| ObjectiveEvaluate the dual regulating effects of gastrodin (Gas) on striatal extracellular DA concentration in Tourette’s syndrome (TS) rat models, and explore the underlying pharmacological mechanisms.MethodsA total of 70 male Wistar rats of 4 weeks old (weighing 100 ± 20g) were randomly assigned to control group (n=10) and TS model group (n=60). Rats in the control group were intraperitoneally injected (i.p.) with saline (0.9% sodium chloride) (5 ml/kg), and in the TS model group, two categories of groups were included:Apo group (n= 30) and IDPN group (n=30). The former was injected with Apomorphine (Apo) (2mg/kg, i.p.), while the latter was injected with 3,3’-Iminodipropionitrile (IDPN) (150 mg/kg, i.p.). Both Apo and IDPN groups were further divided into 3 groups (10 rats per group), and the related rats were treated respectively by oral gavage with saline at 10 ml/kg (Apo+ saline group and IDPN+ saline group), gastrodin at 20 mg/kg (Apo+ Gas group and IDPN+ Gas group), and Hal at 1.0 mg/kg (Apo+ Hal group and IDPN+ Hal group) once a day for 8 weeks. Based on the two TS models, the potential dual regulating effects of gastrodin on striatal extracellular DA content could be evaluated by intracerebral microdialysis and follow-up high-performance liquid chromatography with electrochemical detection (HPLC-ECD). In addition, on a weekly basis, we studied the alterations in the stereotyped abnormalities of the rats. And the correlated changes in DAT protein expression is further determined by western blot analysis to uncover the possible pharmacological mechanisms of the dual regulating effects of gastrodin on regulating extracellular DA level.Results1. Assessment of stereotyped behaviors.Repetitive measure analysis of variance showed that the ethological recording scores were significantly reduced for both groups (Apo:F2,27= 28.91,p< 0.01; IDPN: F2,27= 50.81, p< 0.01). Compared to the same saline-treated control rats, administration of either Apo or IDPN produced significant stereotyped behaviors in rats (Apo:p< 0.01; IDPN:p< 0.01). In the respectively treated groups exposed to Apo, the recording scores of stereotyped motor deficits in both Apo+Gas group and Apo+ Hal group decreased significantly as compared with the Apo+ saline group (Gas:p< 0.01; Hal:p< 0.01). In the IDPN-induced TS rats, we also observed a significant improvement in the stereotypic abnormalities after being treated by Gas and Hal respectively (Gas:p< 0.01; Hal:p< 0.01).2. Effects of gastrodin extracellular DA concentration in striatum.The ANOVA revealed a significant effect for both groups (Apo:F3,36= 5.68,p< 0.01; IDPN:F3;36= 51.84, p< 0.01). Two pharmacological manipulations, Apo and IDPN, produced completely opposite effects on extracellular level of DA:there was a significant increase in the striatal extracellular DA in the Apo+saline group (p< 0.01), while in the rats exposed to IDPN, the DA content was found to be decreased significantly (p< 0.01), both compared with the same control rats.The dual regulating effects of gastrodin on the extracellular DA content were detected during the study. First, gastrodin down-regulated the elevated extracellular DA content in Apo-induced rats towards a normal DA level. Second, it up-regulated the decreased striatal DA concentration in IDPN-induced rats towards a normal DA level. While in the Hal treated groups, no significant differences were found in the neurotransmitter after the treatment (Apo+Hal group vs Apo+saline group, p> 0.05; IDPN+Hal group vs IDPN+saline group,p> 0.05).3. Effects of gastrodin extracellular HVA concentration in striatumAt the end of the treatments, compared with the same control group, neither gastrodin nor Hal made any significant changes in extracellular level of HVA in Apo-induced rats. And in the rats exposed to IDPN, no significant differences were found in extracellular HVA content either, no matter they were treated by gastrodin or by Hal.4. Effects of gastrodin DAT protein expression in striatumThe ANOVA revealed a significant effect for groups (Apo:F3,36=10.92,p< 0.01; IDPN:F3,36= 21.15,p< 0.01). Both of the pharmacological manipulations, Apo and IDPN, significantly increased DAT protein expression in the striatum compared with the same control group (Apo:p< 0.01; IDPN:p< 0.01), and after being with gastrodin, there was a dramatic decrease in DAT protein expression in Apo+Gas group, while an opposite profile was showed in the rats exposed to IDPN. However, in the Hal treated groups, no significant differences were found in striatal DAT protein expressions after the treatment (Apo+ Hal group vs Apo+ saline group, p>0.05; IDPN+ Hal group vs IDPN+ saline group, p> 0.05).ConclusionBesides to make a significant improvement on stereotyped behavioral abnormalities of TS rats as Hal, gastrodin could regulate the extracellular DA concentration dually:it could make a gradually recovery in extracellular DA content