Abstract: Objective: To verify and evaluate the protective function of KYNA on the SNc dopaminergic cell bodies and fibres,which is microinjected thirty minutes prior to 6-OHDA. Methods: A total 40 adult female SD rats in 4groups (each of the 4groups consisting of 10 rats).GroupA,B,C,D received,respectively,a unilateral microinjection of normal saline,KYNA, KYNA+6-OHDA or 6-OHDA,into the left ventral tegmental area(VTA) and SNc.T wo weeks later,the changes of tyrosine hydroxylase-positive neurons in SNc and dopaminergic fiber in VTA were investigated in immunocytochemical methods. Data were reported as X S.Statistical significance levels were calculated by using Analysis of Variance and Rank Test. Results: In the third day after injection,the ethologic observation was performed following motivation by apomorphine. Group A and B have no symptom.Group C was significantly improved than group D.The number of T H-positive cells in group A,B,C significantly increase in comparison with the group D (P<0.01).Application of KYNA prior to 6-OHDA produced a significant increase of T H-positive fiberic density than group D around the injection sites in VTA. Conclusion: These data indicate that the early application of Glu receptor antagonist KYNA may decrease neurotoxic damage of 6-OHDA on nigral DA neurons.