Abstract
In this study, we evaluated the molecular mechanisms involved in morphine-induced macrophage apoptosis. Both morphine and TGF-beta promoted P38 mitogen-activated protein kinase (MAPK) phosphorylation, and this phosphorylation was inhibited by SB 202190 as well as by SB 203580. Anti-TGF-beta Ab as well as naltrexone (an opiate receptor antagonist) inhibited morphine-induced macrophage P38 MAPK phosphorylation. Anti-TGF-beta Ab also attenuated morphine-induced p53 as well as inducible NO synthase expression; in contrast, N(G)-nitro-L-arginine methyl ester, an inhibitor of NO synthase, inhibited morphine-induced P38 MAPK phosphorylation and Bax expression. Morphine also enhanced the expression of both Fas and Fas ligand (FasL), whereas anti-FasL Ab prevented morphine-induced macrophage apoptosis. Moreover, naltrexone inhibited morphine-induced FasL expression. In addition, macrophages either deficient in FasL or lacking p53 showed resistance to the effect of morphine. Inhibitors of both caspase-8 and caspase-9 partially prevented the apoptotic effect of morphine on macrophages. In addition, caspase-3 inhibitor prevented morphine-induced macrophage apoptosis. These findings suggest that morphine-induced macrophage apoptosis proceeds through opiate receptors via P38 MAPK phosphorylation. Both TGF-beta and inducible NO synthase play an important role in morphine-induced downstream signaling, which seems to activate proteins involved in both extrinsic (Fas and FasL) and intrinsic (p53 and Bax) cell death pathways.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Apoptosis / drug effects*
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Apoptosis / immunology
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Caspases / physiology
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Cell Line
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Cells, Cultured
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Enzyme Induction / drug effects
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Enzyme Induction / immunology
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Fas Ligand Protein
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Ligands
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MAP Kinase Signaling System / drug effects
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MAP Kinase Signaling System / immunology*
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Macrophages, Peritoneal / cytology
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Macrophages, Peritoneal / drug effects
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Macrophages, Peritoneal / enzymology*
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Macrophages, Peritoneal / immunology*
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Membrane Glycoproteins / biosynthesis
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Membrane Glycoproteins / metabolism*
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Membrane Glycoproteins / physiology
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Mice
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Mice, Inbred C3H
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Mice, Inbred C57BL
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Mice, Knockout
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / biosynthesis
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Mitogen-Activated Protein Kinases / metabolism*
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Mitogen-Activated Protein Kinases / physiology
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Morphine / pharmacology*
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Nitric Oxide Synthase / antagonists & inhibitors
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Nitric Oxide Synthase / biosynthesis
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Nitric Oxide Synthase / physiology
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Nitric Oxide Synthase Type II
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Phosphorylation / drug effects
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Proto-Oncogene Proteins / physiology
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Proto-Oncogene Proteins c-bcl-2*
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Receptors, Opioid / physiology
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Transforming Growth Factor beta / physiology
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bcl-2-Associated X Protein
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fas Receptor / biosynthesis
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fas Receptor / metabolism*
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fas Receptor / physiology
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p38 Mitogen-Activated Protein Kinases
Substances
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Bax protein, mouse
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Fas Ligand Protein
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Fasl protein, mouse
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Ligands
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Membrane Glycoproteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-bcl-2
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Receptors, Opioid
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Transforming Growth Factor beta
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bcl-2-Associated X Protein
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fas Receptor
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Morphine
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Nitric Oxide Synthase
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Nitric Oxide Synthase Type II
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Nos2 protein, mouse
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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Caspases