Nitric oxide, a new second messenger involved in the action of angiotensinII on neuronal differentiation of NG108-15 cells.

Nitric Oxide (NO) is a gas that diffuses freely through membranes of target cells to activate cGMP formation. NO is synthesised from arginine, by a fa mily of Nitric Oxide Synthase (NOS). In the brain, NO influences synaptic p lasticity, apoptosis and development. It has been recently shown that angio tensin II (Ang II) could mediate NO production by its two types of receptor s, AT(1) and AT(2). Since we have shown that Ang II, via the AT(2) receptor could induce neurite outgrowth and morphological differentiation of NG108- 15 cells, the aim of the study was to investigate if NO could be one of the second messengers involved in the Ang II effect. Using the Griess colorime tric assay, we found that Ang II, by its AT(2) receptor, induced nitrite fo rmation from NO. This effect was abolished by the N-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor. We also found that treatment of the cells with S-nitroso-N-acetylpenicillamine (SNAP), an exogenous source of NO, in duced the same morphological differentiation. These results demonstrate tha t the morphological differentiation induced by the AT(2) receptor is partly due to an increase in NO production.