Effect of vaginal washing before intravaginal dinoprostone insertion for labor induction: A randomized clinical trial.

AIM: Prostaglandins have a dual action of cervical ripening and induction of uterine contraction. This study was designed to compare the effectiveness of vaginal washing just before insertion of intravaginal dinoprostone. METHODS: A randomized controlled trial was conducted at the Zeynep Kamil Women and Children's Health Training and Research Hospital. One hundred and ninety-one women with singleton, term pregnancy who underwent labor induction were randomly assigned to two groups: Group 1 consisted of 95 pregnant women with vaginal washing before intravaginal dinoprostone (Propess system for slow release system of 10 mg of dinoprostone) insertion (study group), and 96 pregnant women constituted the control group who did not undergo vaginal washing before intravaginal dinoprostone insertion. A parallel randomized controlled trial was conducted with an allocation ratio of 1:1 to compare the effectiveness of vaginal washing before intravaginal dinoprostone insertion. RESULTS: The groups had similar mean age, body mass index, gestational age, gravidity, parity and Bishop score before agent insertion (P > 0.05). Duration of dinoprostone kept intravaginally, duration from the beginning of dinoprostone insert vaginally to the active phase of labor and duration from the time of intravaginal dinoprostone insertion to delivery were significantly longer in the control group (P < 0.05). Uterine hyperstimulation rate was significantly higher in study group compared to control group (P < 0.05). Meconium passage, fetal infection and neonatal intensive care unit admission were significantly higher in the control group (P < 0.05). CONCLUSION: Vaginal washing before intravaginal dinoprostone insertion may increase Prostaglandin E2 bioavailability as we found shorter duration and better outcome of labor induction in the present study.

Bioanalysis of sulprostone, a prostaglandin E2 analogue and selective EP3 agonist, in monkey plasma by liquid chromatography-tandem mass spectrometry.

Sulprostone is a potent prostaglandin E2 (PGE2) analogue and one of the first identified selective G-protein-coupled receptor 3 (EP3) agonists. It has been investigated as a potential antiulcer agent and frequently used in the research of EP3 antagonist. To assist pharmacokinetic and pharmacodynamic studies, a rapid and sensitive LC-MS/MS method was developed and qualified for the quantitation of sulprostone in monkey plasma. Using electrospray ionization mass spectrometry, an ammonium adduct in positive mode was chosen for analysis which had seven times of the sensitivity of the depronated ion in negative mode. Latanoprost, a prostaglandin F2α analogue, was used as the internal standard while good sensitivity and chromatography were obtained on a 2.6 µm core-shell column with pentafluorophenyl stationary phase. An assay dynamic range of 2 to 4000 ng/mL was achieved with a sample volume of 25 µL plasma on a Sciex API4000 instrument with simple protein precipitation. Several esterase inhibitors including sodium fluoride (NaF), phenylmethanesulfonyl fluoride (PMSF), diisopropylfluorophosphate (DFP), paraoxon and dichlorvos as well as wet ice conditions were explored for the stabilization of sulprostone in monkey plasma. The developed method was successfully applied for the evaluation of pharmacokinetics of sulprostone after intravenous administration of 0.5 mg/kg to cynomolgus monkey.

Cranial dural permeability of inflammatory nociceptive mediators: Potential implications for animal models of migraine.

Background Application of inflammatory mediators to the cranial dura has been used as a method to activate and sensitize neurons in the meningeal sensory pathway in preclinical behavioral studies of headache mechanisms. However, the relatively high concentrations and volumes used in these studies raise the question of whether the applied agents might pass through the dura to act directly on central neurons, thus bypassing the dural afferent pathway. Methods We used a radiolabeling approach to quantify the meningeal permeability of two of the inflammatory mediators, 5-HT and PGE2, when applied to the cranial dura as part of an inflammatory mixture used in preclinical headache models. Results Both agents could be detected in samples taken four hours after dural application in the cerebrospinal fluid (CSF) and, in measurements made only for PGE2, in the central nervous system (CNS) as well. Based on our measurements, we made estimates of the CSF and CNS levels that would be attained with the higher concentrations and volumes of 5HT and PGE2 that were exogenously applied in previous pre-clinical headache studies. These estimated levels were comparable to or larger than normal endogenous levels, potentially large enough to have physiological effects. Conclusions The finding that the cranial meninges are permeable to the two tested inflammatory mediators PGE2 and 5-HT raises some uncertainty about whether the behavioral changes observed in prior pre-clinical headache studies with these as well as other agents can be attributed entirely to the activation of dural nociceptors, particularly when the agents are applied at concentrations several orders of magnitude above physiological levels.

