Increase In Prostaglandin E2 Concentration Research Articles

Dietary Long‐chain PUFAs Enrich Porcine Alveolar Macrophages and Alter Prostaglandin E2 Production Following LPS Challenge

The US swine industry experiences severe production and profit losses from respiratory infections despite the wide spread use of vaccines and antibiotics. Long‐chain PUFAs can modulate immune cell function through the production of eicosanoids, such as prostaglandin E2 (PGE2) which is capable of stimulating both inflammation and inflammatory resolution upon infection. The aim of this study was to determine the effects of dietary arachidonic acid (ARA) and eicosapentaenoic acid (EPA) on cultured porcine alveolar macrophages stimulated with LPS. Day‐old pigs (n=60) were fed milk replacer for 21d. Diets contained 0.5% ARA (control), 2.5% ARA or 3.5% EPA of total fatty acids. Alveolar macrophages were isolated via bronchoalveolar lavage, cultured and stimulated with LPS for 24h. Total fatty acids in alveolar macrophages and lung tissue were analyzed via gas chromatography‐mass spectrometry (GC‐MS). Alveolar macrophages were cultured and stimulated with 10ng/mL LPS or unstimulated (control). Concentrations of PGE2 in tissue culture media were measured via competitive enzyme‐linked immunosorbent assay (ELISA) kits. Average body weight and clinical hematology were unaffected by diet treatments (P >0.5). Concentration of ARA (% of fatty acids, w/w) in alveolar macrophages from pigs fed 2.5% ARA had an 82% increase in ARA compared to controls, and the concentration was decreased 21% in pigs fed 3.5% EPA compared to control (P < 0.01). Lung parenchymal tissue showed a similar enrichment pattern; tissue was enriched by 39% in pigs fed 2.5% ARA, while pigs fed the 3.5% EPA diet had a 45% decrease in ARA compared to control (P < 0.002). Media concentration of PGE2 was increased following LPS stimulation of alveolar macrophages. The increase in PGE2 concentration was greater in macrophages enriched in ARA, exceeding that from control cells by 187% and that from EPA‐enriched cells by 191% (P < 0.05). These data demonstrate that dietary supplementation of LC‐PUFAs can effectively alter lung tissue and alveolar macrophage fatty acid composition. Furthermore, these data validate that increased dietary ARA is an effective means to increase eicosanoid production by LPS‐stimulated immune cells.Support or Funding InformationUSDA Animal Health Funds

Dietary Linoleic Acid Lowering Reduces Lipopolysaccharide-Induced Increase in Brain Arachidonic Acid Metabolism.

Linoleic acid (LA, 18:2n-6) is a precursor to arachidonic acid (AA, 20:4n-6), which can be converted by brain lipoxygenase and cyclooxygenase (COX) enzymes into various lipid mediators involved in the regulation of brain immunity. Brain AA metabolism is activated in rodents by the bacterial endotoxin, lipopolysaccharide (LPS). This study tested the hypothesis that dietary LA lowering, which limits plasma supply of AA to the brain, reduces LPS-induced upregulation in brain AA metabolism. Male Fischer CDF344 rats fed an adequate LA (5.2% energy (en)) or low LA (0.4% en) diet for 15weeks were infused with LPS (250ng/h) or vehicle into the fourth ventricle for 2days using a mini-osmotic pump. The incorporation rate of intravenously infused unesterified 14C-AA into brain lipids, eicosanoids, and activities of phospholipase A2 and COX-1 and 2 enzymes were measured. Dietary LA lowering reduced the LPS-induced increase in prostaglandin E2 concentration and COX-2 activity (P < 0.05 by two-way ANOVA)without altering phospholipase activity. The 14C-AA incorporation rate into brain lipids was decreased by dietary LA lowering (P < 0.05 by two-way ANOVA). The present findings suggest that dietary LA lowering reduced LPS-induced increase in brain markers of AA metabolism. The clinical utility of LA lowering in brain disorders should be exploredin future studies.

