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Nitric Oxide Synthase Expression in Glial Cells: Suppression by Tyrosine Kinase Inhibitors
Author(s) -
Feinstein Douglas L.,
Galea Elena,
Cermak Jennifer,
Chugh Punita,
Lyandvert Liubov,
Reis Donald J.
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.62020811.x
Subject(s) - nitric oxide synthase , tyrosine kinase , microbiology and biotechnology , chemistry , enzyme , biochemistry , biology , neuroscience , signal transduction
Rat brain glial cells have the capacity to express a calcium‐independent form of nitric oxide synthase (iNOS). To test if iNOS induction required tyrosine kinase activity, we made use of genistein, a selective inhibitor of tyrosine kinases. In both primary astrocyte cultures and C6 glioma cells, the presence of genistein prevented both lipopolysaccharide‐ and cytokine‐induced NOS activity in a dose‐dependent manner. The presence of tyrphostin‐25 (10 µ M ), which is highly specific for tyrosine kinases, also blocked iNOS induction. Additional characterization showed that genistein blocked iNOS induction in a dose‐dependent manner (IC 50 of ∼ 40 µ M ), that the continuous presence of genistein was not necessary to observe inhibition, and that preincubation with genistein led to higher levels of inhibition than the simultaneous addition of genistein and inducers. The decrease in iNOS activity due to genistein was accompanied by a decrease in iNOS mRNA level as detected by a specific PCR assay. These results indicate that induction of astroglial iNOS expression requires tyrosine kinase activity.