Prostaglandin Inhibition Research Articles

In search of a vasodilator: is ATP the answer?

Control of the blood flow to various tissues and organs of the body has received major attention for more than a century. Some progress has been made towards the identification of mechanisms and possible compounds that contribute to the precise control of muscle hyperaemia to match O2 delivery with tissue demands. Just making a list of all the compounds that have been proposed through the years would fill a page. There are three key control sites for the regulation of the microcirculatory blood flow: (a) inhibition of sympathetic vasoconstrictor activity, mediated by noradrenaline (NA) and its binding to alpha receptors on smooth muscle cells, (b) dilatation of small feeding arterioles by conducted (ascending), vasodilatation and (c) smooth muscle local relaxation. When nitric oxide (NO) was first shown to be the regulator of resting smooth muscle tonus, it was soon believed to play a similar role in regulating the vasodilatory response. NO is a vasodilator, but in contracting skeletal muscle its role is limited. Prostaglandins (PGs) closely interact with NO and thereby also contribute to the exercise hyperaemia, but the total effect is far from a maximum blood flow response. In the recent article in The Journal of Physiology by Crecelius et al. (2012) they confirm that these two vasodilators are insufficient to explain observed peak perfusion, but of greater importance is that they not only demonstrate that luminal ATP is a powerful dilator but also that the likely mechanism by which ATP works – and in accordance with data from in vitro studies of various animal models – is to hyperpolarize the endothelium, an effect that is subsequently transferred to the smooth muscle cells, thereby affecting both ascending and local vasodilatation ((b) and (c), above). The experiments were performed on the forearm of humans by infusing various combinations of NO and PG inhibitors with ATP, and using ouabain and BaCl2 to block Na+/K+–ATPase and the inwardly rectifying potassium channels (KIR), respectively. The blood flow of the forearm was measured with venous occlusion plethysmography (VOP), which has been the common method in these types of studies in the past, but in spite of its common use, VOP is not ideal for the determination of blood flow. However, the observed blood flow changes are convincing and provide support that the likely mechanism, also in humans, is an ATP-mediated vasodilatation, which occurs with the binding of ATP to P2y receptors on the endothelial cells. This binding to the receptor induces hyperpolarization by the activation of Na+/K+–ATPase and Kir (Fig. 1). A question may be raised about how well the forearm represents other microvascular regions of the human body (Newcomer et al. 2004). In regard to the effect of luminal ATP and the K+ kinetics it may be the same in the leg. In a study by Juel et al. (2007) potassium was infused in the femoral artery with and without BaCl2. The effect of the KIR blocker was similar to the one reported by Crecelius et al. (2012). Figure 1 Schematic illustration of how luminal ATP release, primarily from red blood cells via P2y receptors on the endothelial cells, induces hyperpolarization, which is subsequently transferred to the smooth muscle cells, thereby eliciting both ascending and ... The present findings of a major vasodilatory role of luminal ATP open up a redirection of the research focus, from NO and PG to ATP, via P2y receptors induced intracellular signalling within the endothelial cells and further to the smooth muscle cells, but also to the availability of ATP. Endothelial cells produce and release ATP, but the ATP in the luminal space, binding to endothelial P2y receptors, is commonly believed to be released from the red blood cells (Ellsworth et al. 2009). The situation is complex, however, as this release of ATP from red blood cells appears not always to be mandatory for an appropriate vasodilatation to occur. In the interstitial space of contracting skeletal muscles, ATP is elevated to levels above what is observed in the vascular space, but an exchange between the interstitial and luminal space is unlikely. Recently, a role for interstitial ATP has been proposed, which could be to act as the blocking compound of NA vasoconstrictor activity (functional sympatholysis (a) above), and P2y receptors are also present on cells in the interstitial space (Hellsten et al. 2012). Thus, combining these possibilities with the demonstration by Crecelius and colleagues of a marked ATP-induced vasodilatory effect through hyperpolarization of the vascular cells provide a basis for and inspiration to further document that ATP really is a key player in skeletal muscle vasodilatation.