Prostaglandin transporter (OATP2A1/SLCO2A1) contributes to local disposition of eicosapentaenoic acid-derived PGE3.

Eicosapentaenoic acid (EPA)-derived prostaglandin E3 (PGE3) possesses an anti-inflammatory effect; however, information for transporters that regulate its peri-cellular concentration is limited. The present study, therefore, aimed to clarify transporters involved in local disposition of PGE3. PGE3 uptake was assessed in HEK293 cells transfected with OATP2A1/SLCO2A1, OATP1B1/SLCO1B1, OATP2B1/SLCO2B1, OAT1/SLC22A6, OCT1/SLC22A1 or OCT2/SLC22A2 genes, compared with HEK293 cells transfected with plasmid vector alone (Mock). PGE3 uptake by OATP2A1-expressing HEK293 cells (HEK/2A1) was the highest and followed by HEK/1B1, while no significantly higher uptake of PGE3 than Mock cells was detected by other transporters. Saturation kinetics in PGE3 uptake by HEK/2A1 estimated the Km as 7.202 ± 0.595 µM, which was 22 times higher than that of PGE2 (Km=0.331 ± 0.131 µM). Furthermore, tissue disposition of PGE3 was examined in wild-type (WT) and Slco2a1-deficient (Slco2a1(-/-)) mice after oral administration of EPA ethyl ester (EPA-E) when they underwent intraperitoneal injection of endotoxin (e.g., lipopolysaccharide). PGE3 concentration was significantly higher in the lung, and tended to increase in the colon, stomach, and kidney of Slco2a1(-/-), compared to WT mice. Ratio of PGE2 metabolite 15-keto PGE2 over PGE2 concentration was significantly lower in the lung and colon of Slco2a1(-/-) than that of WT mice, suggesting that PGE3 metabolism is downregulated in Slco2a1(-/-) mice. In conclusion, PGE3 was found to be a substrate of OATP2A1, and local disposition of PGE3 could be regulated by OATP2A1 at least in the lung.

Prostaglandin E(2) induces immediate migraine-like attack in migraine patients without aura.

BACKGROUND: Prostaglandin E(2) (PGE(2)) has been suggested to play an important role in the pathogenesis of migraine. In the present experiment we investigated if an intravenous infusion of PGE(2) would induce migraine-like attacks in patients with migraine. METHODS: Twelve patients with migraine without aura were randomly allocated to receive 0.4 µg/kg/min PGE(2) (Prostin(®)E2, dinoprostone) or placebo over 25 minutes in a two-way, crossover study. Headache intensity was recorded on a verbal rating scale, middle cerebral artery blood flow velocity (V(MCA)) was measured by transcranial Doppler (TCD) and diameter of the superficial temporal artery (STA) was obtained by c-series scan (Dermascan C). RESULTS: In total, nine migraine patients (75%) experienced migraine-like attacks after PGE(2) compared to none after placebo (p = 0.004). Seven out of 9 (58%) patients reported the migraine-like attacks during the immediate phase (0-90 min) (p = 0.016). Only two patients experienced the delayed migraine-like attacks several hours after the PGE(2) infusion stop (p = 0.500). The V(MCA) decreased during the PGE(2) infusion (p = 0.005) but there was no significant dilatation of the STA (p = 0.850). CONCLUSION: The migraine-like attacks during, and immediately after, the PGE(2) infusion contrast with those found in previous provocation studies, in which the other pharmacological compounds triggered the delayed migraine-like attacks several hours after the infusion. We suggest that PGE(2) may be one of the important final products involved in the generation of migraine attacks.

