u-0126 and adenosine-3--5--cyclic-phosphorothioate

Prostaglandin E(2) (PGE(2)) is a bioactive prostanoid implicated in the inflammatory processes of acute lung injury/acute respiratory distress syndrome. This study investigated whether PGE(2) can induce production of interleukin (IL)-8, the major chemokine for neutrophil activation, from human pulmonary microvascular endothelial cells (HPMVECs). PGE(2) significantly enhanced IL-8 protein production with increases in IL-8 mRNA expression and intracellular cAMP levels. HPMVECs expressed only EP4 receptor mRNA. The PGE(2) effects were mimicked by a selective EP4 receptor agonist, ONO-AE1-329, and inhibited by a selective EP4 receptor antagonist, ONO-AE3-208, or a protein kinase A inhibitor, Rp-adenosine 3',5'-cyclic monophosphorothioate triethylamine salt. The specific agonist for EP1, EP2, or EP3 receptor did not induce IL-8 production. PGE(2)-induced IL-8 production was accompanied by p38 phosphorylation and was significantly inhibited by a p38 inhibitor, SB-203580, but not by an ERK1/2 inhibitor, U-0126, or a JNK inhibitor, SP-600125. Additionally, PGE(2) increased cyclooxygenase-2 expression with no change in constitutive cyclooxygenase-1 expression, suggesting possible involvement of an autocrine or paracrine manner. In conclusion, PGE(2) enhances IL-8 production via EP4 receptor coupled to G(s) protein in HPMVECs. Activation of the cAMP/protein kinase A pathway, followed by p38 activation, is essential for these mechanisms. Because neutrophils play a critical role in the inflammation of acute lung injury/acute respiratory distress syndrome, IL-8 released from the pulmonary microvasculature in response to PGE(2) may contribute to pathophysiology of this disease.

Topics: Acute Lung Injury; Anthracenes; Butadienes; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Endothelial Cells; Humans; Imidazoles; Interleukin-8; JNK Mitogen-Activated Protein Kinases; Lung; MAP Kinase Signaling System; Methyl Ethers; Microvessels; Naphthalenes; Neutrophils; Nitriles; p38 Mitogen-Activated Protein Kinases; Phenylbutyrates; Pyridines; Receptors, Prostaglandin E, EP4 Subtype; Respiratory Distress Syndrome; RNA, Messenger; Thionucleotides

The laterocapsular division of the central nucleus of the amygdala (CeLC) has emerged as an important site of pain-related plasticity and pain modulation. Glutamate and neuropeptide receptors in the CeLC contribute to synaptic and behavioral changes in the arthritis pain model, but the intracellular signaling pathways remain to be determined. This study addressed the role of PKA, PKC, and ERK in the CeLC. Adult male Sprague-Dawley rats were used in all experiments. Whole-cell patch-clamp recordings of CeLC neurons were made in brain slices from normal rats and from rats with a kaolin/carrageenan-induced monoarthritis in the knee (6 h postinduction). Membrane-permeable inhibitors of PKA (KT5720, 1 microM; cAMPS-Rp, 10 microM) and ERK (U0126, 1 microM) activation inhibited synaptic plasticity in slices from arthritic rats but had no effect on normal transmission in control slices. A PKC inhibitor (GF109203x, 1 microM) and an inactive structural analogue of U0126 (U0124, 1 microM) had no effect. The NMDA receptor-mediated synaptic component was inhibited by KT5720 or U0126; their combined application had additive effects. U0126 did not inhibit synaptic facilitation by forskolin-induced PKA-activation. Administration of KT5720 (100 microM, concentration in microdialysis probe) or U0126 (100 microM) into the CeLC, but not striatum (placement control), inhibited audible and ultrasonic vocalizations and spinal reflexes of arthritic rats but had no effect in normal animals. GF109203x (100 microM) and U0124 (100 microM) did not affect pain behavior. The data suggest that in the amygdala PKA and ERK, but not PKC, contribute to pain-related synaptic facilitation and behavior by increasing NMDA receptor function through independent signaling pathways.

Topics: Amygdala; Animals; Arthritis; Behavior; Butadienes; Carbazoles; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Indoles; Male; Maleimides; Neuronal Plasticity; Neurons; Nitriles; Pain; Protein Kinase C; Protein Kinase Inhibitors; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Synaptic Transmission; Thionucleotides

1. The aims of the present study were to determine whether delta-opioid receptor stimulation enhanced proliferation of and to investigate the role of the extracellular signal-regulated kinase (ERK) pathway in ventricular myocytes from neonatal rats. 2. At concentratins ranging from 10 nmol/L to 10 micromol/L, [D-Ala2,D-Leu5]enkephalin (DADLE) concentration-dependently promoted myocardial growth and DNA synthesis and altered the cytoskeleton. 3. At 1 micromol/L, DADLE also increased the expression and phosphorylation of ERK. 4. These effects of 1 micromol/L DADLE were abolished by 10 micromol/L naltrindole, a selective delta-opioid receptor antagonist, 10 nmol/L U0126, a selective ERK antagonist, 1 micromol/L staurosporine, an inhibitor of protein kinase (PK) C, and 100 micromol/L Rp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt hydrate (Rp-cAMPS), an inhibitor of PKA. 5. In conclusion, delta-opioid receptor stimulation enhances the proliferation and development of the ventricular myocytes of neonatal rats. The ERK pathway and related signalling mechanisms, namely PKC and PKA, are involved.

Topics: Analgesics, Opioid; Animals; Animals, Newborn; Butadienes; Cell Proliferation; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cytoskeleton; Dose-Response Relationship, Drug; Enkephalin, Leucine-2-Alanine; Extracellular Signal-Regulated MAP Kinases; Heart Ventricles; Myocytes, Cardiac; Naltrexone; Narcotic Antagonists; Nitriles; Phosphorylation; Protein Kinase C; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Receptors, Opioid, delta; Signal Transduction; Staurosporine; Thionucleotides; Time Factors