losartan-potassium and diphenyleneiodonium

Occurrence of macrophage apoptosis has been implicated for the altered immune function found in an opiate milieu. In the present study, we evaluated the role of oxidative stress in morphine-induced macrophage apoptosis. Morphine promoted the apoptosis of macrophages. This effect of morphine was associated with the production of superoxide and nitric oxide (NO). Antioxidants provided protection against morphine-induced macrophage injury. In addition, diphenyleneiodonium chloride, an inhibitor of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, attenuated the proapoptotic effect of morphine. Antitransforming growth factor-beta (anti-TGF-beta) antibody and propranolol (an inhibitor of the phospholipase D pathway) inhibited morphine-induced superoxide generation as well as apoptosis. N'-Tetraacetic acid tetra (acetoxymethyl) ester, a calcium-chelating agent, inhibited morphine-induced apoptosis, whereas thapsigargin (a calcium agonist) stimulated macrophage apoptosis under basal as well as morphine-stimulated states. These studies suggest that morphine-induced macrophage apoptosis is mediated through downstream signaling involving TGF-beta and NO production. Moreover, there is NADPH oxidation activation involving phospholipase D and Ca(2+), leading to the generation of superoxide. In in vivo studies, administration of N-acetyl cysteine and preinduction of heme oxygenase activity and epoetin alpha prevented morphine-induced peritoneal macrophage apoptosis, thus further confirming the role of oxidative stress in morphine-induced macrophage apoptosis.

Topics: Animals; Anti-Anxiety Agents; Antioxidants; Apoptosis; Calcium; Enzyme Activation; Enzyme Inhibitors; Epoetin Alfa; Erythropoietin; Heme Oxygenase (Decyclizing); Macrophages, Peritoneal; Mice; Morphine; NADPH Oxidases; Narcotics; Nitric Oxide; Onium Compounds; Oxidative Stress; Phospholipase D; Propranolol; Recombinant Proteins; Superoxides; Thapsigargin; Transforming Growth Factor beta

Treatment of human hepatoma cells (HepG2) with NO-donors for 24 h inhibited hypoxia-induced erythropoietin (EPO) gene activation. NO was found to increase the production of reactive oxygen species (ROS), the putative signaling molecules between a cellular O2-sensor and hypoxia inducible factor 1 (HIF-1). HIF-1 is the prime regulator of O2-dependent genes such as EPO. NO-treatment for more than 20 h reduced HIF-1-driven reporter gene activity. In contrast, immediately after the addition of NO, ROS levels in HepG2 cells decreased below control values for as long as 4 h. Corresponding to these lowered ROS-levels, HIF-1 reporter gene activity and EPO gene expression transiently increased but were reduced when ROS levels rose thereafter. Our findings of a bimodal effect of NO on ROS production shed new light on the involvement of ROS in the mechanism of O2-sensing and may explain earlier conflicting data about the effect of NO on O2-dependent gene expression.

Topics: Acridines; Anaerobiosis; Carcinoma, Hepatocellular; DNA-Binding Proteins; Erythropoietin; Gene Expression Regulation, Neoplastic; Genes, Reporter; Humans; Hydrogen Peroxide; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; NADH, NADPH Oxidoreductases; NADPH Oxidases; Nitric Oxide; Nitric Oxide Donors; Nitrogen Oxides; Nuclear Proteins; Onium Compounds; Oxygen; Penicillamine; Reactive Oxygen Species; RNA, Messenger; Signal Transduction; Spermine; Transcription Factors; Transcriptional Activation; Transfection; Tumor Cells, Cultured