Vitreous nonsteroidal antiinflammatory drug concentrations and prostaglandin E2 levels in vitrectomy patients treated with ketorolac 0.4%, bromfenac 0.09%, and nepafenac 0.1%.

PURPOSE: To assess vitreous concentrations of nonsteroidal antiinflammatory drugs (NSAIDs) and prostaglandin E(2) in patients treated with NSAIDs before vitrectomy. METHODS: This was an investigator-masked, randomized, multicenter study. Patients received ketorolac 0.4% 4 times a day, bromfenac 0.09% 2 times a day, nepafenac 0.1% 3 times a day, or no NSAID for 3 days before surgery. Nonsteroidal antiinflammatory drugs and prostaglandin E(2) levels were determined in vitreous samples collected at the beginning of surgery. RESULTS: Thirty-one patients were included in the analyses. The mean (SD) vitreous concentrations were as follows: ketorolac 2.8 (3.2) ng/mL, bromfenac 0.96 (0.31) ng/mL, nepafenac 1.1 (0.6) ng/mL, and amfenac 2.0 (0.8) ng/mL aligned with the initial concentrations of the topical NSAIDs. Mean (SD) vitreous prostaglandin E(2) levels of the control patients and those treated with ketorolac 0.4%, bromfenac 0.09%, or nepafenac 0.1% were 270.6 (91.7) pg/mL, 189.6 (50.2) pg/mL, 247.2 (38.3) pg/mL, and 267.7 (99.7) pg/mL, respectively. Patients treated with ketorolac 0.4% had significantly lower prostaglandin E(2) levels than those treated with no NSAID (P = 0.047) or nepafenac 0.1% (P = 0.028). CONCLUSION: All three NSAIDs penetrated into the vitreous cavity. Topical therapy with ketorolac may lower preoperative vitreous prostaglandin E(2) levels, which may have a clinical impact on the management of prostaglandin-mediated diseases, including cystoid macular edema.

Long-term NSAID treatment directly decreases COX-2 and mPGES-1 production in the articular cartilage of patients with osteoarthritis.

OBJECTIVE: To simultaneously study the effect of a selective cyclooxygenase-2 (COX-2) inhibitor and that of a classic non-steroidal anti-inflammatory drug (NSAID) on the expression of pro-inflammatory genes in the cartilage of patients with severe knee osteoarthritis (OA) and in cultured human OA chondrocytes. METHODS: A 3-month clinical trial was carried out on 30 patients with severe knee OA scheduled for knee replacement surgery. Patients were randomized into two groups: patients treated with celecoxib (CBX) and patients treated with aceclofenac (ACF). OA patients who did not want to be treated served as the control group. After surgery, cartilage was processed for molecular biology studies. We also employed cultured chondrocytes from different OA patients to examine NSAID effects on pro-inflammatory gene expression in cells stimulated with interleukin (IL)-1beta. RESULTS: Both CBX and ACF inhibited COX-2, microsomal prostaglandin E synthase-1 (mPGES-1) and inducible nitric oxide synthase (iNOS) synthesis in the articular cartilage of OA patients. In cultured chondrocytes, both NSAID decreased COX-2 and mPGES-1 synthesis and prostaglandin E2 (PGE2) release induced by IL-1beta, while no effect was observed on nitric oxide or iNOS synthesis. In OA patients, only CBX decreased tumor necrosis factor alpha and IL-1beta expression in the cartilage, while both NSAID diminished IL-1beta induced cytokine synthesis in cultured OA chondrocytes. CONCLUSIONS: Both NSAID diminished PGE2 release and induced a decrease in COX-2 and mPGES-1 synthesis in the cartilage from OA patients and in OA chondrocytes. These data suggest that prolonged therapy with PGE2 blocking agents decreases PGE2 production not only by direct inhibition of COX-2 activity, but also by down-regulating COX-2 and mPGES-1 synthesis in the cartilage. However, CBX and ACF seem to have a different anti-inflammatory profile in controlling pro-inflammatory gene expression in the cartilage.

