m&b-28-767 and butaprost

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

Although the role of PGE2 in maintaining ductus arteriosus (DA) patency is well established, the specific PGE2 receptor subtype(s) (EP) involved have not been clearly identified. We used late gestation fetal and neonatal lambs to study developmental regulation of EP receptors. In the fetal DA, radioligand binding and RT-PCR assays virtually failed to detect EP1 but detected EP2, EP3D, and EP4 receptors in equivalent proportions. In the newborn lamb, DA total density was one-third of that found in the fetus and only EP2 was detected. Stimulation of EP2 and EP4 increased cAMP formation and was associated with DA relaxation. Though stimulation of EP3 inhibited cAMP formation, it surprisingly relaxed the fetal DA both in vitro and in vivo. This EP3-induced relaxation was specifically diminished by the ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide. In conclusion, PGE2 dilates the late gestation fetal DA through pathways that involve either cAMP (EP2 and EP4) or K(ATP) channels (EP3). The loss of EP3 and EP4 receptors in the newborn DA is consistent with its decreased responsiveness to PGE2.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Adenosine Triphosphate; Alprostadil; Animals; Animals, Newborn; Anti-Arrhythmia Agents; Anti-Ulcer Agents; Binding, Competitive; Biphenyl Compounds; Colforsin; Dinoprost; Ductus Arteriosus; Female; Fetus; Polymerase Chain Reaction; Potassium Channels; Pregnancy; Prostaglandin Antagonists; Prostaglandins E, Synthetic; Radioligand Assay; Receptors, Prostaglandin E; Sheep; Tritium; Vasoconstriction; Xanthenes; Xanthones

High glucose reportedly stimulates prostaglandin (PG) E2 production and DNA synthesis in mesangial cells (MCs). However, the pathophysiological significance of PGE2 in MCs has remained unclear.. The effects of prostanoids on [3H]-thymidine uptake and cAMP production in rat MCs cultured with 5.6 mM glucose, 25 mM glucose, or 5.6 mM glucose supplemented with 19.4 mM mannitol were examined. The gene expression of PGE2 receptor (EP) subtypes in MCs was analyzed with Northern blotting techniques.. Northern blotting indicated EP1 and EP4 gene expression in MCs. EP1 agonists and PGE2 stimulated [3H]-thymidine uptake in MCs. EP1 antagonists dose dependently attenuated high-glucose-induced [3H]-thymidine uptake, which suggests EP1 involvement, by an increase in intracellular Ca2+, in DNA synthesis of MCs. On the other hand, forskolin, db-cAMP, and 11-deoxy-PGE1, an EP4/EP3/EP2 agonist, significantly decreased DNA synthesis in MCs. These inhibitory effects are thought to be mediated via EP4 as a result of an increase in cAMP synthesis. The effects via EP4 seem to be particularly important because PGE2-induced cAMP synthesis was significantly attenuated in the high-glucose group compared with the mannitol group, in which [3H]-thymidine uptake did not increase in spite of augmented PGE2 production.. The increase in DNA synthesis in MCs under high-glucose conditions can be explained, at least in part, by the high-glucose-induced inhibition of cAMP production via EP4, which augments EP1 function in conjunction with the overproduction of PGE2.

Topics: 1-Methyl-3-isobutylxanthine; Alprostadil; Animals; Anti-Ulcer Agents; Blotting, Northern; Calcium; Cells, Cultured; Colforsin; Cyclic AMP; Dinoprostone; Gene Expression; Glomerular Mesangium; Glucose; Male; Menstruation-Inducing Agents; Phosphodiesterase Inhibitors; Prostaglandins E, Synthetic; Rats; Rats, Inbred WKY; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP1 Subtype; RNA, Messenger; Thymidine; Tritium

Prostaglandin (PG)E2 has both a vasodilating action and a protective function in the gastric mucosa. There are four subtypes of PGE2-sensitive, or EP, receptors.. To identify the subtype of EP receptors in the microvessels of the rat gastric mucosa using EP2 and EP3 receptor agonists.. The posterior wall of the anaesthetized rat stomach was secured in a chamber and superfused with Tyrode's solution, and the gastric microcirculation of the mucosal base was observed through a window with transillumination. PGE2 and its derivatives (20 microL) were applied topically in the window.. PGE2 (0.001-10 micromol/L), misoprostol (EP2/EP3 receptor agonist; 0.01-100 micromol/L) and butaprost (EP2 receptor agonist; 1-1000 micromol/L) dilated the arterioles dose-dependently, but M&B 28 767 (EP3 receptor agonist; 0.001-10 micromol/L) did not alter their diameters. M&B 28 767 constricted the venules and collecting venules dose-dependently whereas butaprost dilated them. PGE2 and misoprostol had bell-shaped dose-response curves: constriction by low doses of PGE2 and misoprostol (0.001-0.1 micromol/L and 0.01-1 micromol/L) and dilation by high doses of PGE2 and misoprostol (0.1-100 micromol/L and 1-100 micromol/L).. These results suggest that PGE2 dilated both arterioles and venules in the rat gastric mucosa through the EP2 receptors and constricted the venules through the EP3 receptors.

