Measurement by in vivo brain dialysis of nitrite and nitrate levels as indices of nitric oxide production

Nitric oxide (NO) is a free radical gas with a role in signal transduction in diverse processes. In the central nervous system, NO acts as an intercellular signaling molecule as well as a neurotoxic substance. To clarify the role of NO in the brain, we measured nitrite and nitrate levels, as indices of NO production, in the dialysate of brains in conscious rats, by using an in vivo dialysis technique. We have demonstrated that NO production in the cerebellum can be modulated by the activation of glutamate receptors and KCl stimulation. Glial cells appear to be involved in the modulation of NO production by regulating the availability of an NO precursor, L-arginine. We have also demonstrated that NO plays a role in the development of lipopolysaccharide-induced brain dysfunction and pentylenetetrazol-induced kindling. We believe that the in vivo dialysis method to measure nitrite and nitrate levels as indices of NO production is a useful tool for investigating physiological and pathophysiological roles of NO in the brain.