OBJECTIVE:Ningdong granule is a traditional Chinese medicine preparation for the treatment of Tourette’s syndrome.METHODS:Sixty-four rats were randomly assigned to a control group and three experimental groups,respectively.Rat models of Tourette’s syndrome were established via intraperitoneal injection of apomorphine(Apo).The rats in the experimental groups were subsequently intragastrically injected with haloperidol at 10 mg/kg(haloperidol group),Ningdong granule at 370 mg/kg(NDG group),and normal saline(0.9%) at 10 mL/kg(Apo group),respectively.Rat behaviors were observed and recorded on a daily basis.After 12 w,all rats were sacrificed,and sera and striatal tissues were harvested.Homovanillic acid levels in sera,as well as dopamine and dopamine D2 receptor mRNA expression in the striatum,were measured to determine possible mechanisms of Ningdong granule on the dopamine system in a rat model of Tourette’s syndrome.RESULTS:Following intervention,stereotype actions of the Tourette’s syndrome rats were significantly inhibited in the haloperidol and NDG groups,respectively(P<0.01).Homovanillic levels were significantly greater in the haloperidol and NDG groups,respectively(P<0.05).In addition,dopamine levels were significantly less in the NDG group(P<0.01),and DRD2 mRNA expression was significantly reduced in the haloperidol and NDG groups,respectively(P<0.05).CONCLUSION:Results demonstrated that Ningdong granule effectively inhibited stereotype actions and Tourette’s syndrome symptoms by promoting dopamine metabolism,reducing dopamine levels in the striatum,increasing homovanillic acid content in sera,and reducing mRNA expression of DRD2 in the striatum. OBJECTIVE: Ningdong granule is a traditional Chinese medicine preparation for the treatment of Tourette’s syndrome. METHODS: Sixty-four rats were randomly assigned to a control group and three experimental groups, respectively. Rat models of Tourette’s syndrome were established via intraperitoneal injection of apomorphine ( Apo). The rats in the experimental groups were intragastrically injected with haloperidol at 10 mg / kg haloperidol group, Ningdong granule at 370 mg / kg (NDG group), and normal saline (0.9%) at 10 mL / kg Apo group), respectively.Rat behaviors were observed and recorded on a daily basis. After 12 w, all rats were sacrificed, and sera and striatal tissues were harvested. Humovanillic acid levels in sera, as well as dopamine and dopamine D2 receptor mRNA expression in the striatum, were measured to determine possible mechanisms of Ningdong granule on the dopamine system in a rat model of Tourette’s syndrome .RESULTS: Following intervention, stereotype actions of the Tourette’s sy ndrome rats were significantly inhibited in the haloperidol and NDG groups, respectively (P <0.01) .Homovanillic levels were significantly greater in the haloperidol and NDG groups, respectively (P <0.05) .In addition, dopamine levels were significantly less in the NDG group (P <0.01), and DRD2 mRNA expression was significantly reduced in the haloperidol and NDG groups, respectively (P <0.05). CONCLUSION: Results of that Ningxiang granule effectively regulated stereotype actions and Tourette’s syndrome symptoms by promoting dopamine metabolism, reducing dopamine levels in the striatum, increasing homovanillic acid content in sera, and reducing mRNA expression of DRD2 in the striatum.