Expression of citrulline–nitric oxide cycle in lipopolysaccharide and cytokine-stimulated rat astroglioma C6 cells

Regulation of Nitric Oxide Production by Arginine Metabolic Enzymes

“…Coinduction of iNOS and AS has also been shown in activated human tumor cell lines (12) and rat glioma C6 cells (13,14). NO is produced from citrulline as well as from arginine in activated C6 cells, indicating that the citrulline-NO cycle is actually functioning (14). When rat astrogliarich cultures were treated with LPS and IFN-␥, AS was induced and colocalization of AS and iNOS was shown in microglial cells (15).…”

“…AL was also coinduced in vivo (11). Coinduction of iNOS and AS has also been shown in activated human tumor cell lines (12) and rat glioma C6 cells (13,14). NO is produced from citrulline as well as from arginine in activated C6 cells, indicating that the citrulline-NO cycle is actually functioning (14).…”

Coinduction of Nitric Oxide Synthase and Arginine Metabolic Enzymes in Endotoxin-induced Uveitis Rats

“…This may suggest that AS is the rate-limiting step of arginine recycling and that basal level of AL is suf®cient for this recycling. In fact, AS is highly induced in many other tissues and cells after immunostimulation, but AL is not or only weakly induced (Hattori et al, 1994;Nussler et al, 1994;Flodstro Èm et al, 1995;Nagasaki et al, 1996;Zhang et al, 1999Zhang et al, , 2000Kawahara et al, 2001). Immunohistochemical analysis revealed that induced AS is colocalized with iNOS in most of the in®ltrating in¯ammatory cells in LPS-injected eyes.…”

“…However, arginase II immunoreactivity was negative in these cells. cells (Zhang et al, 1999(Zhang et al, , 2000. Arginine concentration in rat aqueous humor (64 mM) is about one half of that in plasma (125 mM; Reddy, 1967).…”

“…Arginase II is expressed in kidney, small intestine and lactating mammary gland, and at lower levels in other tissues Vockley et al, 1996). AS (and also AL in some cases) is coinduced with iNOS in activated macrophages (Nussler et al, 1994;Nagasaki et al, 1996), vascular endothelial cells (Hattori et al, 1994), pancreatic b-cells (Flodstro Èm et al, 1995), glioma C6 cells (Zhang et al, 1999), microglial MG5 cells (Kawahara et al, 2001) and neuronal PC12 cells (Zhang et al, 2000), and upregulates NO synthesis. On the other hand, arginase I and/or II are also induced in activated macrophages and downregulate NO production (Sonoki et al, 1997;Louis et al, 1998;Morris et al, 1998;Salimuddin et al, 1999).…”