Objective To investigate the possible mechanism of Guiling Pa’ an Pills（ 龟羚帕安丸） combined with transplantation of neural stem cells（ NSCs） for the treatment of Parkinson’s disease（ PD）. Methods PD rat models were established by intraperitoneal injection of 6-OHDA. Rats were randomly divided into blank control group

transplantation control group

metoprolol group

and Guiling Pa’ an Pills high

middle

low dose group

with 10 in each group. Giving 5 μl of PBS to the blank control group and 5 μl of NSCs suspension to the other groups

and 5 μl of NSCs suspension to the other groups. At the same time

the low

middle and high dose groups were given Guiling Pa’an Pills 0. 9

1. 8

and 3. 6 g/（ kg·d） by gavage respectively

and metoprolol group was given metoprolol solution 50 mg/（ kg·d） gavage. The transplantation control group and the blank control group were given intragastric administration of an equal volume of saline. Two times a day for 4 weeks. After the rats were transplanted（ 0 week） and after 4 weeks of gavage

the number of rotations in each group was counted and the number of rotations（ K value） was calculated. The serum 5-hydroxytryptamine（ 5-HT）

dopamine（ DA）

norepinephrine（ NE） content in each group was measured at the 4 th week after intragastric administration. Results In the blank control group

the number of rotations at 4 weeks and K value were significantly higher than that of the other groups（ P < 0. 01）. In Chinese herbs groups

the number of rotations of the rats at the 4 th week and K value were significantly lower than the metoprolol group（ P < 0. 05 or P < 0. 01）. The rotation number of the middle dose group was lower than the high dose group of the Chinese herb at the 4 th week

and the K value was lower than the low and high dose Chinese herbs groups（ P <0. 01）. Compared with the blank control group

serum levels of 5-HT

DA

and NE in the other groups were significantly higher（ P < 0. 01）. Serum 5-HT

DA and NE levels in the middle and low dose groups of Chinese medicine were significantly higher than those in the metoprolol group（ P < 0. 01）; serum 5-HT

DA

and NE levels in the middle dose group were higher than those in the low and high dose groups of the Chinese medicine（ P < 0. 05 or P <0. 01）. Conclusion Guiling Pa’an Pills can significantly improve the behavioral symptoms of PD rats. The mechanism may be related to the increase of serum 5-HT

DA and NE levels. The middle dose has best efficacy.