Induction of nitric oxide synthase in glial cells.
Primary astrocyte cultures, C6 glioma cells, and N18 neuroblastoma cells were assayed for nitric oxide synthase (NOS) activity with a bioassay of cyclic GMP production in RFL-6 fibroblasts. Treatment of astrocyte cultures for 16-18 h with lipopolysaccharide (LPS) induced NOS-like activity that was L-arginine and NADPH dependent, Ca2+ independent, and potentiated by superoxide dismutase. Induction was evident after 4 h, was dependent on the dose of LPS, and required protein synthesis. Treatment of astrocyte cultures with leucine methyl ester reduced microglial cell contamination from 7 to 1%, with a loss of 44% of NOS-like activity. C6 cells treated with LPS also showed Ca(2+)-independent and L-arginine-dependent NOS-like activity. N18 cells demonstrated constitutive Ca(2+)-dependent NOS-like activity that was not enhanced by LPS induction. These data indicate that NOS-like activity can be induced in microglia, astrocytes, and a related glioma cell line as it can in numerous other cell types, but not in neuron-like N18 cells.
Simmons
M L
ML
Department of Pharmacology, University of Iowa College of Medicine, Iowa City 52242.
Murphy
S
S
D000594:Amino Acid Oxidoreductases / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000201:enzymology; D006152:Cyclic GMP / Q000378:metabolism; D004790:Enzyme Induction; D008070:Lipopolysaccharides; D009457:Neuroglia / Q000201:enzymology*; D019001:Nitric Oxide Synthase; D012995:Solubility; D014407:Tumor Cells, Cultured
D008070:Lipopolysaccharides; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D006152:Cyclic GMP