Ts6 and Ts2 from Tityus serrulatus venom induce inflammation by mechanisms dependent on lipid mediators and cytokine production

Inflammatory mediators are thought to be involved in the systemic and local immune response induced by the Tityus serrulatus scorpion envenomation. New functional aspects of lipid mediators have recently been described. Here, we examine the unreported role of lipid mediators in cell recruitment to the peritoneal cavity after an injection with Ts2 or Ts6 toxins isolated from the T. serrulatus scorpion venom. In this report, we demonstrate that following a single intraperitoneal (i.p.) injection of Ts2 or Ts6 (250 μg/kg) in mice, there was an induction of leukocytosis with a predominance of neutrophils observed at 4, 24, 48 and 96 h. Moreover, total protein, leukotriene (LT)B4, prostaglandin (PG)E2 and pro-inflammatory cytokine levels were increased. We also observed an increase of regulatory cytokines, including interleukin (IL)-10, after the Ts2 injection. Finally, we observed that Ts2 or Ts6 injection in 5-lipoxygenase (LO) deficient mice and in wild type (WT) 129sv mice pre-treated with LTs and PGs inhibitors (MK-886 and celecoxib, respectively) a reduction the influx of leukocytes occurs in comparison to WT. The recruitment of these cells demonstrated a phenotype characteristic of neutrophils, macrophages, CD4 and CD8 lymphocytes expressing GR1+, F4/80+, CD3+/CD4+ and CD3+/CD8+, respectively. In conclusion, our data demonstrate that Ts2 and Ts6 induce inflammation by mechanisms dependent on lipid mediators and cytokine production. Ts2 may play a regulatory role whereas Ts6 exhibits pro-inflammatory activity exclusively.

Tocolytic therapy for preterm delivery: systematic review and network meta-analysis

Objective To determine the most effective tocolytic agent at delaying delivery.Design Systematic review and network meta-analysis.Data sources Cochrane Central Register of Controlled Trials, Medline, Medline In-Process, Embase, and CINAHL up...

Cyclooxygenase-2, Not Microsomal Prostaglandin E Synthase-1, Is the Mechanism for Interleukin-1β-induced Prostaglandin E2 Production and Inhibition of Insulin Secretion in Pancreatic Islets

Arachidonic acid is converted to prostaglandin E(2) (PGE(2)) by a sequential enzymatic reaction performed by two isoenzyme groups, cyclooxygenases (COX-1 and COX-2) and terminal prostaglandin E synthases (cPGES, mPGES-1, and mPGES-2). mPGES-1 is widely considered to be the final enzyme regulating COX-2-dependent PGE(2) synthesis. These generalizations have been based in most part on experiments utilizing gene expression analyses of cell lines and tumor tissue. To assess the relevance of these generalizations to a native mammalian tissue, we used isolated human and rodent pancreatic islets to examine interleukin (IL)-1β-induced PGE(2) production, because PGE(2) has been shown to mediate IL-1β inhibition of islet function. Rat islets constitutively expressed mRNAs of COX-1, COX-2, cPGES, and mPGES-1. As expected, IL-1β increased mRNA levels for COX-2 and mPGES-1, but not for COX-1 or cPGES. Basal protein levels of COX-1, cPGES, and mPGES-2 were readily detected in whole cell extracts but were not regulated by IL-1β. IL-1β increased protein levels of COX-2, but unexpectedly mPGES-1 protein levels were low and unaffected. In microsomal extracts, mPGES-1 protein was barely detectable in rat islets but clearly present in human islets; however, in neither case did IL-1β increase mPGES-1 protein levels. To further assess the importance of mPGES-1 to IL-1β regulation of an islet physiologic response, glucose-stimulated insulin secretion was examined in isolated islets of WT and mPGES-1-deficient mice. IL-1β inhibited glucose-stimulated insulin secretion equally in both WT and mPGES-1(-/-) islets, indicating that COX-2, not mPGES-1, mediates IL-1β-induced PGE(2) production and subsequent inhibition of insulin secretion.

