metabolized to exert this inhibition. Arachidonic acid did not alter the metabolism or increase the efflux of acetaminophen. Lower levels of prostaglandin E₂ observed with 5 mM acetaminophen and 1 mM aspirin caused a corresponding decrease in cyclic AMP content. Removal of acetaminophen from the second incubation or addition of arachidonic acid caused increases in both prostaglandin E₂ and cyclic AMP. Aspirin inhibition of cyclic AMP content was not reversed by similar manipulations. In vivo inhibition of inner medullary prostaglandin E₂ and prostaglandin F_2α synthesis was observed 2 h after a 375 mg/kg, intraperitoneal injection of acetaminophen. These data suggest that acetaminophen, like aspirin, is capable of reducing tissue prostaglandin synthesis. However, the mechanisms by which these two analgesic and antipyretic agents elicit their inhibition of prostaglandin synthesis are quite different.     

Failure of prostaglandin F2α to affect LH secretion in the ovariectomized ewe

Prostaglandin F_2α (PGF_2α) when administered to ovariectomized ewes by intra-carotid infusion did not alter either the pattern of tonic LH secretion or the LH surge evoked by estradiol, indicating that, in the sheep, the luteolytic action of PGF_2α does not involve alteration of LH secretion by the pituitary gland.     

Failure of prostaglandin F2α to affect LH secretion in the ovariectomized ewe

Prostaglandin F_2α (PGF_2α) when administered to ovariectomized ewes by intra-carotid infusion did not alter either the pattern of tonic LH secretion or the LH surge evoked by estradiol, indicating that, in the sheep, the luteolytic action of PGF_2α does not involve alteration of LH secretion by the pituitary gland.     

Rapid accumulation of polymorphonuclear neutrophils in the Corpus luteum during prostaglandin F(2α)-induced luteolysis in the cow

Prostaglandin F(2α) (PGF(2α)) induces luteolysis within a few days in cows, and immune cells increase in number in the regressing corpus luteum (CL), implying that luteolysis is an inflammatory-like immune response. We investigated the rapid change in polymorphonuclear neutrophil (PMN) numbers in response to PGF(2α) administration as the first cells recruited to inflammatory sites, together with mRNA of interleukin-8 (IL-8: neutrophil chemoattractant) and P-selectin (leukocyte adhesion molecule) in the bovine CL. CLs were collected by ovariectomy at various times after PGF(2α) injection. The number of PMNs was increased at 5 min after PGF(2α) administration, whereas IL-8 and P-selectin mRNA increased at 30 min and 2 h, respectively. PGF(2α) directly stimulated P-selectin protein expression at 5-30 min in luteal endothelial cells (LECs). Moreover, PGF(2α) enhanced PMN adhesion to LECs, and this enhancement by PGF(2α) was inhibited by anti-P-selectin antibody, suggesting that P-selectin expression by PGF(2α) is crucial in PMN migration. In conclusion, PGF(2α) rapidly induces the accumulation of PMNs into the bovine CL at 5 min and enhances PMN adhesion via P-selectin expression in LECs. It is suggested that luteolytic cascade by PGF(2α) may involve an acute inflammatory-like response due to rapidly infiltrated PMNs.     

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.     

Investigations on the detrimental effect of prostaglandin F2α-regulated estrus on the number and condition of sperm in the reproductive tract of the ewe

Ewes in the luteal phase of the estrous cycle were treated with prostaglandin F₂α (PGF), mated to rams at the ensuing estrus 2 days later, and necropsied at 2 or 23 hr after mating. At 2 hr after mating, ewes in PGF-regulated estrus had significantly fewer sperm in the middle and anterior one-thirds of the cervix and in the uterus than did ewes mated during natural estrus. At 23 hr, soon after ovulation, significantly fewer ewes in PGF-regulated estrus had sperm in the oviducts than did ewes in natural estrus.In Experiment 2, ewes in PGF-regulated or natural estrus were laparotomized, inseminated by deposition of semen in the uterine lumen, and necropsied 2 or 23 hr later. Intrauterine insemination prevented most of the reduction in sperm numbers in the reproductive tract at PGF-regulated estrus.In Experiment 3, ewes in PGF-regulated or natural estrus were either mated to rams or inseminated in the uterine lumen and necropsied 2 hr later. Sperm were recovered from three segments of the cervix and were counted and evaluated for motility, response to live-dead staining, and acrosomal morphology. Intrauterine insemination again reduced the detrimental effect of PGF-regulated estrus on sperm numbers. However, the percentages of sperm recovered from the cervix that were motile, live, and had normal acrosomes were much lower in ewes in PGF-regulated estrus than in ewes in natural estrus. Compared with natural mating, intrauterine insemination reduced but did not eliminate the detrimental effects of PGF-regulated estrus on the viability and morphology of sperm. Regulating estrus with PGF resulted in damage to sperm in the cervix regardless of whether sperm reached the cervix from the vagina or from the uterus.     

