Department of Biology, University of Rome Tor Vergata, Italy.
The role of the L-arginine-NO pathway on the formation of PGE2 by cultured astroglial cells incubated with the HIV coating glycoprotein gp120 was investigated. Preincubation of human cultured T 67 astrocytoma cells with gp 120 (100-500 nM) produced a significant increase of nitrite (the breakdown product of NO) and PGE2 in cell supernatants. The effect of gp 120 on both nitrite and PGE2 production was antagonized by inhibition of NO synthase by L-NAME (20-300 microM). The inhibition of gp120-induced PGE2 production by L-NAME was reverted by addition of arachidonic acid (30 microM), an effect antagonized by the cyclo-oxygenase inhibitor indomethacin (10 microM). Methylen bleu, an inhibitor of the biological activity of NO acting at the guanylate cyclase level failed to affect gp 120-mediated PGE2 release showing that the increase of cGMP subsequent to NO production was not involved in the modulatory activity of NO on arachidonic acid cascade. On the basis of present experiments we conclude that gp-120-induced release of PGE2 by astroglial cells is driven by NO, thereby contributing in the involvement of glial cells in HIV-related cerebral disorders.