还原型谷胱甘肽对帕金森病保护性治疗的实验研究

目的观察还原型谷胱甘肽对帕金森病(PD)大鼠模型的保护性治疗作用,并探讨其作用机理.方法应用6-羟基多巴制作PD大鼠模型.将大鼠模型随机分为4组(每组8只):模型组,谷胱甘肽(GSH)组,左旋多巴(Ldopa)组,谷胱甘肽 左旋多巴组,另设对照组(8只),分别给予相应处理,共45天,给药前后均进行行为学测试,给药结束后行免疫组化和电镜观察,并测定黑质区谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)、活性氧(ROS)及线粒体呼吸链酶复合体Ⅰ水平.结果 (1)GSH对其旋转行为无明显影响(P＞0.05);(2)GSH 能减轻黑质区氧化应激损伤;(3)GSH能增强黑质呼吸链酶复合体Ⅰ活性;(4)免疫组化发现GSH组TH-IR神经元较模型组明显增多(P＜0.001);(5)电镜下发现GSH可部分延缓凋亡进程.结论 (1)GSH能减轻黑质区氧化应激损伤,并对线粒体呼吸链具有一定保护作用;(2)GSH与L-dopa合用既可有效改善症状,又对残存黑质多巴胺能神经元具有保护性治疗作用.     

还原型谷胱甘肽对黑质多巴胺能细胞保护作用的实验研究

目的　观察还原型谷胱甘肽 (GSH)对帕金森病 (PD)大鼠模型的保护性治疗作用 ,并探讨其作用机制。方法　应用 6 羟基多巴制作PD大鼠模型 ,随机分为 4组 :模型组 ,GSH组 ,左旋多巴 (L dopa)组 ,GSH并L dopa组 ,并设正常组 ,给药结束后行电镜观察 ,并测定各组其余大鼠黑质区谷胱甘肽过氧化物酶 (GSH Px)、丙二醛 (MDA)、活性氧 (ROS)及线粒体呼吸链酶复合体Ⅰ水平 ,测定尾状核头部多巴胺 (DA)、高香草酸 (HVA)及单胺氧化酶 B(MAO B)水平。结果　①GSH组旋转行为无明显变化 ,但GSH并L dopa组可使大鼠旋转行为明显改善 ;②GSH能减轻黑质区氧化应激损伤 ;③GSH能增强黑质呼吸链酶复合体Ⅰ活性 ;④GSH组对MAO B活性及DA、HVA含量和DA/HVA比值均无明显影响 ;⑤电镜下发现模型组存在大量中、晚期凋亡细胞 ,而GSH组以早、中期凋亡为主。结论　①GSH能减轻PD模型大鼠黑质区氧化应激损伤 ,并对线粒体呼吸链具有一定保护作用 ;②GSH与L dopa合用 ,既可有效改善症状 ,又对残存DA能神经元具有保护性治疗作用。     

还原型谷胱甘肽对左旋多巴毒性拮抗作用的实验研究

目的 :观察还原型谷胱甘肽 (GSH)对左旋多巴 (L dopa)毒性的拮抗作用。方法 :将实验动物分为 4组 (每组 8只 ) :治疗组 ,阴性对照组 ,阳性对照组 ,正常鼠组。比较给药前后的行为学变化 ,给药后测定各组大鼠黑质区GSH Px、MDA、ROS及线粒体呼吸链酶复合体Ⅰ水平。结果 :L dopa能加重黑质区氧化应激损伤 ,降低呼吸链酶复合体Ⅰ活性 ,GSH与其合用可部分拮抗上述作用。结论 :GSH能部分拮抗L dopa的毒性作用 ,对PD模型大鼠具有一定的细胞保护作用     

左旋多巴对帕金森病大鼠毒性作用的实验研究

目的　研究左旋多巴 (L dopa)对帕金森病 (PD)模型大鼠异常行为、黑质抗氧化系统、线粒体呼吸链功能和神经递质代谢的影响及其机制。方法　应用 6 羟基多巴胺 (6 OHDA)立体定向注射制作PD大鼠模型 ,给PD大鼠L dopa 2 5mg/ (kg·d)灌胃 ,共 4 5d。给药前后分别进行行为学测试 ,给药后测定黑质区谷胱甘肽过氧化物酶 (GSH Px)、丙二醛 (MDA)、活性氧 (ROS)及线粒体呼吸链酶复合体Ⅰ水平 ,测定尾状核头部多巴胺 (DA)、高香草酸 (HVA)、单胺氧化酶 B(MAO B)的水平。结果　 (1)L dopa组大鼠旋转速度给药前为(13.1± 1.5 )r/min ,给药后为 (7.2± 1.6 )r/min,给药前后比较差异有显著性 (P <0 .0 1) ;(2 )L dopa组GSH Px活性、呼吸链酶复合体Ⅰ水平降低 ,MDA含量、ROS活性升高 ,与对照组比较差异均有显著性 (均P <0 .0 1) ;(3)L dopa组MAO B活性、DA、HVA含量及DA/HVA比值与对照组比较均显著升高 (P <0 .0 5～ 0 .0 1)。结论L dopa能有效改善PD大鼠的旋转行为 ,但可加重黑质区氧化应激损伤 ,抑制线粒体呼吸链酶活性。     