Two in one against motor neuron degeneration: tackling oxidative stress and inflammation with a sulfasalazine derivative

Two in one against motor neuron degeneration: tackling oxidative stress and inflammation with a sulfasalazine derivative

Vasorelaxing effects of estetrol in rat arteries

This study compared ex vivo relaxing responses to the naturally occurring human hormone estetrol (E(4)) vs 17β-estradiol (E(2)) in eight different vascular beds. Arteries were mounted in a myograph, contracted with either phenylephrine or serotonin, and cumulative concentration-response curves (CRCs) to E(4) and E(2) (0·1-100 μmol/l) were constructed. In all arteries tested, E(4) had lower potency than E(2), although the differential effect was less in larger than smaller arteries. In uterine arteries, the nonselective estrogen receptor (ER) blocker ICI 182 780 (1 μmol/l) caused a significant rightward shift in the CRC to both E(4) and E(2), indicating that the relaxation responses were ER dependent. Pharmacological blockade of nitric oxide (NO) synthases by N(ω)-nitro-L-arginine methyl ester (L-NAME) blunted E(2)-mediated but not E(4)-mediated relaxing responses, while inhibition of prostaglandins and endothelium-dependent hyperpolarization did not alter relaxation to either E(4) or E(2) in uterine arteries. Combined blockade of NO release and action with L-NAME and the soluble guanylate cyclase (sGC) inhibitor ODQ resulted in greater inhibition of the relaxation response to E(4) compared with E(2) in uterine arteries. Endothelium denudation inhibited responses to both E(4) and E(2), while E(4) and E(2) concentration-dependently blocked smooth muscle cell Ca(2)(+) entry in K(+)-depolarized and Ca(2)(+)-depleted uterine arteries. In conclusion, E(4) relaxes precontracted rat arteries in an artery-specific fashion. In uterine arteries, E(4)-induced relaxations are partially mediated via an endothelium-dependent mechanism involving ERs, sGC, and inhibition of smooth muscle cell Ca(2)(+) entry, but not NO synthases or endothelium-dependent hyperpolarization.

Study of long effects of administration of aspirin (acetylsalicylic acid) on bone in broiler chickens

Tibial dyschondroplasia (TD) is considered to be a major production-related health and welfare problem in meat-type chickens and turkeys. One cause of such poultry leg problems is traced to a defect arising in the growing end of leg bones which partially fail to become bone, making the ends prone to breakage and infection. In this study, we investigate the possible role of prostaglandins and their deleterious effects on TD in broiler chickens, experimentally receiving dietary administration of aspirin. Fourteen male Ross chickens aged 1 day were divided into two groups to receive either only water or aspirin (400 mg/L) in the drinking water. Chickens were observed for clinical signs of lameness twice daily. None of the chickens in treatment and control groups showed clinical signs of lameness. However, histopathologic observations of tibiotarsal bones in treatment group showed vascular abnormality along with degenerative changes in chondrocytes at growth pales, attributed to over mineralization of the bone. In addition, alkaline phosphatase activity in treatment groups was decreased, suggesting TD in chickens receiving aspirin. In conclusion, our study showed that dietary administration of aspirin at dose of 400 mg/L for 21 days induced histopathological changes in broiler chickens. Inhibition of prostaglandins seems to contribute majorly with disruption of normal chondrocyte differentiation in growth plates of tibiotarsal bones in chickens receiving aspirin.

Direct peritoneal resuscitation augments ileal blood flow in necrotizing enterocolitis via a novel mechanism

PurposeEndothelin-1, prostaglandins (PGs), and nitric oxide (NO) have been implicated in the intestinal microvascular dysfunction of necrotizing enterocolitis (NEC). We hypothesized that direct peritoneal resuscitation (DPR) dilates the intestinal microvasculature and improves blood flow independent of these mechanisms. MethodsRat pups were assigned by litter to experimental NEC or CONTROL groups. Laser Doppler flowmetry evaluation of intestinal microvascular blood flow was studied at baseline, with mediator blockade (endothelin-A receptor, endothelin-B receptor, PG synthesis, or NO synthase) and with DPR. Repeated-measures analysis of variance test was applied with Tukey-Kramer honestly significant difference test (P < .05). ResultsAt baseline, NEC animals demonstrated significantly decreased ileal blood flow as compared with CONTROLs (P < .05). Endothelin-A receptor and PG inhibition increased flow in the intestinal microvasculature, but this was significantly augmented by the addition of DPR (P < .05). Blockade of NO synthase decreased intestinal blood flow, which was overcome with addition of DPR (P < .05). ConclusionIleal blood flow was significantly reduced in NEC animals as compared with CONTROLs. The addition of DPR to the peritoneum increased ileal blood flow significantly in all groups in spite of blockade of these known vasoactive mechanisms. Direct peritoneal resuscitation may be a novel strategy to improve intestinal blood flow in NEC.

