ABSTRACT
Objective To investigate the effect of neutral amino acid on preventing Parkinson disease.Methods Mice were injected with L-Valine,L-Pheylalanine,D-Valine or L-Lysine before or after paraquat administration,by which prakinsonian mouse model was constructed.The paraquat immunoreactivity was observed within nigral cell bodies.Then neurodegeneration and ?-synuclein aggregation were observed by immunohistochemistry and Western blot.Results Paraquat immunoreactivity was abolished by the administration of L-Valine,L-Pheylalanine before paraquat exposure.Pre-treatment with these two amino acids also protected the paraquat-induced loss of nigrostriatal dopaminergic cells and formation of thioflavine S-positive aggregates.In contrast, paraquat-induced toxicity was unaffected if animals were injected with these two amino acids after paraquat exposure or pre-treated with D-Valine or L-Lysine.Conclusions L-type neutral amino acids such as L Valine and L-Pheylalanine can prevent paraquat-induced neurodegeneration and a synuclein pathology through a competitive inhibition mechanism with stereospecificity in the central nervous system (CNS).Neutral amino acid could protect the dopaminergic neuron in substantia nigra and may prevent Parkinson disease.