Effect of l-DOPA on nitric oxide production in striatum of freely mobile mice

Abstract

In Parkinson's disease, nitric oxide (NO) and other free radicals are thought to be involved in neuronal degeneration. Furthermore, l-DOPA is suggested to have a cytotoxic action on dopaminergic neurons. We studied 24-h NO production and the effect of l-DOPA on this in freely mobile mice using in vivo microdialysis. A microdialysis probe was implanted into the right striatum 12 h before the experiment. This dialysis probe was perfused with Ringer solution for 100 min, then with 20, 50, or 100 nM l-DOPA for 20 min, and finally with Ringer solution. Dialysate fractions were collected every 20 min for 4 h. Production of nitrite and total NO were significantly higher during daytime than during nighttime. Nitrate production was increased significantly by l-DOPA. NO production in the striatum appears to exhibit a diurnal rhythm and to increase with exposure to l-DOPA.