Involvement of Prostaglandins in the Pharmacological Actions of L‐Cysteine in Ocular Tissues

Evidence from our laboratory demonstrates that hydrogen sulfide (H2S) can exert pharmacological actions in ocular tissues, an effect that can be blocked by inhibitors of cyclooxygenase (COX).PurposeTo investigate whether H2S (using L‐cysteine as substrate) can alter prostaglandin E2 (PGE2) production in isolated bovine irides and retina.MethodsIsolated bovine irides and retinae were incubated in oxygenated Krebs buffer for 30 mins, prior to treatment with different concentrations of L‐cysteine (1 nM ‐ 10 µM) and norepinephrine (NE, 1 µM). After incubation and termination of reaction, tissues were homogenized and both homogenates and incubation media were collected and prepared for PGE2 Enzyme‐immunoassay (EIA) using a well‐established methodology.ResultsIn both bovine isolated irides and retinae, L‐cysteine elicited a concentration‐dependent (1 nM ‐ 10 µM) increase in PGE2 concentrations over basal levels. For instance, L‐cysteine (10nM; irides) and (10 µM; retina) produced an equi‐effective significant (p&lt; 0.05) increase in PGE2 concentrations over basal levels. In bovine irides (but not retinae), L‐cysteine (10 µM) produced an increase in PGE2 levelsin the incubation media indicating a washout of prostanoids from tissues exposed to L‐cysteine. The positive control, NE (1µM) also caused an increase in PGE2 concentrations over basal levels in ocular tissues.ConclusionL‐cysteine can increase prostaglandin production in isolated bovine irides and retinae, affirming a role for these autacoids in the pharmacology of H2S in the eye.

Correlation study of chronic nonbacterial prostatitis with the levels of COX-2 and PGE2 in prostatic secretion.

The prostatitis syndrome is a multifactorial condition of largely unknown etiology. This study is to analyze the relationship between cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) with the chronic nonbacterial prostatitis (CNBP). A total of 172 CNBP patients and 151 healthy males were recruited as CNBP and control group, respectively. The prostatic fluid was collected and tested by pre- and post-massage test. White blood cell (WBC) number was counted, and the contents of COX-2 and PGE2 were determined by double antibody-based sandwich enzyme-linked immuno-sorbent assay. The pain and discomfort of each patient were scored according to the National Institutes of Health chronic prostatitis symptom index. Compared with the control group, CNBP group displayed significantly higher WBC count, COX-2 level, and PGE2 level. Contents of COX-2 and PGE2 in prostatic secretion of CNBP group were positively correlated with pain scores (r = 0.855 and 0.675, respectively, P < 0.01) and total symptom scores (r = 0.674 and 0.566, respectively, P < 0.01). A significantly positive correlation between COX-2 and PGE2 levels was also discovered (r = 0.493, P < 0.05). The WBC number was not obviously correlated with the accumulations of COX-2 and PGE2 or the clinic symptoms of CNBP. Increase in PGE2 concentration caused by activated COX-2 pathway may contribute to the pain or discomfort symptom of the CNBP patients. Our results indicate that selective COX-2 inhibitors have application prospect in CNBP treatment.

Phospholipase A2, prostaglandin E2 and polyunsaturated fatty acid metabolic abnormalities in multiple sclerosis

AbstractAimMetabolic abnormalities reported in patients with multiple sclerosis include a decrease in cell membrane fatty acid C20:4n‐6. The aim of the present study was to investigate whether this decrease was associated with abnormalities in the prostaglandin E2 pathway in patients with multiple sclerosis.MethodsThe study population included 31 patients with multiple sclerosis and 30 healthy controls. Peripheral blood mononuclear cell membrane fatty acids were measured by gas chromatography, secretory‐phospholipase A2, and prostaglandin E2 with enzyme‐linked immunosorbent assays and C‐reactive protein with a Beckman auto‐analyser.ResultsProstaglandin E2 was increased in patients (545.5 pg/mL; quartile range 585.1 pg/mL) and controls (248.2 pg/mL; quartile range 183.6 pg/mL; P = 0.0018). Phospholipase A2 was inversely associated with C20:4n‐6 in patients and controls, respectively (P = 0.0398 and P = 0.0182). C‐reactive protein showed a positive association with phospholipase A2 in patients (P = 0.0006), and an inverse association with prostaglandin E2 in controls (P = 0.0006).ConclusionsThe increase in prostaglandin E2 concentration in plasma from patients with multiple sclerosis was possibly enhanced by the positive association between the C‐reactive protein and phospholipase A2 concentrations present in patients; that is, active stimulation of the prostaglandin E2 pathway, which can possibly explain decreases in membrane n‐6 fatty acid C20:4n‐6 reported in cell membranes from patients. It is not clear from the results of the present study whether this denotes chronic inflammation in patients, but could be expected to contribute to central nervous system damage reported in patients with multiple sclerosis.

