l-DOPA does not facilitate nitric oxide production in the rat striatum and substantia nigra: In vivo microdialysis study

Using in vivo microdialysis and flow-injection, we evaluated the production of nitric oxide (NO) in the striatum and substantia nigra of freely moving rats in response to challenge doses of l-dihydroxyphenylalanine ( l-DOPA) by measuring the NO metabolite levels of nitrate and nitrite. The dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) concentrations also were determined in the same perfusates. Intraperitoneal injection of l-DOPA produced a significant, dose-dependent increase in the extracellular levels of dopamine and DOPAC in these areas, but did not modify the extracellular levels of the NO metabolites. An acute dose of l-DOPA does not appear to facilitate NO production in the rat striatum and substantia nigra.