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The effect of nitric oxide on cytokine‐induced release of PGE 2 by human cultured astroglial cells
Author(s) -
Mollace Vincenzo,
Colasanti Marco,
Muscoli Carolina,
Lauro Giuliana M,
Ian Michelangelo,
Rotiroti Domenicantonio,
Nistico' Giuseppe
Publication year - 1998
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701852
Subject(s) - sodium nitroprusside , cytokine , nitric oxide , prostaglandin e , nitric oxide synthase , chemistry , tumor necrosis factor alpha , prostaglandin e2 , endocrinology , medicine , biochemistry , biology , immunology
The role of the L ‐arginine‐nitric oxide (NO) pathway on the formation of prostaglandin E 2 (PGE 2 ) by human cultured astroglial cells incubated with interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) was investigated. Incubation of T 67 astroglial cell line with IL‐β (10 ng ml −1 ) and TNF‐α (500 u ml −1 ) produced a significant ( P <0.05) increase of both nitrite (the breakdown product of NO), cyclic GMP and PGE 2 levels in cell supernatants. N ω ‐nitro‐ L ‐arginine methyl ester ( L ‐NAME; 20–300 μ M ), an inhibitor of NO synthase (NOS), inhibited the increase of cyclic GMP and nitrite levels found in supernatants of cytokine‐treated astroglial cells and reduced the release of PGE 2 . The latter effect showed that the enhanced arachidonic acid (AA) metabolism subsequent to stimulation of astroglial cells with IL‐1β and TNF‐α was, at least in part, induced by NO. This occurred also when sodium nitroprusside (SNP; 120 μ M ), an NO donor, was incubated with astroglial cells, an effect antagonized by oxyhaemoglobin (OxyHb; 10 μ M ). The inhibition elicited by L ‐NAME on PGE 2 ‐release by cytokine‐treated astroglial cells was reversed by adding AA (40 μ M ), showing that the effect of NO on cytokine‐dependent PGE 2 release occurred at the cyclo‐oxygenase (COX) level. Furthermore, the release of PGE 2 in cytokine‐treated astroglial cells was inhibited by indomethacin (10 μ M ), a COX inhibitor as well as by preincubating cells with dexamethasone (20 μ M ), an inhibitor of inducible enzymes, showing that the inducible isoform of COX (COX‐2) was involved. On the other hand, pretreating astroglial cells with methylene blue (MB; 10 μ M ), an inhibitor of NO biological activity acting at the guanylate cyclase level, failed to affect PGE 2 release in cytokine‐treated astroglial cells, leading to the conclusion that cyclic GMP changes related to NO formation are not involved in the generation of AA metabolites. The present experiments demonstrated that the release of PGE 2 by astroglial cells pretreated with IL‐1β and TNF‐α is due to enhanced COX‐2 activity via activation of the L ‐arginine‐NO pathway, and this may be relevant to the understanding of the pathophysiological mechanisms underlying neuroimmune disorders.