Modulation of prostaglandin production by nitric oxide in astroglia

We examined the effects of exogenous nitric oxide (NO) on prostaglandin production in fetal ovine astroglia. Astroglia in secondary culture grown in 12 well plates were exposed to medium alone or medium containing 10 ng/ml interleukin 1 alpha (IL1 alpha), in the presence or absence of 10 and 100 microM sodium nitroprusside (SNP). Sodium nitroprusside is a NO donor. Prostaglandin F2 alpha (PGF2 alpha) levels were determined by enzyme immunoassay after 4 h of medium and/or drug application. Application of 100 microM SNP reduced basal levels of PGF2 alpha from 530 +/- 48 pg/ml (mean +/- SEM) (n = 9) to 248 +/- 60 pg/ml (n = 8) (P < 0.05). In IL1 alpha treated cells, PGF2 alpha levels were 846 +/- 109 pg/ml (n = 9) (P < 0.05, compared to basal levels) in the absence and 567 +/- 122 pg/ml (n = 9) in the presence of 100 microM SNP (P < 0.05, compared to IL1 alpha alone). We tested whether effects of exogenous NO on PGF2 alpha levels would be influenced by elimination of endogenously produced NO. Inhibition of NO synthase with 100 microM NG-nitro-L-arginine-methyl ester (L-NAME) did not affect PGF2 alpha levels during basal conditions, or affect reductions in PGF2 alpha levels during application of 100 microM SNP. In addition, L-NAME application did not affect IL1 alpha-induced increase in PGF2 alpha levels or reductions in PGF2 alpha levels with coapplication of 100 microM SNP. In contrast to the higher dose, application of 10 microM did not significantly affect PGF2 alpha levels. In summary, application of 100 microM SNP reduces basal production of PGF2 alpha and attenuates increases in PGF2 alpha levels with IL1 alpha application.