Paracetamol (acetaminophen), aspirin (acetylsalicylic acid) and indomethacin are anti‐androgenic in the rat foetal testis

More than half the pregnant women in the Western world report taking mild analgesics. These pharmaceutical compounds have been associated with congenital cryptorchidism in humans, the best-known risk factor for low semen quality and testicular germ cell cancer. Furthermore, some of these mild analgesics exert potent anti-androgenic effects in the male rat and several endocrine-disrupting compounds, known to alter masculinization, have also been shown to be potent inhibitors of prostaglandin (PG) synthesis similar to mild analgesics. Using a 3-day ex vivo organotypic model system based on gestational day 14.5 rat testes, we herein show that testosterone production was inhibited by paracetamol, at doses of 0.1 μm to 100 μm. Similar results were obtained for aspirin (1-100 μm) and indomethacin (10 μm). The production of the other Leydig cell hormone, Insl3, was not disrupted by exposure to paracetamol. Investigations of the gross anatomy of the testis as well as Leydig cells number and rate of gonocyte apoptosis after the 3 days of ex vivo differentiation showed no significant effect of the analgesics tested compared with controls. These data indicate therefore that mild analgesics specifically inhibit testosterone production in rat foetal testes in vitro and that these compounds had no effect on gonocyte survival. Parallel determinations of prostaglandin D2 (PGD2) production indicated that the effects of paracetamol and aspirin on PGD2 and testosterone were not connected, whereas the effects of indomethacin were correlated. We conclude that mild analgesics exert direct and specific anti-androgenic effects in rat foetal testis in our experimental setup and that the mechanism of action is probably uncoupled from the inhibition of PG synthesis.

Opposing effects of nitric oxide and prostaglandin inhibition on muscle mitochondrial V̇o2 during exercise

Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through competitive binding to cytochrome-c oxidase. Indomethacin uncouples and inhibits the electron transport chain in a concentration-dependent manner, and thus, inhibition of NO and PG synthesis may regulate both muscle oxygen delivery and utilization. The purpose of this study was to examine the independent and combined effects of NO and PG synthesis blockade (L-NMMA and indomethacin, respectively) on mitochondrial respiration in human muscle following knee extension exercise (KEE). Specifically, this study examined the physiological effect of NO, and the pharmacological effect of indomethacin, on muscle mitochondrial function. Consistent with their mechanism of action, we hypothesized that inhibition of nitric oxide synthase (NOS) and PG synthesis would have opposite effects on muscle mitochondrial respiration. Mitochondrial respiration was measured ex vivo by high-resolution respirometry in saponin-permeabilized fibers following 6 min KEE in control (CON; n = 8), arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA; n = 4) and Indo (n = 4) followed by combined inhibition of NOS and PG synthesis (L-NMMA + Indo, n = 8). ADP-stimulated state 3 respiration (OXPHOS) with substrates for complex I (glutamate, malate) was reduced 50% by Indo. State 3 O(2) flux with complex I and II substrates was reduced less with both Indo (20%) and L-NMMA + Indo (15%) compared with CON. The results indicate that indomethacin reduces state 3 mitochondrial respiration primarily at complex I of the respiratory chain, while blockade of NOS by L-NMMA counteracts the inhibition by Indo. This effect on muscle mitochondria, in concert with a reduction of blood flow accounts for in vivo changes in muscle O(2) consumption during combined blockade of NOS and PG synthesis.