还原型谷胱甘肽合用粉防己碱对帕金森病大鼠抗氧化效应的研究

目的:观察还原型谷胱甘肽合用粉防己碱(Tet)对帕金森病(PD)大鼠抗氧化效应的影响。方法:应用定向注射6-羟基多巴胺法制作(PD)大鼠模型,将成功模型分4组给予不同药物50d,观察大鼠旋转行为,测定黑质谷胱甘肽(GSH)和纹状体丙二醛、活性氧水平。结果:GSH合用Tet能:①显著改善模型大鼠旋转行为;②减轻氧化应激损伤,纹状体丙二醛、活性氧水平显著降低;③显著增加黑质区GSH含量。结论:Tet能增强GSH对PD大鼠的抗氧化能力。     

提高帕金森病动物模型制作成功率的方法学探讨及模型综合评价

目的探讨提高6-OHDA帕金森病(PD)大鼠模型制作成功率的方法,并对模型进行综合评价。方法取SD大鼠90只,将6-OHDA立体定向注射于左侧黑质区及中脑腹侧被盖,观察大鼠的行为、黑质抗氧化指标、线粒体呼吸链及黑质细胞形态学的变化。结果①经阿朴吗啡诱导后共筛选出成功模型64只,成功率为71%;②模型大鼠黑质区ROS、MDA水平均明显升高,而GSH-Px活性则明显降低;③模型大鼠黑质区存在线粒体呼吸链功能障碍;④免疫组化发现注射侧黑质区多巴胺能神经元较对侧明显减少(P<0.001);⑤电镜观察发现模型大鼠黑质细胞同时存在凋亡、变性和坏死样改变。结论应用本方法可较快建立稳定的成功率较高的PD大鼠模型,该方法是通过增强氧化应激、干扰线粒体呼吸链功能、诱导凋亡甚至引发坏死等不同机制损毁多巴胺能神经元的,同PD的发病机制基本一致。     

N-乙酰半胱氨酸对帕金森病模型大鼠黑质氧化应激相关指标的影响

目的观察抗氧化剂N-乙酰半胱氨酸(N-acetylcysteine,NAC)对帕金森病(Parkinson's disease,PD)模型大鼠黑质氧化应激相关指标的影响。方法 36只健康雄性SD大鼠随机分为假手术组(sham组)、帕金森病模型组(PD组)和抗氧化剂NAC组(NAC组),每组又分为模型制备成功后4d和8d两个亚组,每个亚组6只。采用颈背部皮下注射鱼藤酮制作帕金森病大鼠模型,微量酶标法检测大鼠黑质谷胱甘肽(GSH)、谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)和丙二醛(MDA)的含量。结果 (1)与sham组相比,PD组各时间点大鼠黑质中GSH、GSH-Px、SOD含量降低(均P0.01),8d组低于4d组(均P0.05);与PD组相比,NAC组大鼠黑质中GSH、GSH-Px、SOD含量增多(均P0.01),8d组高于4d组(均P0.05)。(2)与sham组相比,PD组大鼠黑质中MDA含量增多(均P0.01),8d组高于4d组(P0.05);与PD组相比,NAC组大鼠黑质中MDA含量降低(均P0.01),8d组低于4d组(P0.05)。结论 N-乙酰半胱氨酸可减轻帕金森病模型大鼠的氧化应激损伤,具有神经保护作用。     