Flow-induced prostaglandin E2 release regulates Na and K transport in the collecting duct

Fluid shear stress (FSS) is a critical regulator of cation transport in the collecting duct (CD). High-dietary sodium (Na) consumption increases urine flow, Na excretion, and prostaglandin E(2) (PGE(2)) excretion. We hypothesize that increases in FSS elicited by increasing tubular flow rate induce the release of PGE(2) from renal epithelial cells into the extracellular compartment and regulate ion transport. Media retrieved from CD cells exposed to physiologic levels of FSS reveal several fold higher concentration of PGE(2) compared with static controls. Treatment of CD cells with either cyclooxygenase-1 (COX-1) or COX-2 inhibitors during exposure to FSS limited the increase in PGE(2) concentration to an equal extent, suggesting COX-1 and COX-2 contribute equally to FSS-induced PGE(2) release. Cytosolic phospholipase A2 (cPLA2), the principal enzyme that generates the COX substrate arachidonic acid, is regulated by mitogen-activated protein-kinase-dependent phosphorylation and intracellular Ca(2+) concentration ([Ca(2+)](i)), both signaling processes, of which, are activated by FSS. Inhibition of the ERK and p38 pathways reduced PGE(2) release by 53.3 ± 8.4 and 32.6 ± 11.3%, respectively, while antagonizing the JNK pathway had no effect. In addition, chelation of [Ca(2+)](i) limited the FSS-mediated increase in PGE(2) concentration by 47.5 ± 7.5% of that observed in untreated sheared cells. Sheared cells expressed greater phospho-cPLA2 protein abundance than static cells; however, COX-2 protein expression was unaffected (P = 0.064) by FSS. In microperfused CDs, COX inhibition enhanced flow-stimulated Na reabsorption and abolished flow-stimulated potassium (K) secretion, but did not affect ion transport at a slow flow rate, implicating that high tubular flow activates autocrine/paracrine PGE(2) release and, in turn, regulates flow-stimulated cation transport. In conclusion, FSS activates cPLA2 to generate PGE(2) that regulates flow-mediated Na and K transport in the native CD. We speculate that dietary sodium intake modulates tubular flow rate to regulate paracrine PGE(2) release and cation transport in the CD.

Colloidal bismuth subcitrate causes sustained release of gastric mucosal prostaglandin E2

Gastric application of high doses of colloidal bismuth subcitrate (CBS) stimulates mucosal prostaglandin E2 (PGE2) production, which is considered part of the mechanism by which the drug accelerates peptic ulcer healing. Whether therapeutic, orally administered, doses of CBS cause a sustained stimulation of prostaglandin production is not known. We have, therefore, determined gastric luminal release of PGE2 during 'steady-state' perfusion of the stomach with CBS (10 mg/ml; isotonic mannitol 5 ml/min) and 4 h after the last oral dose of the drug (240 mg b.d.) for 2 weeks (isotonic mannitol 5 ml/min) in 8 healthy volunteers. A significant increase in PGE2 concentrations (712 (409-1076) vs. control 334 (252-655) pg/ml; medians with Q50 ranges; P less than 0.02) and PGE2 output (12.5 (7.3-14.3) vs. control 4.8 (4.1-7.3) ng/15 min; P less than 0.02) occurred during gastric perfusion with CBS. A similar increase in PGE2 concentrations (630 (297-1429) pg/ml; P less than 0.02) and PGE2 output (12.6 (6.4-22.2) ng/15 min; P less than 0.02) was observed following treatment with CBS for 2 weeks. These results suggest that therapeutic doses of CBS cause a sustained stimulation of gastric mucosal PGE2 formation.

