ucn-1028-c and Chronic-Disease

Repeated morphine treatment results in a decreased analgesic effect or the development of analgesic tolerance. However, we reported that some inflammatory chronic pain may inhibit morphine tolerance via kappa opioid receptor (KOR) activation. In this study, we further investigated the role of KOR in the inhibition of morphine tolerance in a chronic pain condition with a focus on the regulation of protein kinase C (PKC) activity.. Chronic pain was induced by formalin treatment into the dorsal part of the left hind paws of mice. The analgesic effect of morphine was measured by the tail flick method. We analysed the protein expression of PKC and its activity, and G-protein activity of mu opioid receptor (MOR) under repeated morphine treatment with or without formalin treatment.. We found that conventional subtypes of PKC (cPKC) were up-regulated by repeated morphine treatment. Also, antisense oligonucleotide (AS-ODN) targeting cPKC completely suppressed the development of morphine tolerance. The disappearance of the repeated morphine-induced up-regulation of cPKC was completely reversed by treatment with AS-ODN targeting KOR. In addition, AS-ODN targeting KOR significantly reversed the chronic pain-induced down-regulation of PKC activity or up-regulation of MOR [(35)S]GTPgammaS binding activity after repeated morphine treatment.. These results indicate that KOR plays an important role in the inhibition of repeated morphine-induced cPKC up-regulation under chronic pain condition. Furthermore, this may result in the increase of MOR activity and in the inhibition of morphine tolerance under chronic pain condition.

Topics: Analgesics, Opioid; Animals; Brain; Chronic Disease; Disease Models, Animal; Down-Regulation; Drug Tolerance; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enzyme Activation; Formaldehyde; Guanosine 5'-O-(3-Thiotriphosphate); Male; Mice; Morphine; Naphthalenes; Oligonucleotides, Antisense; Pain; Pain Measurement; Pain Threshold; Protein Kinase C; Protein Kinase Inhibitors; Receptors, Opioid, kappa; Receptors, Opioid, mu; Time Factors

We wished to determine whether the cytokine-inducible nitric oxide synthase (iNOS) pathway is modulated by chronic hypoxia in vitro.. We investigated the effects of the proinflammatory cytokine interleukin (IL)-1beta on expression of iNOS mRNA, iNOS protein, and NO production in cultured neonatal rat cardiomyocytes subjected to 1% O2 for 48 hours. Among several cytokines tested, IL-1beta was the most effective in stimulating NO production, which was maximum at 48 hours. In parallel, IL-1beta induced expression of both iNOS mRNA and protein. Hypoxia alone had no effect on NO production, iNOS gene expression, or protein induction. However, chronic hypoxia decreased IL-1beta-stimulated NO production, mRNA expression, and protein level in cardiac myocytes. Radioligand binding and electrophoretic mobility shift assays showed that during chronic hypoxia, IL-1 receptor density and activity of the transcription factor NF-kappaB induced by IL-1beta were decreased, which may account at least in part for the decrease in iNOS expression.. These data indicate that IL-1beta induces iNOS gene expression, de novo synthesis of iNOS protein, and NO generation in neonatal rat cardiomyocytes and that chronic hypoxia appears to be a potent negative regulator of iNOS expression in these cells.

Topics: Animals; Anti-Inflammatory Agents; Cells, Cultured; Chronic Disease; Dexamethasone; Enzyme Inhibitors; Gene Expression Regulation, Enzymologic; Genistein; Hypoxia; Interleukin 1 Receptor Antagonist Protein; Interleukin-1; Isoflavones; Muscle Fibers, Skeletal; Myocardium; Naphthalenes; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Rats; Rats, Sprague-Dawley; Receptors, Interleukin-1; RNA, Messenger; Sialoglycoproteins; Signal Transduction

Although phorbol esters, synthetic activators of protein kinase C (PKC), can stimulate large increases in the binding of cytosolic PKC to form membrane-bound PKC (PKCm, an indicator of PKC activation), the authors report that even small increases in PKCm induced by phorbol esters (8-12% of total PKC content) can be associated with significant PKC-mediated contractions in vitro (50-85% of maximum) in normal canine cerebral arteries. Increases in PKCm of similarly small magnitude were found in vitro when control artery segments were exposed to hemolysate, but only if the arterial smooth-muscle cells were first slightly depolarized by increased extracellular potassium to values of membrane potential similar to those observed in canine cerebral arteries during chronic cerebral vasospasm. These increases in PKCm (6-8% of total PKC content) coincided with a greatly augmented contractile response to hemolysate. These results show that the previous observation of only a small increase in PKCm (approximately 7% of total PKC content) after experimental subarachnoid hemorrhage in the canine model does not preclude a potentially important role for PKC-mediated contraction in the pathogenesis of cerebral vasospasm.

Topics: Animals; Cell Membrane; Cerebral Arteries; Chronic Disease; Cytosol; Dogs; Endothelin-1; Enzyme Activation; Enzyme Inhibitors; Hemolysis; Ischemic Attack, Transient; Membrane Potentials; Muscle, Smooth, Vascular; Naphthalenes; Phorbol 12,13-Dibutyrate; Phorbol Esters; Potassium; Protein Binding; Protein Kinase C; Stress, Mechanical; Subarachnoid Hemorrhage; Vasoconstriction; Vasoconstrictor Agents