Effect of sphingosine on rat glial cells: inhibition of prostaglandin E2 and insensitivity of nitric oxide generation.
The effect of sphingosine on lipopolysaccharide (LPS)-mediated protein kinase C (PKC) activation and prostaglandin E2 (PGE2) and nitric oxide (NO) production was studied in primary cultures of rat glial cells. Incubation of cells with LPS elicited translocation of PKC from the cytosolic to the membranous compartment, as shown by measuring PKC activity and by immunoblotting. Under these conditions, a sustained increase in both PGE2 and NO production was measured. Thus, PGE2 levels were 259 +/- 28 (n = 8) and 230 +/- 48 (n = 4) (control levels 11.4 +/- 5.2 (n = 5) and 13 +/- 7.5 (n = 3)) pg/ml, at 24 and 48 h, respectively. NO levels were 9.3 +/- 0.9 (n = 10) and 11.6 +/- 0.8 (n = 9) (control levels 0.4 +/- 0.18 and 1.0 +/- 0.44) nmol/ml, at 24 and 48 h, respectively. Sphingosine, a naturally occurring compound, which inhibits PKC activity, elicited a concentration-dependent decrease in LPS-mediated PGE2 production. This inhibition was more pronounced after 48 h than after 24 h of incubation (IC50 = 8 and 20 microg sphingosine, respectively). By contrast, sphingosine did not inhibit NO production under the same conditions. We conclude that sphingosine may be involved in modulation of the local inflammatory response in glial cells, at least in part. We also surmise that LPS-mediated PGE2 production and NO production are probably regulated by different mechanisms, i.e., a PKC-dependent and a PKC-independent mechanism.
Boneh
A
A
Department of Paediatrics, Hadassah University Hospitals and Hebrew University Hadassah Medical School, Jerusalem, Israel.
Hochman-Meyuchas
R
R
Sicsic
C
C
Brenner
T
T
D000818:Animals; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005333:Fetus / Q000166:cytology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D013110:Sphingosine / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009569:Nitric Oxide; D011493:Protein Kinase C; D015232:Dinoprostone; D013110:Sphingosine