Effect of cyclooxygenase-2 inhibitor pretreatment on gas exchange after hydrochloric acid aspiration in rats

The present study was carried out to determine the effect of cyclooxygenase-2 (COX-2) inhibitor on acid aspiration-induced lung injury in rats. Rats were allocated into one of four groups. Group H received intratracheal instillation of HCl. Group S received saline intratracheally. Group HC received COX-2 inhibitor (celecoxib) 10 mg/kg intravenously 30 min before intratracheal instillation of HCl. Group C underwent bronchoalveolar lavage (BAL) only. All rats were mechanically ventilated for 30 min before BAL. Arterial blood gas analysis was done immediately before BAL. Groups H, S, and HC were subdivided to each two groups. Groups H-1, S-1, and HC-1 underwent BAL 1 h after instillation, whereas groups H-8, S-8, and HC-8 underwent BAL 8 h after instillation. The BAL fluid was used to measure the prostaglandin E2 (PGE2) concentration. Intratracheal HCl resulted in impaired oxygenation. COX-2 inhibitor attenuated the impairment of oxygenation 8 h after instillation but not after 1 h. Intratracheal HCl caused an increase in PGE2 concentration. COX-2 inhibitor attenuated an increase in PGE2 concentration 8 h after instillation but not after 1 h. The results show that COX-2 inhibitor attenuates the oxygenation impairment and the increase in alveolar PGE2 concentration during the inflammatory phase of acid aspiration-induced lung injury in rats.

Ischaemia–Reperfusion Injury in the Isolated Haemoperfused Bovine Uterus: An In Vitro Model of Acute Inflammation

Following on from previous studies on dermal inflammation in the isolated perfused bovine udder, a new in vitro model of the isolated haemoperfused bovine uterus was established for studies on acute inflammatory reactions (for example, eicosanoid synthesis and regulation of cyclooxygenase-1 [COX-1] and COX-2) caused by ischaemia-reperfusion (I-R) injury. The organs and blood used in this study were obtained from a slaughterhouse. Within 2 hours of slaughter, uterine perfusion was re-established, by using a mixture of homologous blood and Tyrode solution (4:1). After equilibration, several deposits of arachidonic acid (5 mg and 0.1 mg) and arachidonylethanolamide (0.1 mg) were injected into the myometrial tissue. Tissue biopsies were taken from treated and untreated areas at 180 and 300 minutes after the onset of haemoperfusion, for measuring prostaglandin E(2) (PGE(2)) levels. In addition, the regulation of COX-1 and COX-2 mRNA was investigated by using the reverse transcriptase-polymerase chain reaction. Eicosanoid levels were determined by using an enzyme immunoassay (ELISA). Because both an increase in PGE(2) concentration and up-regulation of COX mRNA were observed, the inhibitory effects of dexamethasone, added to the perfusion medium, were studied. Dexamethasone caused a significant decrease in tissue PGE(2) production, but did not induce down-regulation of COX-2 mRNA. In conclusion, the isolated haemoperfused bovine uterus was introduced as an in vitro model of acute inflammation, induced by I-R injury. The suitability of the model for investigating anti-inflammatory substances was demonstrated. Use of the isolated haemoperfused bovine uterus in pharmacological research and drug screening may contribute to reducing the number of animals used for testing.

Role of prostaglandin receptor EP1 in the spinal dorsal horn in carrageenan-induced inflammatory pain.

Prostaglandin E2 (PGE2) and the receptor for PGE2 (EP receptor) are key factors contributing to the generation of hyperalgesia caused by inflammation. The current study was designed to investigate the roles of PGE2 and EP1 receptors in the spinal cord in the development and maintenance of inflammatory pain, using behavioral, microdialysis, and intracellular calcium ion concentration ([Ca2+]i) assays. Inflammation was induced by an injection of carrageenan into the plantar surface of the rat hind paw. The effects of inflammation were evaluated at the time points of 3 h (early phase) and 15 h (late phase) after carrageenan injection. In behavioral assays, withdrawal thresholds to mechanical stimuli were evaluated. The effect of an intrathecally administered selective EP1 antagonist, ONO-8711, on the carrageenan-induced hyperalgesia was examined. Using a spinal microdialysis method, PGE2 concentration in the spinal dorsal horn was measured. In [Ca2+]i assays, we measured [Ca2+]i in the spinal dorsal horn in transverse spinal slices and examined the effects of pretreatment with ONO-8711. Sensitivities of the changes in [Ca2+]i to PGE2 perfusion were also assessed. Mechanical hyperalgesia and paw edema were observed in both the early and late phases. The hyperalgesia was inhibited by intrathecal ONO-8711 in the late, but not early, phase. The concentration of PGE2 in the spinal dorsal horn increased in the late phase. The [Ca2+]i in the dorsal horn increased on the ipsilateral side to the inflammation in the late, but not early phase. This increase was suppressed by the pretreatment with ONO-8711. Magnitude of the increase in [Ca2+]i on the ipsilateral side in response to PGE2 perfusion was greater in the late phase than in the early phase. The results suggested that activation of spinal EP1 receptors was crucial in the carrageenan-induced mechanical hyperalgesia in the late phase. It seems that some of the mechanisms underlying inflammation-induced plastic changes are mediated by time-dependent increase in PGE2 concentration, activation of EP1 receptors, and increase in [Ca2+]i in the spinal dorsal horn.