Effects of repeated daily injections of prostaglandin F2α on ovaries in mares

In experiment 1, seven groups of pony mares (2 or 3/group) were given either no injections (controls), or 5(5X) or 10(10X) daily subcutaneous (SC) injections of 1.25 mg PGF_2α beginning on days 1, 7 or 13 post-ovulation. Compared to controls (24.5 days), the interovulatory interval was longer (P<.05) for day 7, 10X (33.5 days) and day 13, 10X mares (49.0 days) but was not different for the remaining groups. In experiment 2, nine groups of pony mares (4/group) were given either no injections (controls) or 1(1X) or 10(10X) daily SC injections of 1.25 mg PGF_2α beginning on day 2 of estrus or on days 1, 7 or 13 post-ovulation. Compared to controls (25.0 days), the interovulatory interval was longer (P<.05) for day 13 post-ovulation, 10X mares (40.0 days) and shorter (P<.05) for day 1 post-ovulation, 10X mares (14.5 days). The interovulatory interval for the remaining groups was not different (P>.05) from that for controls. In day 13 post-ovulation, 10X mares, the longer interovulatory interval did not appear to be related to a depression in either peripheral LH concentration (no effect of treatment on LH) or on follicular development (no effect of treatment on diameter of largest follicle). This suggests that circulating levels of gonadotropins were adequate for ovarian follicular development and ovulation and the effect of repeated daily injections of PGF_2α in preventing ovulation was likely exerted at the ovarian level directly on the follicle.     

Determination of prostaglandin F2α and E2 contents in human cerebrospinal fluid by the radioisotope dilution method

Prostaglandin F_2α and E₂ contents in human cerebrospinal fluid were determined by the radioisotope dilution method. The mean values of PGF_2α and PGE₂ of men were 9.8±0.87 ng/ml and 6.5±1.39 ng/ml, respectively. Those of women were 8.3±1.4 ng/ml and 6.9±1.72 ng/ml, respectively. The correlation between age and PG was significantly with PGE₂ of men and with PGF_2α of women.     

Pharmacotherapeutics of prostaglandin E2 and 15 (S) 15-methyl prostaglandin F2α in chronic schistosomal bladder ulcer: A clinico-endoscopic study

The pharmacotherapeutic effects of prostaglandin E₂ (PGE₂) and 15 (S) 15-methyl PGF_2α given by different routes of administration, were studied in 20 normal persons and 100 patients with chronic schistosomal bladder ulcer in comparison to normal saline and antimony dimercaptosuccinate drug. Prostaglandins produced a rapid significant amelioration in the ulcer symptom complex with a good percentage of ulcer disappearance on cystoscopy, while the antimony dimercaptosuccinate treated group showed a less early response which improved with follow up. This was in contrast to prostaglandins which showed relapse in the symptom-complex in some cases after a follow up period of 2 months. The combined use of schistosomicidal drugs together with, or followed by, prostaglandins might give better results.     

Bronchodilating properties of the prostaglandin F2β in the guinea pig and cat

The bronchodilating properties of PGF_2β (a stereo-isomer of the naturally occurring bronchoconstrictor (PGF_2α) are described in the guinea pig and cat. The possible physiologic implications of this finding are discussed.     

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.     

