Glutaminergic tonic action potentiate MPP+-induced hydroxyl radical production in rat striatum

摘要

The effect of glycine on 1-methyl-4-phenylpyridinium ion (MPP+)-induced hydroxyl radical ((OH)-O-center dot) formation in the extracellular fluid of rat striatum were investigated. Rats were anesthetized and sodium salicylate in Ringer's solution (0.5 nmol/mu l/min) was infused through a microdialysis probe to detect the generation of (OH)-O-center dot as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (2,3-DHBA) in rat striatum. MPP+ (5 mmol/L) produced an increase in (OH)-O-center dot formation. When glycine (1 mmol/L) was infused into the rat striatum through a microdialysis probe after MPP+ treatment, the marked in the level of 2,3-DHBA was observed in the brain dialysate. However, in the presence of MK-801 (100 mu mola), a non competitive antagonist of N-methyl-Daspartate (NMDA), glycine failed to increase the 2,3-D-HBA formation by MPP+. When corresponding experiments were performed with nitro-L arginine (L-NNA) (1 mmol/L), a nitric oxide synthase (NOS) inhibitor, same result was obtained. These results suggest that MPP+-induced (OH)-O-center dot generation may modulated by glycine via NMDA receptor in rat striatum. This increase might be explained because of the presence of a glutaminergic tonic action