Recovery by NO of the iron-attenuated dopamine dynamics in nigrostriatal system of rat brain

In vivo electrochemical detection was employed to study the chronic effect of nitric oxide on iron-induced alterations in dopamine dynamics, including K+-evoked dopamine overflows and the clearance of exogenous dopamine in ra t striatum. Intranigral infusion of fresh S-nitroso-N-acetylpenicillamine ( SNAP), a nitric oxide donor, did not alter either dopamine dynamics in the striatum or the lipid peroxidation in substantia nigra 7 days after the inf usion, indicating that nitric oxide is not neurodestructive. By contrast, i nfusion of iron in substantia nigra chronically degenerated the nigrostrita l dopaminergic system. Co-infusion of iron fresh SNAP, prevented the iron-i nduced reductions in K+-evoked dopamine overflows. Furthermore, the clearan ce of exogenous dopamine was attenuated in the striatum ipsilateral to the substantia nigra infused with iron. An improvement by fresh SNAP of iron-in duced reduction in dopamine clearance was observed in rats co-infused with fresh SNAP and iron mixture compared to iron-lesioned group. Taken together , our in vivo electrochemical study suggests that nitric oxide does not alt er dopamine dynamics in nigrostriatal dopaminergic system. Rather, nitric o xide appears to protect dopamine dynamics from iron-induced oxidative stres s in rat brain. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.