m&b-28-767 and sulprostone

We examined the mechanism of the inhibitory effect of prostanoid EP(3) receptor agonists on naloxone-precipitated withdrawal syndrome in morphine-dependent rats. Rats were rendered morphine dependent by subcutaneous (s.c.) implantation of two pellets containing 75 mg morphine for 5 days. Morphine withdrawal syndrome was precipitated by i.p. injection of naloxone (3 mg/kg). Intracerebroventricular (i.c.v.) administration of (+/-)-15alpha-hydroxy-9-oxo-16-phenoxy-17,18, 19,20-tetranorprost-13-trans-enoic acid (M&B28,767: prostanoid EP(3) receptor agonist) or sulprostone (prostanoid EP(1)/EP(3) receptor agonist) significantly suppressed many withdrawal signs. Northern blotting and in situ hybridization studies revealed that i.c.v. administration of M&B28,767 (1 pg/rat) attenuated the elevation of c-fos mRNA during naloxone-precipitated withdrawal in many brain regions, including the cerebral cortex, thalamus, hypothalamus and locus coeruleus. Double in situ hybridization analysis revealed that in the locus coeruleus most of the tyrosine hydroxylase mRNA-positive neurons expressed mu-opioid receptor mRNA and more than half of these neurons were positive for prostanoid EP(3) receptor mRNA. These results indicate that the suppression by prostanoid EP(3) receptor agonists of naloxone-precipitated morphine withdrawal syndrome can be attributed to the inhibition of neuronal activity in several brain regions, including the locus coeruleus, the largest source of central noradrenergic neurons.

Topics: Alprostadil; Animals; Brain; Dinoprostone; Dose-Response Relationship, Drug; Gene Expression Regulation; In Situ Hybridization; Injections, Intraventricular; Locus Coeruleus; Male; Morphine; Morphine Dependence; Naloxone; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Receptors, Opioid, mu; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP3 Subtype; RNA, Messenger; Substance Withdrawal Syndrome; Tyrosine 3-Monooxygenase

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

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

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