Acetaminophen and Ibuprofen Overdosage

Acetaminophen and Ibuprofen Overdosage

Acetaminophen and Ibuprofen Overdosage

Acetaminophen and Ibuprofen Overdosage

ATP‐mediated vasodilation occurs via vascular hyperpolarization in humans

ATP possesses unique vasomotor properties and has been hypothesized to contribute to the control of vascular tone under a variety of physiological conditions; however, in humans, the underlying vasomotor signaling mechanisms remain unknown. We sought to determine whether ATP‐mediated vasodilation occurs via vascular hyperpolarization in young healthy humans. In Protocol 1 (n=8), progressive doses of ATP and potassium chloride (KCl) were infused via brachial artery catheter. Forearm vascular conductance (FVC) was calculated from forearm blood flow (venous occlusion plethysmography) and intra‐arterial blood pressure to quantify local vasodilation. Vasodilatory responses (%ΔFVC) to ATP infusions were unchanged following combined inhibition of nitric oxide (NO) and prostaglandins (PGs; P&gt;0.05) whereas the response to KCl was significantly greater (P&lt;0.05). In Protocol 2 (n=21), infusion of both ouabain (to inhibit Na+/K+ ATPase) and barium chloride (BaCl2; to inhibit KIR channels) abolished KCl‐mediated vasodilation (%ΔFVC= 134±13 vs 4±5%; P&lt;0.05) indicating effective inhibition of vasodilation mediated via hyperpolarization. On average, forearm vasodilation to 3 doses of ATP was inhibited ~60% following combined ouabain+BaCl2 infusion. Our novel results indicate that the majority of vasodilation in response to ATP occurs via vascular hyperpolarization in humans. Supported by HL102720

Nitric oxide synthase (NOS) inhibition blunts the kinetics of vasodilation during dynamic forearm exercise

We tested the hypothesis that local inhibition of NOS would 1) alter the kinetics of vasodilation during dynamic forearm (FA) exercise and 2) prolong the time to reach steady state (SS). Subjects (n=22) performed rhythmic FA exercise (20% of maximum) during saline infusion (control) and NOS inhibition (L‐NMMA). Additionally, a subset of subjects performed a third trial of FA exercise during combined inhibition of either 1) NOS and adenosine (aminophylline; n=9), or 2) NOS and prostaglandins (Ketorolac; n=8). Forearm vascular conductance (FVC; ml/min/100mmHg) was calculated from blood flow (ml/min) and blood pressure (mmHg). Vasodilator kinetics were assessed by calculating the slope of the FVC response for every duty cycle between baseline and SS exercise as well as the number of duty cycles (1s contraction/2s relaxation) to reach SS. NOS inhibition reduced the kinetics of vasodilation during dynamic FA exercise (8.5 ± 0.6 vs. 11.1 ± 0.8 FVC/duty cycle; P &lt; 0.001 vs. control) and increased the time to reach SS (25.1 ± 1 vs. 32 ± 1 duty cycles; P &lt; 0.001 vs. control). The kinetics of vasodilation were reduced further with combined inhibition of NOS and adenosine (6.2 ± 0.8 vs. 7.5 ± 0.6 FVC/duty cycle; P &lt; 0.05 vs. L‐NMMA alone), but not with combined inhibition of NOS and prostaglandins. Our data indicate that NOS inhibition blunts the kinetics of vasodilation during dynamic FA exercise and prolongs the time to reach SS.

Inhibition of hydrogen peroxide, lipopolysaccharide and interleukin-1 beta-induced prostaglandin E-2 production in chondrocytes by the combination of avocado/soybean unsaponifiables and lipoic acid

s / Osteoarthritis and Cartilage 20 (2012) S54–S296 S241 Purpose: Rheumatoid arthritis (RA) synoviocytes present an increased mitochondrial genome mutagenesis, leading to mitochondrial alterations that might be participating in the pathogenesis of the disease. This study was performed to examine whether mitochondrial dysfunction is involved in joint destruction and inflammation in RA in relation to the expression of matrix metalloproteinases-1 and -3 (MMP-1 and MMP-3) and vascular endothelial growth factor (VEGF) in normal human synoviocytes. Methods: Normal human synoviocytes were treated with the commonly usedmitochondrial respiratory inhibitor oligomycin (OLI) (10 mg/ml) for 24 hours. As a positive control, MMPs and VEGF expression was induced by 5ng/ml interleukin-1b (IL-1b). MMPs and VEGFmRNA expression (RT-PCR) and MMP-1 protein levels (ELISA) were analyzed. The effect of the natural antioxidant resveratrol (RSV, 50 mM) was tested. Results: We found that oligomycin-induced mitochondrial dysfunction in synoviocytes for 24h significantly increased MMP-1 mRNA expression (835,7 480,4 vs. Basal 1, n1⁄46, p<0.05), evenmore than higher levels of the positive control IL-1b (580,3 343,2). This increase in MMP-1 mRNA expression was accompanied by the synthesis of MMP-1 protein (702

