Nitric oxide production from cultured spiral ligament fibrocytes: effects of corticosteroids.
CONCLUSIONS
This is the first report of nitric oxide (NO) production by cultured spiral ligament (SL) fibrocytes. The data suggest that dexamethasone (Dex) suppresses NO production by SL fibrocytes. Given that SL fibrocytes play a role in cochlear fluid and ion homeostasis, glucocorticoids may suppress cochlear malfunction caused by NO production in SL fibrocytes.


OBJECTIVE
To investigate NO production by cultured SL fibrocytes and regulation of NO production by Dex in mouse secondary cell cultures.


METHODS
Cultured SL fibrocytes were stimulated with tumor necrosis factor-alpha (TNF-alpha), and NO production was visualized with membrane-permeable 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM diacetate). Inducible nitric oxide synthase (NOSII) messenger RNA (mRNA) was measured by reverse transcription-polymerase chain reaction (RT-PCR).


RESULTS
After TNF-alpha stimulation, the fluorescence intensity increased in a time-dependent manner. This increase in fluorescence intensity was suppressed by a nonspecific NOS inhibitor, N(G)-nitro L-arginine methyl ester (L-NAME), and Dex. After TNF-alpha stimulation, expression of NOSII mRNA was observed. Expression of NOSII mRNA was inhibited by Dex.
Moriyama
Masaomi
M
Department of Otolaryngology, Faculty of Medicine, Oita University, Oita, Japan.
Yoshida
Kazuhide
K
Ichimiya
Issei
I
Suzuki
Masashi
M
D000818:Animals; D002478:Cells, Cultured; D003051:Cochlea / Q000166:cytology*; D003907:Dexamethasone / Q000494:pharmacology*; D005347:Fibroblasts / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D010521:Periosteum / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D005938:Glucocorticoids; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D019001:Nitric Oxide Synthase