α-硫辛酸对帕金森病大鼠脑内多巴胺能神经元的保护作用及其机制探讨

目的观察α-硫辛酸(LA)对鱼藤酮致帕金森(PD)大鼠模型黑质多巴胺能神经元的保护作用。方法健康成年雄性Wistar大鼠背部皮下注射鱼藤酮制备PD大鼠模型,药物治疗组同时给予大鼠腹腔注射LA。采用分光光度法检测大鼠脑内丙二醛(MDA)和还原型谷胱甘肽(GSH),Western blot检测大鼠中脑黑质及纹状体酪氨酸羟化酶(TH)的表达变化。结果与对照组相比,鱼藤酮组大鼠纹状体中MDA明显增高(P<0.01)而GSH含量明显降低(P<0.01),TH蛋白在黑质和纹状体与对照组比较明显降低(P<0.05);LA干预后与鱼藤酮组相比MDA明显降低及GSH明显增高(P<0.05),TH蛋白表达明显增加(P<0.05)。结论氧化应激在PD发病中起着非常重要的作用,LA能有效减轻PD大鼠脑内氧化应激损伤、保护脑内多巴胺能神经体系,同时改善PD样症状。     

不同运动方式和时间对大鼠骨骼肌线粒体呼吸链复合体酶Ⅰ和Ⅳ活性的

背景：急性剧烈运动对机体可造成氧化应激,线粒体生成活性氧造成机体氧化应激和钙离子超负荷,导致骨骼肌功能下降,机体产生疲劳。然而长期规律运动后线粒体产生适应性变化,从而起到保护机体免受过多活性氧损害的作用。 目的：观察不同运动方式和时间对大鼠骨骼肌线粒体呼吸链复合体酶Ⅰ,Ⅳ活性的影响。 方法：48只健康雄性SD大鼠随机等分为正常对照组、无氧运动组、有氧运动组和交替运动组。在大鼠运动2,4,6周的时候分别处死,差速离心提取大鼠骨骼肌线粒体,分光光度法测定线粒体呼吸链复合体酶Ⅰ,Ⅳ的活性。 结果与结论：运动后有氧组、交替组与无氧组线粒体呼吸链复合体酶I的活性随时间先增强而后下降;运动后有氧组与交替组线粒体呼吸链复合体酶Ⅳ的活性随时间而增强,无氧组则下降。说明有氧运动在中长期耐力运动中可有效提高大鼠体内呼吸链复合体酶Ⅰ,Ⅳ的活性,而无氧运动则只能在短期内提高其活性,长时间无氧运动可能导致对线粒体呼吸链复合体酶的损伤,影响骨骼肌工作效率,造成机体疲劳。     

粉防己碱联合谷胱甘肽对帕金森病大鼠的治疗作用

目的探讨粉防己碱(Tet)联合还原型谷胱甘肽(GSH)对帕金森病(PD)大鼠的治疗作用。方法应用定向注射6-羟基多巴胺制作PD大鼠模型;将成功模型随机分为PD组、GSH组、左旋多巴(L-dopa)组、GSH Tet L-dopa组、GSH Tet组,并给予相应药物腹腔注射治疗;给药后对各组大鼠进行阿朴吗啡旋转试验、脑组织黑质谷胱甘肽、纹状体单胺氧化酶B(MAO-B)含量测定;免疫组化法观察脑组织多巴胺能神经元数目;RT-PCR技术检测酪氨酸羟化酶(TH)mRNA含量。结果(1)L-dopa组、GSH Tet L-dopa组、GSH Tet组阿朴吗啡试验旋转圈数较治疗前明显减少(P<0.05～0.01);(2)GSH Tet组脑组织GSH含量明显高于其他治疗组,MAO-B含量明显低于其他治疗组(均P<0.05);(3)GSH Tet组脑组织TH阳性神经元数目显著多于其他各治疗组(均P<0.05);(4)GSH Tet L-dopa组脑组织THmRNA含量高于其他治疗组及PD组(P<0.05～0.01)。结论Tet联合GSH能增强对PD大鼠的治疗作用。     

一种帕金森病大鼠模型的建立及评价

目的探讨应用6-羟基多巴胺（6-OHDA）毁损大鼠黑质致密部制作偏侧帕金森病（PD）模型的方法和应用价值。方法采用立体定向微量注射6-OHDA于大鼠黑质致密部,观察经阿朴吗啡诱导后大鼠的行为及黑质多巴胺能神经元形态学变化。结果部分大鼠注射后即出现行动迟缓、少动、竖毛、躬身、尾部强直、肢体震颤、嗅探和易激惹等异常行为。术后4周时,共33只大鼠经阿朴吗啡诱导后在30min（P〈0．01）的平均旋转圈数〉7r／min,达到成功模型的标准,模型成功率为82．5％（33／40）。免疫组化观察发现模型组大鼠注射侧黑质区多巴胺能神经元较对侧和对照组注射侧区明显减少（P〈0．01）。结论利用6-OHDA毁损大鼠黑质致密部可以较快建立稳定的PD大鼠模型,方法简便实用,动物死亡率低,模型成功率高。     