Topics: Alprostadil; Analysis of Variance; Animals; Dinoprostone; Gastric Mucosa; Male; Microcirculation; Misoprostol; Rats; Rats, Sprague-Dawley; Receptors, Prostaglandin E; Vasoconstriction; Vasodilation

The expression by T lymphocytes (T cells) of more than one of the functionally distinct subtypes of prostaglandin E2 (PGE2) receptors (Rs), designated EP1, EP2, EP3, and EP4 Rs, is a principal determinant of specificity and diversity of the immune effects of PGE2. The cultured line of human leukemic T cells, termed HSB.2, co-expresses a total of 7282 +/- 1805 EP3, EP4, and EP2 Rs per cell with a Kd of 3.7 +/- 1.4 nM (mean +/- S.E., n = 9). The EP3/EP1 R-selective agonist sulprostone, EP3/EP2/EP4 R-selective agonists M&B 28767 and misoprostol, and EP2 R-selective agonist butaprost but not the EP1 R-selective antagonist SC-19220 competitively inhibited the binding of [3H]PGE2 to HSB.2 cells. Stimulation of increases in the intracellular concentration of cyclic AMP ([cAMP]i) by PGE2, misoprostol, and butaprost and of increases in the intracellular concentration of calcium ([Ca2+]i) by PGE2 and sulprostone demonstrated the respective involvement of EP2/EP4 Rs and EP3 Rs in transduction of biochemical signals. Matrix metalloproteinase (MMP)-9 was identified by zymography and Western blots as the principal MMP secreted by HSB.2 cells. The cytosolic level and secretion of MMP-9 were increased maximally after 24 h of incubation of HSB.2 cells with 10(-8)-10(-6) M PGE2, sulprostone, M&B 28767, and misoprostol but not with 10(-6) M PGF2alpha, PGD2, PGI2, or butaprost, suggesting a principal dependence on EP3 Rs. That stimulation of MMP-9 secretion by PGE2 was not diminished in Ca2+-free medium but was suppressed significantly and dose-dependently by thapsigargin, an inhibitor of endomembrane Ca2+-ATPase, suggested that MMP-9 expression by HSB.2 cells is mediated by increases in [Ca2+]i attributable to release of Ca2+ from intracellular stores. The lack of effect of dibutyryl cAMP, forskolin, and SQ 22536, an adenylyl cyclase inhibitor, on MMP-9 secretion by HSB.2 cells argued against any role for cAMP-dependent mechanisms linked to EP2/EP4 Rs. Cycloheximide and actinomycin D, which respectively inhibited protein and RNA synthesis, suppressed basal and PGE2 induction of MMP-9 production by HSB.2 cells. Northern analysis indicated that PGE2 and sulprostone time-dependently increased expression of MMP-9 mRNA. Thus, stimulation of MMP-9 in HSB.2 T cells by PGE2 is attributable to [Ca2+]i-dependent EP3 R-mediation of increases in message transcription.

Topics: Adenine; Alprostadil; Blotting, Northern; Bucladesine; Calcium; Cell Line; Colforsin; Collagenases; Cyclic AMP; Cycloheximide; Dactinomycin; Dinoprostone; Enzyme Inhibitors; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Kinetics; Leukemia, T-Cell; Matrix Metalloproteinase 9; Misoprostol; Prostaglandins E, Synthetic; Receptors, Prostaglandin E; RNA, Messenger; T-Lymphocytes; Thapsigargin; Transcription, Genetic; Tumor Cells, Cultured

To determine what types of prostanoid receptors are involved in the central effect of prostaglandin E2 (PGE2) on nociception, we administered PGE2 and its agonists, i.e., 17-phenyl-omega-trinor PGE2 (an EP1 receptor agonist), butaprost (an EP2 receptor agonist), 11-deoxy PGE1 (an EP2/EP3 receptor agonist, EP2 >> EP3) and M&B28767 (an EP3 receptor agonist) into the lateral cerebroventricle (LCV) of rats and observed the changes of paw-withdrawal latency on a hot plate. The LCV injection of PGE2 (10 pg/kg-10 ng/kg), 11-deoxy PGE1 (100 pg/kg-10 ng/kg) and M&B28767 (1 pg/kg-100 pg/kg) produced a significant reduction in the paw-withdrawal latency. The maximal reduction was observed 15 min after the LCV injection of these drugs. Neither 17-phenyl-omega-trinor PGE2 (1 pg/kg-1 microgram/kg) nor butaprost (1 pg/kg-100 microgram/kg) induced any significant changes in the paw-withdrawal latency. The LCV injection of PGE2 (1 microgram/kg) and 17-phenyl-omega-trinor PGE2 (50 micrograms/kg) increased the latency only 5 min after LCV injection. These findings indicate that the LCV injection of PGE2 induces thermal hyperalgesia through EP3 receptors and analgesia through EP1 receptors by its central action in rats.

Topics: Alprostadil; Animals; Dinoprostone; Hot Temperature; Hyperalgesia; Injections, Intraventricular; Male; Pain; Prostaglandins E, Synthetic; Rats; Rats, Wistar; Receptors, Prostaglandin E

Prostaglandin E2 augments bradykinin-induced discharges of polymodal receptors as studied in vitro preparations. The antagonist and agonists for three subtypes of EP receptors were used to determine which subtype is involved in this phenomenon. The agonist for EP3 (M&B28767) simulated the PGE2-induced effect but not for EP2 (butaprost). The antagonist for EP1 (AH6809) did not suppress the effect. These findings indicate the involvement of the EP3 receptor subtype in the effect.

Topics: Alprostadil; Animals; Bradykinin; Dinoprostone; Dogs; Dose-Response Relationship, Drug; Drug Synergism; Epididymis; Hot Temperature; In Vitro Techniques; Male; Nociceptors; Physical Stimulation; Prostaglandin Antagonists; Receptors, Prostaglandin E; Testis; Xanthenes; Xanthones

Topics: Alprostadil; Animals; Bradykinin; Capillary Permeability; Dinoprostone; Drug Synergism; Inflammation; Rabbits; Receptors, Prostaglandin; Receptors, Prostaglandin E; Skin; Vasodilation