Central cardiovascular activity of prostaglandin E2, prostagladin F2∝ and prostacyclin

Prostacyclin (PGI₂), prostaglandin E₂ (PGE₂) and prostaglandin F_2∝ (PGF_2∝) were tested here in unanesthetized male Sprague-Dawley rats for their effects on the cardiovascular system as mediated by the Central nervous system. Cannulae were chronically implanted into the third cerebral ventricle, femoral arteries and femoral veins of rats. Both PGE₂ and PGF_2∝ induced increased arterial blood pressure and tachycardia by an action on the central nervous system. The changes seen with PGE₂ were larger than those observed with PGF_2∝. Only transient depressor effects were seen with PGI₂ and these changes appeared to be due to the leakage of the substance into the peripheral vascular system.     

Inhibitory effects of aspirin and indomethacin on the biosynthesis of PGE2 and PGF2α

A gas-liquid chromatography system has been used to study the effects of indomethacin and aspirin on the biosynthesis of PGE₂ and PGF_2α by the prostaglandin synthetase system of bovine seminal vesicle. Both compounds were found to inhibit the production of PGE₂ and PGF_2α. However, based on statistical analyses, the inhibitory effect of indomethacin was found to be non-selective while aspirin produced statistically significant preferential inhibition of PGE₂ over PGF_2α.     

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.     

Effects of prostaglandins E2 and F2α on lecithin biosynthesis by cultured lung cells

Transformed cells from human lung carcinoma (Line A549), resembling type II pneumocytes, were cultured in monolayer at 37°C and incubated for five hours with ³H-choline and ¹⁴C-palmitate in the presence of various concentrations of prostaglandins (PGs) E₂ and F_2α. In the control (no PG) the level of % palmitate incorporation was 13.5 × as high as that of choline, after taking isotope dilution into account. Between the concentrations studied, 0.1 and 10 μM, both prostaglandins stimulated markedly the incorporation of both precursors, though choline up to 3 × better than palmitate. This was indicated by a change in the palmitate/choline incorporation ratio from 13.5 to as low as 4.2. At the lowest PG concentration, 0.1 μM, PGE₂ was much more effective than PGF_2α in stimulating the incorporation of both precursors.     

Effects of inhibition of prostaglandin F2α biosynthesis during preluteolysis and luteolysis in heifers

Flunixin meglumine (FM; 2.5 mg/kg) was given to heifers at three 8-h intervals, 16 d after ovulation (first treatment = Hour 0) to inhibit the synthesis of prostaglandin F_2α (PGF), based on plasma concentrations of a PGF metabolite (PGFM). Blood samples were collected at 8-h intervals from 15 to 18 d in a vehicle (control) and FM group (n = 16/group). Hourly samples were collected from Hours −2 to 28 in 10 heifers in each group. Heifers that were in preluteolysis or luteolysis at Hour 0 based on plasma progesterone (P4) concentrations at 8-h intervals were partitioned into subgroups. Concentration of PGFM was reduced (P < 0.05) by FM treatment in each subgroup. For the preluteolytic subgroup, the first decrease (P < 0.05) in P4 concentration after Hour 0 occurred at Hours 24 and 40 in the vehicle and FM groups, respectively. Plasma P4 concentrations 32 and 40 h after the beginning of luteolysis in the luteolytic subgroup were greater (P < 0.05) in the FM group. Concentration at the peak of a PGFM pulse in the FM group was greater (P < 0.05) in the luteolytic than in the preluteolytic subgroup. The peak of a PGFM pulse occurred more frequently (P < 0.001) at the same hour as the peak of an LH fluctuation than at the ending nadir of an LH fluctuation. In conclusion, a reduction in prominence of PGFM pulses during luteolysis delayed completion of luteolysis, and treatment with FM inhibited PGFM production more during preluteolysis than during luteolysis.     

Synthesis of 11β-3H-prostaglandin E2

11β-³H-Prostaglandin E₂ was synthesized by the stereoselective reduction of the PGD₂ derivative $\text{2}$ using sodium borotritide.     

Effect of exogenous estradiol and progesterone on the uterine tissue levels of prostaglandin F2α (PGF2α) in ovariectomized mice

Mice ovariectomized for 14 days were treated for 6 days with estradiol and/or progesterone. Both the steroids were effective in increasing the levels of PGF_2α in the uterine tissue, but the treatment with progesterone for 3 days followed by 3 days of estrogen resulted in a highly significant production of PGF_2α. It is concluded that for the production of PGF_2α both estrogen and progesterone are necessary and that the pretreatment with progesterone followed by estrogen results in the maximum production of PGF_2α.