Combination of calcitriol and dietary soy exhibits enhanced anticancer activity and increased hypercalcemic toxicity in a mouse xenograft model of prostate cancer

The potential role of vitamin D and soy in prostate cancer (PCa) prevention/treatment has gained much attention in recent years. In this study, we evaluated the anticancer activity of calcitriol, the active form of vitamin D, dietary soy, and their combinations in a mouse model of PCa. Athymic male nude mice bearing PC-3 human PCa xenografts received diets containing 10 or 20 kcal% soy, calcitriol injections, or a combination of dietary soy and calcitriol. Changes in tumor growth, serum levels of 1,25(OH)(2)D and calcium, and regulation of tumor gene expression were examined. The combination treatments resulted in substantially greater inhibition of tumor growth than either agent alone. Soy diets alone caused a modest elevation in serum 1,25(OH)(2)D, whereas the calcitriol-soy combinations led to substantially elevated serum 1,25(OH)(2) D, hypercalcemia, and in some cases lethal toxicity. The combinations enhanced calcitriol activity in regulating target gene expression, including greater up-regulation of anti-proliferative (p21, IGFBP-3) and pro-apoptotic (Bax) genes, increased inhibition of anti-apoptotic (Bcl-2) and cell cycle promoting (cyclin D1) genes, and suppression of prostaglandin (PG) synthesis and signaling (COX-2, 15-PGDH, PG receptors). Increases in serum calcium were accompanied by elevated expression of intestinal calcium absorption genes (TRPV6, calbindin-9k). Soy increases the bioavailability of endogenous and administered calcitriol, thereby enhancing its anticancer effects and risk of hypercalcemia. Since both agents are easily available as dietary supplements, the increased potential for hypercalcemic toxicity becomes an important factor when considering the combined use of vitamin D and soy in PCa therapy.

Observation of Two Modes of Inhibition of Human Microsomal Prostaglandin E Synthase 1 by the Cyclopentenone 15-Deoxy-Δ12,14-prostaglandin J2

Microsomal prostaglandin E synthase 1 (MPGES1) is an enzyme that produces the pro-inflammatory molecule prostaglandin E(2) (PGE(2)). Effective inhibitors of MPGES1 are of considerable pharmacological interest for the selective control of pain, fever, and inflammation. The isoprostane, 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PGJ(2)), a naturally occurring degradation product of prostaglandin D(2), is known to have anti-inflammatory properties. In this paper, we demonstrate that 15d-PGJ(2) can inhibit MPGES1 by covalent modification of residue C59 and by noncovalent inhibition through binding at the substrate (PGH(2)) binding site. The mechanism of inhibition is dissected by analysis of the native enzyme and the MPGES1 C59A mutant in the presence of glutathione (GSH) and glutathione sulfonate. The location of inhibitor adduction and noncovalent binding was determined by triple mass spectrometry sequencing and with backbone amide H/D exchange mass spectrometry. The kinetics, regiochemistry, and stereochemistry of the spontaneous reaction of GSH with 15d-PGJ(2) were determined. The question of whether the anti-inflammatory properties of 15d-PGJ(2) are due to inhibition of MPGES1 is discussed.

Effect of lipopolysaccharide on the production of prostaglandin E2 and inhibition of uterine contractions by nitric oxide in pregnant inducible nitric oxide synthase knockout mice