Monosymptomatic primary enuresis: differences between patients responding or not responding to oral desmopressin.

To evaluate the 24-h diuresis, urinary osmolality, plasma arginine vasopressin (AVP) and urinary prostaglandin E2 (PGE2) before and during desmopressin treatment in patients with monosymptomatic primary enuresis (MPE), and to investigate the possible depressor effect of desmopressin on the detrusor in such patients with urodynamically confirmed bladder instability. Seven healthy children (control group) and 11 consecutive patients with MPE (mean age 10.4 years, range 7-15) were assessed using laboratory tests, renal and bladder ultrasonography, and video-urodynamic investigations. A 24-h inpatient assessment with a controlled water intake of 20 mL/kg per day included determinations of diuresis, urinary osmolality, AVP and PGE2 in both normal children and those with MPE. After 30 days of treatment at optimal doses of desmopressin, all children were hospitalized and re-evaluated during desmopressin treatment; all completed 3 months of treatment at optimal doses. At the end of this period, patients whose symptoms improved by > or = 80% were defined as 'responders' while those in whom they did not were defined as 'non-responders'. After treatment, six of the 11 patients with MPE were 'responders' and five 'non-responders'. Urodynamic evaluation showed bladder instability in seven of the 11 patients with MPE but in those with bladder dysfunction, urodynamic studies carried out during desmopressin treatment showed no changes in detrusor activity. There were significant differences in the morning values of AVP between normal children and responders (P < 0.03), and between responders and non-responders (P < 0.02); none of the non-responders had AVP levels of < 2.5 pg/mL, while none of the responders exceeded this value. At midnight, responders had the lowest mean AVP and non-responders the highest; this correlated with the highest PGE2 value in the nonresponders at 00.00-08.00 hours. Non-responders had an overnight mean PGE2 level greater than that in normal subjects or responders. Polyuria occurred in all patients with MPE, independently of the response to desmopressin. Responders had the lowest AVP values over the 24 h; the morning AVP levels differentiated normal subjects from enuretic patients and responders from non-responders. In patients with MPE, clinically undetected bladder instability was unrelated to the results of treatment and there were no urodynamic changes during desmopressin treatment. The differences between enuretic patients suggested a different aetiology of MPE, probably related to an increase in PGE2 concentration and an antagonistic mechanism of action of AVP or desmopressin.

Peripheral noxious stimulation releases spinal PGE 2 during the first phase in the formalin assay of the rat

Injection of formalin (5%; 50 μl) into the dorsal surface of the hind paw of rats evoked a characteristic biphasic flinching behaviour of the injured paw accompanied by a significant increase in the interstitial prostaglandin E2 (PGE2) concentration of the dorsal lumbar spinal cord. Interestingly, the increase in PGE2 concentration was only observed during the first phase of the formalin behavioural response (during the 0–10 and 10–20 min microdialysis-sample). Saline paw injection did not have a significant effect on behaviour or on PGE2 concentration. These data suggest that spinal release of PGE2 is involved in nociceptive processing in the formalin-induced hyperalgesia model of the rat during the first but not second phase.

