16-16-dimethylprostaglandin-e2 and butaprost

Mice deficient in the G-protein alpha subunit G(i)alpha(2) spontaneously develop colitis and colon cancer. IL-11 is a pleiotropic cytokine known to protect the intestinal epithelium from injury in animal models of colitis and is produced by subepithelial myofibroblasts in response to inflammatory mediators including TGF-beta, IL-1beta, and PGE(2). Arachidonic acid release and subsequent PGE(2) production is significantly decreased in the colonic mucosa of G(i)alpha(2)-/- mice, and we hypothesized that this would affect mucosal IL-11 production. Mucosal levels of IL-11 were found to be significantly decreased in G(i)alpha(2)-/- mice despite the presence of mild colitis. Primary cultures of G(i)alpha(2)-/- intestinal and colonic myofibroblasts (IMF and CMF, respectively) produced less basal and TGF-beta or IL-1beta-stimulated IL-11 mRNA and protein than wild-type cells. Inhibitors of ERK or p38 MAPK activation dose dependently inhibited IMF and CMF IL-11 production in response to TGF-beta stimulation, whereas 16,16 dimethyl-PGE(2) and prostanoid receptor subtype-selective agonists induced IL-11 production. Treatment of animals with the EP4-specific agonist ONO-AE1-329 resulted in enhanced mucosal levels of IL-11, and increased IL-11 production by ex vivo cultured CMF. Modulation of cAMP levels produced diverging results, with enhancement of TGF-beta-induced IL-11 release in IMF pretreated with 8-Br-cAMP and inhibition in cells treated either with pertussis toxin or the PKA inhibitor H-89. These data suggest a physiological role for prostaglandins, MAPK signaling, and cAMP signaling for the production of myofibroblast-derived IL-11 in the mouse intestinal mucosa.

Topics: 16,16-Dimethylprostaglandin E2; Alprostadil; Animals; Cells, Cultured; Colon; Cyclic AMP; Dinoprostone; Dose-Response Relationship, Drug; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Flavonoids; GTP-Binding Protein alpha Subunit, Gi2; Imidazoles; Interleukin-11; Interleukin-1beta; Intestine, Small; Methyl Ethers; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Protein Kinase Inhibitors; Pyridines; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP4 Subtype; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta

In the preterm newborn, a patent ductus arteriosus is in large part a result of the increased sensitivity of the immature ductus to prostaglandin E2 (PGE2). PGE2 acts through 3 G protein-coupled receptors (EP2, EP3, and EP4) that activate both adenyl cyclase and K(ATP) channels. We explored these pathways to identify the mechanisms responsible for the increased sensitivity of the immature ductus to PGE2.. We measured EP receptor content (mRNA and protein), receptor binding, cAMP production, and isometric tension in rings of ductus taken from immature (65% gestation) and mature (95% gestation) sheep and baboon fetuses. Ductus relaxation and cAMP generation were augmented in response to selective EP receptor agonists in the immature ductus. 8-Br-cAMP, a stable cAMP analogue, produced greater relaxation in the immature ductus. In the presence of a selective protein kinase A inhibitor, Rp-8-CPT cAMPS, the developmental differences in sensitivity to PGE2 could no longer be demonstrated. EP2, EP3, and EP4 receptor densities were higher in immature ductus, despite similar receptor mRNA and protein contents at the 2 gestational ages. In contrast, forskolin and NaF, direct activators of adenyl cyclase and Gs, respectively, elicited comparable increases in cAMP in both age groups. KATP channel inhibition also had similar effects on PGE2-induced relaxation in both age groups.. Two mechanisms explain the increased sensitivity of the immature ductus to PGE2: (1) increased cAMP production because of increased binding of PGE2 to the individual EP receptors and (2) increased potency of cAMP on protein kinase A-regulated pathways.