Discovery of novel prostaglandin analogs of PGE2 as potent and selective EP2 and EP4 receptor agonists.

Analogs of PGE(2) with introduction of diene groups at the omega-side chain have been synthesized and evaluated for their binding affinity for EP(2) and EP(4) receptors. An optimized analog (compound 9b) showed high potency and selectivity for the EP(4) receptor over other known receptors.

Multidrug resistance associated protein 2 mediates transport of prostaglandin E2.

BACKGROUND/AIM: Inactivation of prostaglandin E(2) (PGE(2)) in the liver is a rapid process and occurs mainly through beta-oxidation in the peroxisome of the hepatocyte. Biliary excretion of PGE(2) is also a means of elimination from the liver. We investigated the role of multidrug resistance-associated protein 2 (MRP2) in the transport of PGE(2). METHODS: Biliary PGE(2) elimination was measured in liver perfusions in Wistar and MRP2-deficient TR(-) rats. Furthermore, transport experiments were performed in membrane vesicles from human MRP2-infected Spodoptera frugiperda 21 (Sf21) insect cells. RESULTS: The liver perfusions showed a 3.5 times higher percentage of undegraded [(3)H]PGE(2) in bile of Wistar rats in comparison with MRP2 deficient (TR(-)) rats (3.6% vs. 1.1%, respectively; P<0.05). MRP2-mediated transport of the model substrate [(3)H]DNP-SG was inhibited by PGE(2). Half maximal inhibition was achieved at a concentration of approximately 15 microM PGE(2). In addition, [(3)H]PGE(2) uptake in these vesicles was detected, and determined to be ATP dependent. CONCLUSION: MRP2 mediates the transport of PGE(2) and its breakdown products. The biliary excretion of PGE(2) via MRP2 may contribute to rapid elimination of the prostaglandin but might also serve to relay prostaglandin signalling to the biliary tree.

Segmental heterogeneity of electrogenic secretions in human ascending colon and rectum.

AIMS: We have attempted to ascertain putative segmental differences in the secretory responses of the human ascending colon and rectum. METHODS: From the mucosal biopsy samples of two segments, the short-circuit current (I(sc)) and tissue resistance (R(te)) were compared under control conditions, as well as after the induction of secretion, using a modified Ussing chamber. We also performed semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) to detect and quantify transport proteins. RESULTS: The spontaneous I(sc) in the ascending colon was found to be greater than that in the rectum (P<0.01), whereas isobutylmethylxanthine/forskolin and carbachol (CCh) induced a greater rise in I(sc) in the rectum than in the ascending colon (P<0.05). When coupled with indomethacin pretreatment, the increase in Delta I(sc) after the addition of CCh and forskolin was significant as compared to that observed without pretreatment (P<0.05). However, in the rectum, the secretory response to CCh and forskolin was abolished to a significant degree by indomethacin (P<0.05). Moreover, these indomethacin-induced changes were reversed by the addition of PGE2. Upon semiquantitative RT-PCR analysis, the amounts of cystic fibrosis transmembrane regulator, KCNQ1, and CLCA1 mRNAs were not found to be different between the two segments. CONCLUSION: There was a clear segmental heterogeneity with regard to electrogenic secretion in the human colon, and this difference can be explained by differences in the ascending colon and rectum.

Local transfer of prostaglandin E2 into the ovary and its retrograde transfer into the uterus in early pregnant sows.