Effect of three sources of long-chain fatty acids on the plasma fatty acid profile, plasma prostaglandin E2 concentrations, and pruritus symptoms in hemodialysis patients

Patients with chronic renal failure exhibit plasma fatty acid patterns indicative of essential fatty acid deficiency. The plasma fatty acid profile of 25 hemodialysis patients with a history of pruritus symptoms indicated lower 20:3n-9 (eicosatrienoic acid), 20:4n-6 (arachidonic acid), and 20:5n-3 (eicosapentaenoic acid) concentrations; a higher 18:1n-9 (oleic acid) concentration; and above-normal ranges of prostaglandin E2 (PGE2) compared with 22 subjects chosen from a normal population. No significant difference in 22:6n-3 (docosahexaenoic acid) was shown between the hemodialysis patients and the normal subjects. The dietary intake of 20:5n-3 was higher and that of 18:1n-9 lower in the patients compared with the normal population group. In this 8-wk double-blind study the hemodialysis patients were randomly assigned to receive daily supplements of 6 g ethyl ester of either fish oil, olive oil, or safflower oil. At the end of 8 wk of treatment the fish oil group (FO group) had a greater decrease in 18:1n-9 (P < 0.05), greater increases in 20:5n-3 and 22:6n-3 (P < 0.01), and trends toward a greater decrease in 20:4n-6, a greater increase in PGE2 concentrations, and greater improvement in pruritus scores (0.10 > P > 0.05) compared with the other two groups. The increases in 20:5n-3 and 22:6n-3 in the FO group indicate compliance with fish oil supplementation. Results indicate that hemodialysis patients have abnormal fatty acid profiles and increased PGE2 values. Fish oil intervention changes the fatty acid profile and may improve the symptoms of pruritus.

Prostaglandin E 2 Production After Lamellar Keratectomy and Photorefractive Keratectomy

To compare the levels of prostaglandin E2 (PGE2) in corneal tissue after 193-nanometer excimer laser keratectomy and mechanical keratectomy with a microkeratome. Four rabbits underwent 193-nanometer excimer laser phototherapeutic keratectomy on one eye, and lamellar keratectomy with the microkeratome on the fellow eye. The corneas were harvested at 10 hours after the treatment and quantitated for PGE2 levels using an enzyme-linked immune assay. Control levels of PGE2 in untreated corneas were obtained from a previous study. Unoperated control corneas had low levels of PGE2 (1.79 +/- 1.0 pg/mL). Both surgical techniques resulted in a significant (p < .01) increase in PGE2. Corneas ablated mechanically with the microkeratome had an average PGE2 level of 15.48 +/-5.36 pg/mL, which represented an 8.6-fold increase compared to control; there was an additional 330% mean increase in PGE2 concentration in the laser-ablated corneas (51.29 +/- 36.08 pg/mL) compared to the corneas treated with mechanical lamellar keratectomy (p = .014). Mechanical and photochemical superficial keratectomies induce production of an inflammatory mediator, PGE2. The 193-nanometer excimer laser irradiation causes a greater increase of PGE2 production in the corneal tissue than does keratectomy with the microkeratome; this observation may support a role for cyclo-oxygenase inhibitors in postoperative therapy.

A Sensitive Bioassay for a Standard of Recombinant Interleukin-1α

Abstract A sensitive bioassay for recombinant interleukin-1α (rIL-1α) has been developed. The assay is based on prostaglandin E2 (PGE2) production by fibroblasts following stimulation with rIL-1α. The stimulated PGE2 levels are determined by radioimmunoassay. Three human fibroblast cell lines, WI38, HEL299 and HS68, were evaluated. The HS68 cells gave the most sensitive and reproducible response. The results from six experiments established that 400 ± 300 femtograms of rIL-1α stimulated a two-fold increase in PGE2 concentration over the background level.

The role of fetal membranes in regulating production, transport, and metabolism of prostaglandin E 2 during labor

Abstract The level of prostaglandin E2, a potent stimulator of myometrial contractions, increases in amniotic fluid during labor. We tested whether amniotic prostaglandin E2 crosses the reflected fetal membranes to the myometrium during labor. Disks of amnion, chorion-decidua, and amnion chorion-decidua from 10 term pregnancies before labor and nine vaginal deliveries after normal spontaneous labor were incubated in two-sided perfusion chambers in the absence or presence of 1 wmol/l_ indomethacin, or in the presence of a bolus of prostaglandin E2 and radiolabeled prostaglandin E2 added to the fetal chamber. Net amniotic prostaglandin E2 increased significantly (p = 0.003) after labor. However, there was no significant difference in prostaglandin E2 concentrations on the maternal side of amnion chorion-decidua between labor conditions. High-pressure liquid chromatography identified the transport of intact tritiated prostaglandin E2 across amnion but not across chorion-decidua or amnion chorion-decidua in which prostaglandin E2 was completely metabolized. Because of 15-hydroxyprostaglandin dehydrogenase activity in chorion, we suggest that amniotic prostaglandin E2 transport to the myometrium is impaired. Thus the increase in prostaglandin E2 production that occurs in amnion tissue after labor commences does not result in an increase in prostaglandin E2 concentration on the myometrial side of the fetal membranes in the in vitro preparation. (AM J OBSTET GVNECOL 1990;163:1632-40.)

