An increase in intracellular cyclic AMP modulates nitric oxide production in IFN-gamma-treated macrophages.
Macrophages treated with IFN-gamma alone are stimulated to produce nitric oxide. The level of nitric oxide production can be enhanced significantly when IFN-gamma treatment is combined with other agents (e.g., LPS, TNF-alpha, IL-2, etc.). We tested the hypothesis that cAMP plays a role in the IFN-gamma-induced activation of macrophages. Our experiments indicate that factors that increase the concentration of cAMP in the murine macrophage cell line ANA-1 can also enhance IFN-gamma-induced production of nitric oxide. PGE2 and cholera toxin increased the production of nitrite (an indicator of nitric oxide production) in IFN-gamma-treated ANA-1 macrophages by at least twofold. These factors produced no increase in nitric oxide production in the absence of IFN-gamma treatment. The increase in nitric oxide production corresponded to an increase in the accumulation of nitric oxide synthase mRNA without a change in stability of mRNA. Dibutyryl cAMP and Sp-cAMPs (a selective activator of cAMP-dependent protein kinase I and II) also increased nitric oxide production in IFN-gamma-treated macrophages. However, at very high concentrations (i.e., >100 microM), the stimulatory effect was decreased. These studies indicate that elevation of intracellular cAMP causes a dose-dependent, biphasic alteration of IFN-gamma-induced nitric oxide production in murine macrophages. Moreover, they suggest that agents that affect nitric oxide synthesis may do so via modulation of the cAMP second messenger system.
Mullet
D
D
Department of Pharmacology, Ohio State University College of Medicine, Columbus 43210, USA.
Fertel
R H
RH
Kniss
D
D
Cox
G W
GW
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000494:pharmacology / Q000502:physiology*; D015232:Dinoprostone / Q000494:pharmacology; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000187:drug effects; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D013873:Thionucleotides / Q000494:pharmacology
D004791:Enzyme Inhibitors; D016328:NF-kappa B; D012333:RNA, Messenger; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D009569:Nitric Oxide; D003994:Bucladesine; D007371:Interferon-gamma; D002772:Cholera Toxin; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D015232:Dinoprostone