Objective:To observe the behavioral effect on rats with parkinson disease treated by 50 mg/kg dose of L-dopa(L-dihydroxy-phenylalanine).Methods:The PD model rats were established through stereotaxic injection of 6-OHDA

and the successful models of PD were randomized into two groups:the PD control group and the LD model group

then the LD model group was treated intraperitoneally with 50 mg/kg dose of L-dopa for 8 weeks.Then at different time(2

4

6

8 weeks)

the behavioral changes of PD models(include the rotation behavior induced by APO

the initiating time of rotation

the lasting time of rotation

the maximum number of rotation

and the score of abnormal involuntary movement) were observed.Results:As the time given L-dopa went by ①the rotation behavior induced by APO gradually increased

and reached the peak at 6 weeks

compared with 2 weeks

there was difference(P<0.05);②the initiating time of rotation gradually decreased

but there was no difference(P>0.05);③the lasting time of rotation gradually increased

and 6

8 weeks compared with 2

4 weeks

there were significant difference(P<0.05);④the maximum number of rotation gradually increased

and 6 weeks compared with 2 weeks

there were difference(P<0.05);⑤the score of abnormal involuntary movement gradually increased

and 6

8 weeks compared with 2 weeks

there were difference(P<0.05 or P<0.01)

8 weeks compared with 4 weeks

there was also difference(P<0.05).Conclusion:The 50 mg/kg dose of levodopa has neurotoxic effect on rats with PD

the models display the typical and stable behavior

so it is suitable for the side-effect study of LD.