This study was designed to establish (a) whether prostaglandin E2 (PGE2) can reach the ovary and oviduct by a local pathway and what is the contribution of lymphatic vessels to this transfer, and (b) whether PGE2 can permeate from venous and lymphatic vessels of the mesometrium to arterial blood and be delivered to the uterine horn during maternal recognition of pregnancy in gilts. The reproductive tract was excised from gilts (n = 10) on day 14 after mating. The uterine horn was isolated with the ovary and broad ligament and perfused with warmed and oxygenated autologous blood. A total dose of 5.5 x 10(7) disintegrations per min (d.p.m.) (49 ng) [3H]PGE2 was infused into the small branches of the uterine vein on the broad ligament or into the lymphatic vessels. Frequent blood samples were collected from the branch of the uterine artery and from the venous effluent. Tissue samples were collected from the uterine horn, the ovary and the broad ligament. The concentration of [3H]PGE2 was significantly higher in the ovary (P < 0.001), oviduct (P < 0.01), endometrium (P < 0.01), myometrium (P < 0.001) and mesometrium (P < 0.001) after infusion of [3H]PGE2 into lymphatic vessels than into the branches of the uterine vein. In contrast, the concentration of [3H]PGE2 was significantly higher in arterial blood supplying the uterine horn (P < 0.01) and in the venous effluent (P < 0.001) after infusion of [3H]PGE2 into the branches of the uterine vein than into lymphatic vessels. These results demonstrated local transfer of [3H]PGE2 into the ovary, oviduct and uterine horn from lymphatic and venous vessels of the mesometrium. However, the efficiency of this transfer was considerably higher after infusion into lymphatic vessels than into branches of the ovarian vein. We conclude that the lymphatic pathway is a fundamental mechanism in the local transfer of PGE2 from the uterus to the ovary and oviduct during early pregnancy in the pig.

Pharmacokinetics of prostaglandins.

Naturally occurring prostaglandins (PGs) are rapidly metabolized in the human circulation. For clinical use a number of PG analogues have therefore been developed which are resistant to rapid inactivation. Among these are carboprost, gemeprost and misoprostol. Following intramuscular injection of carboprost, plasma levels peaked after 20 minutes and declined slowly thereafter. In amniotic fluid the half-life was between 31 and 37 hours. Gemeprost is administered vaginally, and maximum plasma levels were reached after 2-3 hours, with detectable levels for at least 6-8 hours. Pharmacokinetic data on misoprostol are available following oral, vaginal and sublingual administration. Following oral treatment, plasma levels peaked at about 30 minutes, while after vaginal administration of the tablets the levels increased gradually and reached maximum levels after 70-80 minutes, but remained detectable for a significantly longer time. After sublingual administration the peak concentration was the same as for oral treatment but declined significantly more slowly. Endocervical administration of PGE(2) might be regarded as a local therapy, while following vaginal administration increased plasma levels of metabolites can generally be found. The plasma profile varies with the vehicle used.

The protective effect of rebamipide on paracellular permeability of rat gastric epithelial cells.

BACKGROUND: Barrier function in gastric epithelial cells is essential for the gastric defence mechanism against acid back-diffusion into the mucosal layer. Our previous study indicated that trans-epithelial resistance (TER) of rat gastric epithelial cells was rapidly increased when the cells were exposed to acid. This response to acid was diminished by indometacin. AIM: Evaluate the effects of a mucoprotective agent, rebamipide, on the nonsteroidal anti-inflammatory drug (NSAID)-induced increase of gastric epithelial permeability. METHODS: Rat gastric epithelial cells were plated on tissue culture inserts. Cells were exposed to a NSAID (indometacin, 10-7 M). Trans-epithelial permeability was measured by TER and diffusion rate of 14C-mannitol. The effect of rebamipide was evaluated by measuring TER. Endogenous prostaglandin E2 (PGE2) production in culture medium was also measured. RESULTS: Indometacin gradually and significantly decreased TER and increased 14C-manitol permeability. Rebamipide reversed the indometacin-induced changes in epithelial permeability and induced PGE2 synthesis. This induction was blocked by either indometacin or a Cyclooxygenase (COX)-2 specific inhibitor. CONCLUSIONS: COX inhibitors such as indometacin inhibit regulation of epithelial permeability by reducing PGE2. COX-1 has an important role in the gastric defense mechanism. Rebamipide suppressed an indometacin-induced increase in gastric epithelial permeability by increasing PGE2 levels in a COX-2 dependent manner.