The aim of the present study was to evaluate the effect of lipopolysaccharide (LPS) on the production of prostaglandin E2 (PGE2) and inhibition by nitric oxide (NO) of spontaneous contractions of uterine rings from pregnant inducible isoform of nitric oxide synthase knockout (iNOS KO) mice. iNOS KO and wild-type mice were sacrificed 6 h after intraperitoneal (i.p.) administration of LPS on day 14 of gestation. Uterine rings were equilibrated in Krebs-Henseleit solution for isometric tension recording. In part of the uterine rings, placental tissues were left attached. The bathing solution was analyzed for PGE2 by radioimmunoassay. Changes in spontaneous contractions in response to cumulative concentrations of L-arginine, diethylamine/nitric oxide (DEA/NO), and 8-bromo-cyclic guanosine monophosphate (8-br-cGMP) were determined. Treatment with LPS increased PGE2 production by uterine rings from wild-type and iNOS-KO mice. DEA/NO and 8-br-cGMP inhibited spontaneous contractions in uterine rings in the absence or presence of placenta, in both LPS-treated and LPS-untreated animals. LPS treatment attenuated maximal inhibition induced by the agents, both in the absence and presence of placental tissues in iNOS KO and wild-type mice. LPS induces PG production in mice myometrium that is not dependent on the integrity of iNOS, while LPS could induce pathophysiological iNOS obstruct uterine quiescence by physiological iNOS. Infection affects uterine contractile activity through PG production, as well as through placental and genetic factors. NO may be a double-edged sword in pregnant mice myometrium.

Ovarian Expression and Regulation of the Stromelysins During the Periovulatory Period in the Human and the Rat1

The matrix metalloproteinases (MMPs) are postulated to facilitate follicular rupture. In the present study, expression of the stromelysins (MMP3, MMP10, MMP11) was analyzed in the periovulatory human and rat ovary. Human granulosa and theca cells were collected from the dominant follicle at various times after human chorionic gonadotropin (hCG). Intact rat ovaries, granulosa cells, and residual tissue (tissue remaining after granulosa cell collection) were isolated from equine CG (eCG)-hCG-primed animals. Mmp10 mRNA was highly induced in human granulosa and theca cells and intact rat ovaries, granulosa cells, and residual tissue. Localization of MMP10 to granulosa and theca cells in both human and rat ovarian follicles was confirmed by immunohistochemistry. Mmp3 mRNA was unchanged in human cells and rat granulosa cells, but increased in intact rat ovaries and residual tissue. Mmp11 mRNA decreased following hCG treatment in human granulosa and theca cells as well as rat granulosa cells. Regulation of Mmp10 in cultured rat granulosa cells revealed that the EGF inhibitor AG1478 and the progesterone receptor antagonist RU486 suppressed the induction of Mmp10 mRNA, whereas the prostaglandin inhibitor NS398 had no effect. Studies on the Mmp10 promoter demonstrated that forskolin plus PMA stimulated promoter activity, which was dependent upon a proximal AP1 site. In conclusion, there are divergent patterns of stromelysin expression associated with ovulation, with a marked induction of Mmp10 mRNA and a decrease in Mmp11 mRNA, yet a species-dependent pattern on Mmp3 mRNA expression. The induction of Mmp10 expression suggests an important role for this MMP in the follicular changes associated with ovulation and subsequent luteinization.

Repeated application of glucocorticoids exacerbate pruritus via inhibition of prostaglandin D&lt;sub&gt;2&lt;/sub&gt; production of mast cells in a murine model of allergic contact dermatitis

Rebound is known to occur most typically when topical glucocorticoids are abruptly discontinued; however, its frequency and severity are poorly characterized. We previously created a novel murine model of topical glucocorticoid-induced pruritus; however, the mechanism underlying pruritus in this model has not been elucidated. Using this murine model, we aimed to determine the cause of augmentation of pruritus with a focus on the production of prostaglandin (PG) D(2). BALB/c mice with chronic allergic contact dermatitis induced by 5 weeks of repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) were treated topically with dexamethasone for 5 weeks immediately after the elicitation of dermatitis and after ear-swelling and scratching behavior were measured. RBL-2H3 mast cells were used to investigate the effect of dexamethasone on degranulation or PGD(2) production in IgE/antigen-stimulated mast cells. The scratching behavior induced by TNCB was augmented by topical application of dexamethasone, but dexamethasone did not have any effect on scratching bouts in mice that had not been treated with TNCB. Topical dexamethasone reduced the PGD(2) level, which increase in TNCB-treated mice, to the baseline level. Moreover, dexamethasone significantly decreased the PGD(2) production in IgE/antigen-stimulated RBL-2H3 mast cells; however, the same concentration of dexamethasone did not have any effect on the degranulation of stimulated mast cells. Topical glucocorticoids may exacerbate pruritus in a mouse model of allergic contact dermatitis via inhibition of PGD(2) production in antigen-mediated activated mast cells in the skin.