The role of fetal membranes in regulating production, transport, and metabolism of prostaglandin E2 during labor

The level of prostaglandin E2, a potent stimulator of myometrial contractions, increases in amniotic fluid during labor. We tested whether amniotic prostaglandin E2 crosses the reflected fetal membranes to the myometrium during labor. Disks of amnion, chorion-decidua, and amnion chorion-decidua from 10 term pregnancies before labor and nine vaginal deliveries after normal spontaneous labor were incubated in two-sided perfusion chambers in the absence or presence of 1 wmol/l_ indomethacin, or in the presence of a bolus of prostaglandin E2 and radiolabeled prostaglandin E2 added to the fetal chamber. Net amniotic prostaglandin E2 increased significantly (p = 0.003) after labor. However, there was no significant difference in prostaglandin E2 concentrations on the maternal side of amnion chorion-decidua between labor conditions. High-pressure liquid chromatography identified the transport of intact tritiated prostaglandin E2 across amnion but not across chorion-decidua or amnion chorion-decidua in which prostaglandin E2 was completely metabolized. Because of 15-hydroxyprostaglandin dehydrogenase activity in chorion, we suggest that amniotic prostaglandin E2 transport to the myometrium is impaired. Thus the increase in prostaglandin E2 production that occurs in amnion tissue after labor commences does not result in an increase in prostaglandin E2 concentration on the myometrial side of the fetal membranes in the in vitro preparation. (AM J OBSTET GVNECOL 1990;163:1632-40.)

Prevention of chronic cerebral vasospasm in dogs with ibuprofen and high-dose methylprednisolone.

Severe chronic cerebral vasospasm was produced in dog basilar arteries by two injections, 2 days apart, of autologous blood into the cisterna magna of 25 dogs. Treatment with ibuprofen (n = 8) or high-dose methylprednisolone (n = 8) after the first injection of blood prevented or reduced angiographic vasospasm. Cerebrospinal fluid concentrations of prostaglandin E2, prostaglandin F2 alpha, 6-ketoprostaglandin F1 alpha (a metabolite of prostacyclin), and thromboxane B2 (a metabolite of thromboxane A2) were measured in both treated and untreated (n = 7) dogs. In untreated dogs, the level of prostaglandin E2 increased 94-fold by Day 8 after the first injection of blood and was strongly and positively correlated with the degree of angiographic vasospasm. Treatment with ibuprofen and high-dose methylprednisolone prevented or significantly reduced this increase in prostaglandin E2 concentration. Smaller increases in cerebrospinal fluid concentrations of thromboxane B2 and 6-ketoprostaglandin F1 alpha occurred after experimental subarachnoid hemorrhage; the magnitude of these increases was also reduced by ibuprofen or high-dose methylprednisolone treatment. In contrast, prostaglandin F2 alpha levels were not significantly altered during the study. These data show that enhanced prostaglandin E2 synthesis occurs during experimental subarachnoid hemorrhage, and the by-products generated in its synthesis may play a role in the pathogenesis of cerebral vasospasm.

Prostaglandin E2 level in tears during postoperative inflammation of the eye.

The concentration of prostaglandin E2 (PGE2) in tears was measured by a radio immuno assay technique in 25 persons before cataract extraction and during the post-operative period. In addition we studied the clinical signs of inflammation, the tear secretion rate, the content of polymorphonuclear leucocytes (PMNs) in tears, the bacteriology of the conjunctival sac and the central corneal thickness (CCT) during this period. We found pre-operative median level of PGE2 of 82 pg/ml and on the first post-operative day a significant rise in PGE2 concentration despite increased tearing. There was a tendency towards further gradual increase in PGE2 concentration until the 5th day and thereafter a decline to pre-operative level 12 days after surgery. The conjunctiva is proposed as a possible source of the PGE2 in tears. No significant correlation could be demonstrated between PGE2 levels and clinical signs of inflammation, CCT, PMN level, bacteriology or tear secretion rate.