Upregulation of neuronal nitric oxide synthase in in vitro stellate astrocytes and in vivo reactive astrocytes after electrically induced status epilepticus.
Neuronal nitric oxide synthase (nNOS) is a constitutively expressed and calcium-dependent enzyme. Despite predominantly expressed in neurons, nNOS has been also found in astrocytes, although at lower expression levels. We have studied the regulation of nNOS expression in cultured rat astrocytes from cortex and spinal cord by Western blotting and immunocytochemistry. nNOS was not detectable in cultured astrocytes grown in serum-containing medium (SCM), but was highly expressed after serum deprivation. Accordingly, calcium-dependent NOS activity and both intracellular nitrite levels and nitrotyrosine immunoreactivity after glutamate stimulation were higher in serum-deprived astrocytes than in cells grown in SCM. Serum deprivation induced a modification of astrocytes morphology, from flat to stellate. nNOS up-regulation was also observed in reactive astrocytes of rat hippocampi after electrically induced status epilepticus, as demonstrated by double-labeling experiments. Thus, nNOS upregulation occurs in both in vitro stellate and in vivo reactive astrocytes, suggesting a possible involvement of glial nNOS in neurological diseases characterized by reactive gliosis.
Catania
Maria Vincenza
MV
Institute of Neurological Sciences, National Research Council, section of Catania, vl. Regina Margherita 6, 95125 Catania, Italy. mcatania@area.ct.cnr.it
Giuffrida
Raffaella
R
Seminara
Giovanna
G
Barbagallo
Giuseppe
G
Aronica
Eleonora
E
Gorter
Jan A
JA
Dell'Albani
Paola
P
Ravagna
Agrippino
A
Calabrese
Vittorio
V
Giuffrida-Stella
Anna Maria
AM
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004558:Electric Stimulation; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000201:enzymology; D013226:Status Epilepticus / Q000201:enzymology* / Q000209:etiology; D015854:Up-Regulation
D016895:Culture Media, Serum-Free; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D002118:Calcium