Identification of lactate as a driving force for prostanoid transport by prostaglandin transporter PGT.

We previously characterized the prostaglandin (PG) transporter PGT as an exchanger in which [(3)H]PGE(2) influx is coupled to the efflux of a countersubstrate. Here, we cultured HeLa cells that stably expressed human PGT under conditions known to favor glycolysis (glucose as a carbon source) or oxidative phosphorylation (glutamine as a carbon source) and studied the effect on PGT-mediated [(3)H]PGE(2) influx. PGT-expressing cells grown in glutamine exhibited a 2- to 4-fold increase in [(3)H]PGE(2) influx compared with the antisense control, whereas cells grown in glucose exhibited a 14-fold increase. In the presence of 10 vs. 25 mM glucose during the uptake, there was a dose-dependent increment in [(3)H]PGE(2) influx. Cis inhibition of [(3)H]PGE(2) influx occurred with lactate at physiological concentrations (apparent K(m) = 48 +/- 12 mM). Preloading with lactate caused a dose-dependent trans stimulation of PGT-mediated [(3)H]PGE(2) uptake, and external lactate caused trans stimulation of PGT-mediated [(3)H]PGE(2) release. Together, these data are consistent with PGT-mediated PG-lactate exchange. Cells engaged in glycolysis would then be poised energetically for prostanoid uptake by means of PGT.

Cytokines and cytokine inducers stimulate prostaglandin E2 entry into the brain.

Cytokine inducers and cytokines increase the circulating level of prostaglandin E2 (PGE2) during the acute-phase immune response. This occurs simultaneously with the onset of fever, indicating that brain levels of PGE2 also increase. This raises the possibility that PGE2 produced in the peripheral circulation, not necessarily at distant sites from the brain, may penetrate the brain and be present in the cerebrospinal fluid (CSF). Blood and CSF levels of PGE2 in rabbits were measured by radioimmunoassay during fever stimulated in response to lipopolysaccharide (LPS), polyinosinic:polycytidylic acid (poly I:C) and interleukin-1 (IL-1) given i.v. The effect of the prostaglandin synthesis inhibitor ketoprofen on these parameters was also studied. In addition, the level of radioactivity in the CSF was measured following the administration of [125I]-labelled PGE2 i.v. during fever induced by LPS, poly I:C, IL-1 or tumor necrosis factor alpha (TNFalpha). Both LPS and poly I:C stimulated an increase in plasma and CSF levels of PGE2 over a 5-h period with a peak at 60 min and 90 min, respectively, which occurred in parallel with the changes in body temperature. Ketoprofen abolished the rise in plasma and CSF PGE2 levels and the rise in body temperature in response to LPS, poly I:C and IL-1. In experiments where animals were given [125I]-labelled PGE2 i.v., radioactivity well above the background level was measured in samples of CSF collected from LPS-, poly I:C-, IL-1- or TNFalpha-pretreated animals. In contrast the radioactivity present in samples of CSF perfusate collected from control (saline-treated) animals was indistinguishable from the background level. These data indicate that cytokine inducers and cytokines increase the mass level of PGE2 in blood and CSF and also increases the entry, from the peripheral circulation, of radiolabelled PGE2 into the third cerebral ventricle.

Metabolism of prostaglandin glycerol esters and prostaglandin ethanolamides in vitro and in vivo.