Topics: 16,16-Dimethylprostaglandin E2; 8-Bromo Cyclic Adenosine Monophosphate; Adenosine; Adenylyl Cyclases; Alprostadil; Animals; Biphenyl Compounds; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Dinoprostone; Ductus Arteriosus; Enzyme Activation; Female; Gestational Age; Glyburide; Indomethacin; Isometric Contraction; NG-Nitroarginine Methyl Ester; Nitroprusside; Papio; Potassium Channels; Pregnancy; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP2 Subtype; Receptors, Prostaglandin E, EP3 Subtype; Receptors, Prostaglandin E, EP4 Subtype; Sheep; Signal Transduction; Sodium Fluoride; Thionucleotides; Vasomotor System

Prostaglandin E(2) (PGE(2)) exerts mainly luteotrophic effects in the corpus luteum. In other tissues, PGE(2) acts via specific PGE(2) receptor subtypes including EP1, which modulates intracellular calcium ([Ca(2+)](i)) and EP2, which is coupled to cyclic AMP (cAMP) generation. We have therefore investigated the presence of functional EP1 and EP2 receptors using human granulosa-lutein (GL) cells. Reverse-transcription PCR revealed that GL cells expressed mRNA transcripts encoding both EP1 and EP2 receptors. When GL cells were challenged with ligands that can bind to both receptor subtypes (PGE(2) and 16,16 dimethyl PGE(2)) or exclusively to EP2 (butaprost), both cAMP formation and progesterone synthesis were stimulated. Furthermore, the cAMP response to these agonists could be significantly blocked by an EP1/2 antagonist AH6809 but not by an EP1-selective antagonist SC19220. Exposure of GL cells to 16,16-dm PGE(2) transiently raised [Ca(2+)](i) levels, which could be prevented by both AH6809 and SC19220. We therefore conclude that human GL cells express functional EP1 and EP2 receptors.

Topics: 16,16-Dimethylprostaglandin E2; Alprostadil; Calcium; Cells, Cultured; Cyclic AMP; Dibenz(b,f)(1,4)oxazepine-10(11H)-carboxylic acid, 8-chloro-, 2-acetylhydrazide; Dinoprostone; Dose-Response Relationship, Drug; Female; Granulosa Cells; Humans; Intracellular Fluid; Lutein; Progesterone; Prostaglandin Antagonists; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP1 Subtype; Receptors, Prostaglandin E, EP2 Subtype; RNA, Messenger; Xanthenes; Xanthones

A fourth PGE receptor subtype, the EP4 receptor, has recently been described in the pig saphenous vein (PSV). Similar to the EP2 receptor, it mediates relaxation and is linked to stimulation of adenylate cyclase. The aim of this study was to determine whether or not the EP receptor present in the rabbit jugular vein (RJV), currently classified as an atypical EP2 receptor, is of the EP4 subtype. The relaxant activities of four EP2 agonists, 11-deoxy PGE1, 16,16-dimethyl PGE2, butaprost, and AH 13205, on the RJV and PSV have been examined, and the effect of the EP4 receptor antagonist AH 23,848B studied. The EP2 agonists showed a similar order of potency on the two preparations. 11-Deoxy PGE1 and 16,16-dimethyl PGE2 were potent agonists on the EP4 receptors of the PSV and on the RJV giving approximately equi-effective concentration ratios (EECs) of 2.0-6.6 and 2.8-9.9, respectively, compared to PGE2 (EEC = 1), and so do not discriminate between EP2 and EP4 receptors. Butaprost was less active on these preparations (EEC 42-43) than on classical EP2 receptors, and AH 13205 was much less active (EEC 3100-2780). While these results suggest that the EP receptors on the RJV are of the EP4 subtype, this was not confirmed using the EP4 receptors antagonist AH 23,848B.

Topics: 16,16-Dimethylprostaglandin E2; Alprostadil; Animals; Biphenyl Compounds; Endothelium, Vascular; Jugular Veins; Male; Muscle Relaxation; Muscle, Smooth, Vascular; Prostaglandins F, Synthetic; Prostanoic Acids; Rabbits; Receptors, Prostaglandin E; Saphenous Vein; Swine