title: Morphine enhances interleukin-12 and the production of other pro-inflammatory cytokines in mouse peritoneal macrophages.
abstract: In this study we investigated the capacity of morphine to modulate expression of cytokines in peritoneal macrophages. Mice were implanted subcutaneously with a 75-mg morphine slow-release pellet, and 48 h later resident peritoneal macrophages were harvested. Control groups received placebo pellets, naltrexone pellets, or morphine plus naltrexone pellets. Adherent cells were stimulated with lipopolysaccharide (LPS: 10 microg/mL) plus interferon-gamma (IFN-gamma: 100 units/mL) to induce cytokine production. After 24 h RNA was extracted for analysis of cytokine mRNA levels by reverse transcriptase-polymerase chain reaction, or supernatants were collected after 48 h for determination of cytokine production by enzyme-linked immunosorbent assay (ELISA). Morphine enhanced mRNA expression of interleukin (IL)-12 p40 and tumor necrosis factor alpha (TNF-alpha) compared with controls, whereas IL-10 levels were unchanged by drug treatment. ELISA data showed that both IL-12 p40 and p70 were increased by morphine. The enhancement of IL-12 at both the mRNA and protein levels was antagonized by naltrexone, indicating that the modulation of this cytokine by morphine is via a classic opioid receptor. These results are particularly interesting in light of our previous observation that 48 h after morphine pellet implantation, the peritoneal cavity is colonized with gram-negative and other enteric bacteria. The enhancement of IL-12 by morphine might be related to morphine-induced sepsis.
authors.affiliation: Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
authors.forename: X
authors.initials: X
authors.lastname: Peng
authors.forename: D M
authors.initials: DM
authors.lastname: Mosser
authors.forename: M W
authors.initials: MW
authors.lastname: Adler
authors.forename: T J
authors.initials: TJ
authors.lastname: Rogers
authors.forename: J J
authors.initials: JJ
authors.lastname: Meissler
authors.forename: T K
authors.initials: TK
authors.lastname: Eisenstein
mesh_terms: D000276:Adjuvants, Immunologic / Q000096:biosynthesis / Q000235:genetics; D000701:Analgesics, Opioid / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D003352:Corynebacterium; D003692:Delayed-Action Preparations; D005260:Female; D018836:Inflammation Mediators; D007371:Interferon-gamma / Q000494:pharmacology; D016753:Interleukin-10 / Q000096:biosynthesis / Q000235:genetics; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013268:Stimulation, Chemical; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000276:Adjuvants, Immunologic; D000701:Analgesics, Opioid; D003692:Delayed-Action Preparations; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D009292:Narcotic Antagonists; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12; D009271:Naltrexone; D009020:Morphine; D007371:Interferon-gamma