Prostaglandin glycerol esters (PG-Gs) and prostaglandin ethanolamides (PG-EAs) are generated by the action of cyclooxygenase-2 on the endocannabinoids 2-arachidonylglycerol (2-AG) and arachidonylethanolamide, respectively. These novel eicosanoids may have unique pharmacological properties and/or serve as latent sources of prostaglandins at sites remote from their tissue of origin. Therefore, we investigated the metabolism of PG-Gs and PG-EAs in vitro and in vivo. PGE(2)-G was rapidly hydrolyzed in rat plasma to generate PGE(2) (t(1/2) = 14 s) but was only slowly metabolized in human plasma (t(1/2) > 10 min). An intermediate extent of metabolism of PGE(2)-G was observed in human whole blood (t(1/2) approximately 7 min). The parent arachidonylglycerol, 2-AG, and the more stable regioisomer, 1-AG, also were much more rapidly metabolized in rat plasma compared with human plasma. PGE(2)-EA was not significantly hydrolyzed in plasma, undergoing slow dehydration/isomerization to PGB(2)-EA. Both PGE(2)-G and PGE(2)-EA were stable in canine, bovine, and human cerebrospinal fluid. Human 15-hydroxyprostaglandin dehydrogenase, the enzyme responsible for the initial step in PG inactivation in vivo, oxidized both PGE(2)-G and PGE(2)-EA less efficiently than the free acid. The sterically hindered glyceryl prostaglandin was the poorest substrate examined in the E series. Minimal 15-hydroxyprostaglandin dehydrogenase oxidation of PGF(2 alpha)-G was observed. PGE(2)-G and PGE(2)-EA pharmacokinetics were assessed in rats. PGE(2)-G was not detected in plasma 5 min following an intravenous dose of 2 mg/kg. However, PGE(2)-EA was detectable up to 2 h following an identical dose, displaying a large apparent volume of distribution and a half-life of over 6 min. The results suggest that endocannabinoid-derived PG-like compounds may be sufficiently stable in humans to exert actions systemically. Furthermore, these results suggest that the rat is not an adequate model for investigating the biological activities of 2-arachidonylglycerol or glyceryl prostaglandins in humans.

Aqueous flare elevation induced by transcorneal application of highly selective agonists for prostaglandin E2 receptor subtypes in pigmented rabbits: effect of tetramethylpyrazine.

We examined the disruptive effect of highly selective agonists for prostaglandin E2 receptor subtypes (EP1, EP2, EP3 and EP4) on the blood-aqueous barrier, and evaluated the inhibitory effect of tetramethylpyrazine, an active component of Ligusticum wallichii, on the elevation of aqueous flare induced by the EP agonists in pigmented rabbits. Highly selective EP agonists (ONO-DI-004, EP1 agonist; ONO-AE1-259-01, EP2 agonist; ONO-AE-248, EP3 agonist; ONO-AE1-329, EP4 agonist) at 12.5 to 250 microg/ml were transcorneally administered to the eyes of pigmented rabbits using a glass cylinder. Animals were pretreated intravenously with tetramethylpyrazine (10 or 30 mg/kg) 30 minutes before application of the EP2 or the EP4 agonist. Aqueous flare was measured using a laser flare-cell meter. Aqueous flare intensity was expressed as the area under the curve (AUC) in arbitrary units. After administration of ONO-AE1-259-01 or ONO-AE1-329, aqueous flare increased and then gradually decreased. ONO-DI-004 and ONO-AE-248 had almost no effect on aqueous flare elevation. The AUC of eyes in rabbits pretreated with tetramethylpyrazine, 10 or 30 mg/kg i.v., was significantly smaller than that of eyes in rabbits treated with ONO-AEI-259-01 alone. The AUC of eyes in rabbits pretreated with tetramethylpyrazine, 10 or 30 mg/kg i.v., was not significantly smaller than that of eyes in rabbits treated with ONO-AEI-329 only. The results indicated that EP2 and EP4 agonists induced aqueous flare elevation in pigmented rabbits, and that tetramethylpyrazine inhibited the aqueous flare elevation induced by the EP2 agonist but did not suppress the elevation induced by the EP4 agonist.

In vivo controlled release of PGE2 from a vaginal insert (0.8 mm, 10 mg) during induction of labour.