双靶点注射6-OHDA建立帕金森病大鼠模型并提高成功率

目的建立大鼠帕金森病模型,观测其行为学、中脑黑质多巴胺能神经元及超微结构的变化。方法利用立体定向技术,注射6-OHDA至大鼠中脑黑质SNc和中脑腹侧被盖区VTA,于注射后2、4、6、8周观测阿朴吗啡诱导的大鼠旋转行为学变化;采用免疫组化染色检测TH的表达,了解中脑黑质多巴胺能阳性神经元变化;利用透射电镜了解黑质区超微结构的变化。结果所有大鼠进行阿朴吗啡诱导旋转行为测试,旋转圈数>7r/min,并且>210r/30min,为合格的PD大鼠模型。大鼠模型于第4、6和8周时,大鼠行为学变化较为恒定。第8周时,50只大鼠中出现32只大鼠大鼠旋转次数平均为11.5±1.2/分,造模成功率为64%。PD模型大鼠超微结构观察,黑质神经元数目明显减少,线粒体肿胀,粗面内质网囊性扩张、脱颗粒,髓鞘扩张。免疫组化检测,成功模型光镜下分别计数双侧黑质TH阳性神经元,损毁侧黑质TH阳性神经元占正常侧的3.0%,即毁损侧TH阳性神经元减少97.0%。结论利用立体定向技术,选择黑质和中脑腹侧被盖区等双靶点,可建立6-OHDA大鼠PD模型,具有明确病理变化,提高模型成功率。     

Nigral glutathione deficiency is not specific for idiopathic Parkinson's disease

The consistent findings of decreased levels of the major antioxidant glutathione in substantia nigra of patients with idiopathic Parkinson's disease (PD) has provided most of the basis for the oxidative stress hypothesis of the etiology of PD. To establish whether a nigral glutathione deficiency is unique to PD, as is generally assumed, or is present in other Parkinsonian conditions associated with nigral damage, we compared levels of reduced glutathione (GSH) in postmortem brain of patients with PD to those with progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). As compared with the controls, nigral GSH levels were decreased in the PD and PSP patient groups (P < 0.05 for PD [?30%], PSP [?21%]), whereas a similar decrease in the MSA patient group did not reach statistical significance (P = 0.078, MSA [?20%]). GSH levels were normal in all examined normal and degenerating extra‐nigral brain areas in PSP and MSA. A trend for decreased levels of uric acid (antioxidant and product of purine catabolism) also was observed in nigra of all patient groups (?19 to ?30%). These data suggest that glutathione depletion, possibly consequent to overutilisation in oxidative stress reactions, could play a causal role in nigral degeneration in all nigrostriatal dopamine deficiency disorders, and that antioxidant therapeutic approaches should not be restricted to PD. © 2003 Movement Disorder Society     

高频刺激底丘脑核阻止帕金森病黑质多巴胺能神经元变性的实验研究

目的评价电刺激底丘脑核（ＳＴＮ）对帕金森病黑质多巴胺能神经元变性的影响。方法　实验用大鼠随机分为四组：第１组　纹状体仅注射６－羟基多巴（６－ＯＨＤＡ）;第２组　底丘脑核区插入电极进行刺激组;第３组　底丘脑核刺激后６－ＯＨＤＡ再注射纹状体组;第４组　假刺激底丘脑核后再注射６－ＯＨＤＡ入纹状体组。手术后６周,分别观察各组大鼠阿朴吗啡（ＡＰＯ）诱发旋转行为及黑质多巴胺能神经元改变情况。结果第１、４组出现明显的ＡＰＯ诱发对侧旋转行为,第２、３组出现同侧旋转;酪氨酸羟化酶（ＴＨ）免疫组织化学染色显示,黑质区ＴＨ免疫反应（ＴＨ－ＩＲ）神经元数目在２、３组双侧无明显不同,而１、４组注射侧ＴＨ－ＩＲ神经元数目显著降低（Ｐ＜０．０１）。结论我们的结果表明,ＳＴＮ电刺激可以保护黑质多巴胺能神经元免受６－ＯＨＤＡ的毒性损害,提示这种治疗方法可以阻止或延缓帕金森病的继续发展和恶化。     

p-Quinone mediates 6-hydroxydopamine-induced dopaminergic neuronal death and ferrous iron accelerates the conversion of p-quinone into melanin extracellularly

