| Title | mu-Opioid receptor-stimulated synthesis of reactive oxygen species (ROS) is mediated via phospholipase D2. | | Author(s) | Koch T, Seifert A, Wu DF, Rankovic M, Kraus J, Börner C, Brandenburg LO, Schröder H, Höllt V | | Institution | Department of Pharmacology and Toxicology, Otto-von-Guericke University, 39120 Magdeburg, Germany. | | Source | J Neurochem 2009 Jun 10. | | Abstract | We have recently shown that the activation of the rat mu-opioid receptor (MOPr, also termed MOR1) by the mu-agonist [D-Ala(2), Me Phe(4), Glyol(5)]enkephalin (DAMGO) led to an increase in phospholipase D2 (PLD2) activity and an induction of receptor endocytosis, whereas the agonist morphine, which does not induce opioid receptor endocytosis failed to activate PLD2. We report here that mu-opioid receptor-mediated activation of PLD2 stimulates production of reactive oxygen molecules via NADH/NADPH oxidase. Oxidative stress was measured with the fluorescent probe dichlorodihydrofluorescein diacetate (DCFDA) and the role of PLD2 was assessed by the PLD inhibitor D-erythro-sphingosine (sphinganine) and by PLD2-siRNA transfection. To determine whether NADH/NADPH oxidase contributes to opioid-induced production of reactive oxygen species, mu-agonist stimulated cells were pretreated with the flavoprotein inhibitor diphenylene iodonium (DPI) or the specific NADPH oxidase inhibitor apocynin. Our results demonstrate that receptor-internalizing agonists (like DAMGO, beta-endorphin, methadone, piritramide, fentanyl, sufentanil, and etonitazene) strongly induce NADH/NADPH-mediated ROS-synthesis via PLD-dependent signaling pathways, whereas agonists that do not induce mu-opioid receptor endocytosis and PLD2-activation (like morphine, buprenorphine, hydromorphone, and oxycodone) failed to activate ROS-synthesis in transfected HEK293 cells. These findings indicate that the agonist-selective PLD2-activation plays a key role in the regulation of NADH/NADPH-mediated ROS-formation by opioids. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19519662 |
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