OBJECTIVE: To measure the release rate of prostaglandin E2 (PGE2) in vivo from a controlled-release vaginal insert used for cervical ripening and induction of labour at term in women with intact membranes or pre-labour rupture of membranes (PROM). DESIGN: Open-label, single centre study. POPULATION: Women at term (> or = 37 gestational weeks) with unripe cervices (Bishop score < or = 6) scheduled for labour induction for mainly medical reasons. METHODS: sixty-eight women (47 with intact membranes and 21 with PROM) had the PGE2 vaginal insert placed in the posterior fornix of the vagina. Each insert was removed from the women at a predetermined time interval between 0.5 h and 24 h, or earlier if labour was induced, fetal distress was detected or maternal complications occurred. After removal, the vaginal insert was frozen and stored for subsequent assay of residual PGE2. Blood samples were collected immediately before insertion and at 4-hour intervals until removal of the vaginal insert to determine plasma concentrations of PGE2 and the major PGE metabolite, 15-Keto-13, 14-dihydro-PGF2alpha (PGEm). Vaginal pH was measured immediately before insertion and directly after removal of the vaginal insert. Bishop score was assessed before induction, after 8 h, 12 h and immediately after removal of the vaginal insert. RESULTS: There was a positive linear relationship between the amount of PGE2 released from the insert and the duration of treatment in women with intact membranes (rp = 0.95, P = 0.0001), with a calculated PGE2 release rate of 0.52 +/- 0.33 mg/h over 24 h. The PGE2 release rate in women with PROM was not linear. The PGE2 release rate was dependent on vaginal pH, with a faster release rate at higher vaginal pH. Forty-seven women (69.1%) had the insert removed due to the successful induction of labour and consequently discontinued study treatment before their allocated time period. At vaginal delivery, the released amount of PGE2 at onset of labour was 4.0 +/- 3.0 mg and 2.4 +/- 2.1 mg for nulliparous women with PROM and intact membranes, respectively (P = 0.1). In multiparous women, the equivalent mean released amount was 3.2 +/- 2.6 mg and 1.9 +/- 1.4 mg, respectively (P = 0.14). In women with intact membranes, the mean plasma concentrations of PGE2 and PGEm after treatment were not statistically different to those women with PROM (P = 0.27 and 0.64, respectively). In women who were delivered vaginally, the median induction to delivery time interval was 17.0 h (range 4-42) in nulliparous women and 8.7 h (range 5-19) in multiparous women (P = 0.003). Ten (14.7%) women, who were all nulliparous, were delivered by caesarean section. CONCLUSIONS: In women with intact membranes, the PGE2 release rate was linear over 24 hours. There was a positive linear relationship between vaginal pH and PGE2 release rate. The metabolite analysis revealed no evidence of dose dumping neither in women with intact membranes or in women with PROM.

Functional analysis and androgen-regulated expression of mouse organic anion transporting polypeptide 1 (Oatp1) in the kidney.

Mouse Oatp1 was recently identified as a new murine member of the organic anion transporting polypeptide (Oatp) family and suggested to represent the counterpart of rat Oatp1. Northern blot analysis detected expression of several mouse Oatp-transcripts predominantly in liver and kidney. In the present study we describe the strict androgen-dependent expression of mouse Oatp1 mRNA in kidney and obtained further information about its substrate specificity using Xenopus oocytes. In addition to the previously reported estrone-3-sulfate, we demonstrate that mouse Oatp1 mediates sodium-independent uptake of the anionic steroid conjugates dehydroepiandrosterone sulfate (K(m) approximately 8 microM) and estradiol-17-glucuronide (K(m) approximately 5 microM) and also of the prostaglandin PGE(2).

Disruption of the blood-aqueous barrier following retinal laser photocoagulation and cryopexy in pigmented rabbits.

Disruption of the blood-aqueous barrier (BAB) induced by retinal photocoagulation and cryopexy in pigmented rabbits was evaluated by laser flare photometry. A significant increase in flare values after retinal photocoagulation was measured from the 1st postoperative day, with values returning to baseline levels by day 7. Cryopexy induced consistently high flare values for 14 days. Intravitreal injection of interleukin (IL) 1, IL-6 and prostaglandin (PG) E(2) induced a significant increase in flare values. Following these treatments, introduction of a PG synthetase inhibitor can partially ameliorate BAB disruption. IL-1, IL-6 and PGE(2) may be involved in BAB disruption following retinal photocoagulation and cryopexy.