from both up-regulated and down-regulated level. The chief mechanism would be the dual regulating effects of gastrodin on DAT protein expression, through which the released DA is reuptaken into nerve terminals. In summary, with this unique therapeutic value, gastrodin would be a potential therapeutic intervention for TS.ObjectiveEvaluate the dual regulating effects of Ningdong granule (NDG) on striatal dopamine (DA) content in Tourette’s syndrome (TS) rat models, and explore the underlying pharmacological mechanisms.MethodsSeventy male Wistar rats of 4 weeks old (weighing 100 ± 20g) were randomly assigned into control group (n= 10) and TS model group (n= 60). Rats in the control group received intraperitoneal infections of normal saline (0.9% sodium chloride) at a dose of 5 ml/kg/day, and in the TS model group, two kinds of groups were contained: Apo group (n= 30) and IDPN group (n= 30). The former was intraperitoneally injected with apomorphine (Apo) (2 mg/kg/day) while in the latter, the rats were injected with 3,3’-iminodipropionitrile (IDPN) (150 mg/kg/day). Both Apo and IDPN groups were further assigned to 3 groups (10 rats per group), and the associated rats received intragastric administration with saline at 10 ml/kg/day (Apo+ saline group and IDPN+ saline group), NDG at 370 mg/kg/day (Apo+ NDG group and IDPN+ NDG group), and Hal at 1.0 mg/kg/day (Apo+ Hal group and IDPN+ Hal group) respectively for 8 consecutive weeks. On a weekly basis, the rats were rated for locomotor and stereotyped behaviors by two independent blind observers. The potential dual values of NDG in reversing striatal DA content was examined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD), and correlated changes in DRD2 protein content were further determined by western blot analysis.Results1. Assessment of stereotyped behaviors.Using repeated measurements ANOVA, we found that both Apo and IDPN induced models had significant group effects (Apo:F2,27= 22.73,p< 0.01; IDPN: F2,27= 42.25, p<0.01), indicating vary degrees of differences among Apo and IDPN groups. Compared to the same control rats shared by Apo and IDPN groups throughout the study, both of the pharmacological manipulations, Apo and IDPN, were associated with marked behavior stereotypies in rats (Apo:p<0.01; IDPN:p< 0.01). After being treated, in the rats exposed to Apo, long-term administration of NDG as well as Hal effectively rescued the Apo-induced stereotyped motor deficits (NDG:p<0.01; Hal:p<0.01). Meanwhile, in the rats subjected to IDPN, a steady reduction in stereotypies was also observed in stereotypies compared to the IDPN+ saline group, after being treated by NDG and Hal respectively (NDG:p<0.01; Hal:p <0.01).2. Effects of NDG on striatal DA concentration.The ANOVA revealed significant effects for both groups (Apo:F3,36= 30.79,p< 0.01; IDPN:F3,36=16.07,p<0.01). Our data revealed that Apo and IDPN produced completely opposite effects on striatal DA content of the rats:manipulations of Apo significantly increased the DA concentration in striatum (p<0.01), while the IDPN exposures were associated with marked decrease in DA content (p<0.01), both compared with the same control rats.As tested by HPLC, we found that, long-term administrations of NDG significantly reduced the up-regulated striatal DA content in Apo-induced rats (Apo+ NDG group vs Apo+saline group p<0.01), and increased the down-regulated striatal DA content in IDPN-induced rats (IDPN+ NDG group vs IDPN+ saline group p< 0.01). In contrast, Hal failed to produce any modification of striatal DA alterations in either Apo-or IDPN-treated rats (Apo+ Hal group vs Apo+saline group, p> 0.05; IDPN+ Hal group vs IDPN+ saline group,p> 0.05).3. Effects of NDG on DRD2 protein content in striatum.The ANOVA revealed a significant effect for groups (Apo:F3,36= 24.69,p< 0.01 IDPN:F3;36=29.73, p<0.01). Apo and IDPN exposures were associated with significantly increased DRD2 protein content in the striatum compared with the same control group (Apo:p< 0.01; IDPN:p<0.01). After being treated, in the Apo groups, both NDG and Hal treatment prevented the Apo-induced elevation of DRD2 protein content in striatum (Apo+ NDG group vs Apo+ saline group p< 0.01; Apo+ Hal group vs Apo+ saline group p<0.01). Meanwhile, results similar to Apo groups were also observed in the IDPN groups after being treated with NDG and Hal respectively (IDPN+ NDG group vs IDPN+ saline group p< 0.01; IDPN+ Hal group vs IDPN+ saline group p< 0.01).ConclusionBesides to make a significant improvement on stereotyped behavioral abnormalities of TS rats as Hal, long-term administration of NDG could regulate the striatal dopamine alterations, either by increasing them after IDPN treatment or by decreasing them after Apo treatment. In summary, with this unique therapeutic value, gastrodin would be a potential therapeutic intervention for TS. |
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