Parkinson's disease (PD) is characterized by the selective loss of dopaminergic neurons in the substantia nigra (SN). 6-Hydroxydopamine (6-OHDA), a dopaminergic neurotoxin, is detected in human brains and the urine of PD patients. Using SH-SY5Y, a human neuroblastoma cell line, we demonstrated that 6-OHDA toxicity was determined by the amount of p-quinone produced in 6-OHDA auto-oxidation rather than by reactive oxygen species (ROS). Glutathione (GSH), which conjugated with p-quinone, provided significant protection whereas catalase, which detoxified hydrogen peroxide and superoxide anions, failed to block cell death caused by 6-OHDA. Although iron accumulated in the SN of patients with PD can cause dopaminergic neuronal degeneration by enhancing oxidative stress, we found that extracellular ferrous iron promoted the formation of melanin and reduced the amount of p-quinone. The addition of ferrous iron to the culture medium inhibited caspase-3 activation and apoptotic nuclear morphologic changes and blocked 6-OHDA-induced cytotoxicity in SH-SY5Y cells and primary cultured mesencephalic dopaminergic neurons. These data suggested that generation of p-quinone played a pivotal role in 6-OHDA-induced toxicity and extracellular iron in contrast to intracellular iron was protective rather than harmful because it accelerated the conversion of p-quinone into melanin.     

Estrogen and angiotensin interaction in the substantia nigra. Relevance to postmenopausal Parkinson's disease

Epidemiological studies have reported that the incidence of Parkinson's disease (PD) is higher in postmenopausal than in premenopausal women of similar age. Several laboratory observations have revealed that estrogen has protective effects against dopaminergic toxins. The mechanism by which estrogen protects dopaminergic neurons has not been clarified, although estrogen-induced attenuation of the neuroinflammatory response plays a major role. We have recently shown that activation of the nigral renin-angiotensin system (RAS), via type 1 (AT1) receptors, leads to NADPH complex and microglial activation and induces dopaminergic neuron death. In the present study we investigated the effect of ovariectomy and estrogen replacement on the nigral RAS and on dopaminergic degeneration induced by intrastriatal injection of 6-OHDA. We observed a marked loss of dopaminergic neurons in ovariectomized rats treated with 6-OHDA, which was significantly reduced by estrogen replacement or treatment with the AT1 receptor antagonist candesartan. We also observed that estrogen replacement induces significant downregulation of the activity of the angiotensin converting enzyme as well as downregulation of AT1 receptors, upregulation of AT2 receptors and downregulation of the NADPH complex activity in the substantia nigra in comparison with ovariectomized rats. The present results suggest that estrogen-induced down-regulation of RAS and NADPH activity may be associated with the reduced risk of PD in premenopausal women, and increased risk in conditions causing early reduction in endogenous estrogen, and that manipulation of brain RAS system may be an efficient approach for the prevention or coadjutant treatment of PD in estrogen-deficient women.     

Subthalamic nucleus lesions are neuroprotective against terminal 6-OHDA-induced striatal lesions and restore postural balancing reactions

Inactivation of the subthalamic nucleus (STN) by deep brain stimulation or lesioning can ameliorate symptoms in Parkinson' disease (PD) and may alter the underlying progressive degenerative process. We evaluated the effects of STN lesions in a terminal lesion model of PD in rats. Multiple intrastriatal 6-OHDA injections (4 x 7 microg) resulted in a partial loss of striatal TH-positive innervation (-30 to -40%) and nigral dopaminergic neurons (-60%), which was associated with behavioral deficits as observed in drug-induced rotational asymmetry, side-stepping, and postural balancing reactions. Unilateral ibotenic acid lesions of the STN did produce a 50-60% loss of STN neurons based on stereological analysis, which did not induce a functional impairment in rotational asymmetry or spontaneous sensorimotor behaviors. When STN lesions were performed 1 week prior to the 6-OHDA terminal striatal lesions, a significant rescue effect (+23%) on nigral dopaminergic neurons against terminal 6-OHDA neurotoxicity could be demonstrated, whereas striatal TH-positive fiber loss was not attenuated in these animals. In addition, animals with combined STN and striatal lesions exhibited a significant recovery in postural balancing reactions induced by 6-OHDA terminal lesions and did not show a significant impairment in any of the other behavioral parameters examined. Taken together, STN lesions can exert neuroprotective effects on nigral dopamine neurons in a partial lesion model of PD which result in recovery of spontaneous sensorimotor behavior. These findings may therefore provide new insights into the functional interaction between the glutamatergic and the dopaminergic neurotransmitter systems and foster novel therapeutic concepts for the early and middle phases of Parkinson's disease.     

Thioctic acid does not restore glutathione levels or protect against the potentiation of 6-hydroxydopamine toxicity induced by glutathione depletion in rat brain

Summary Decreased reduced glutathione (GSH) levels are an early marker of nigral cell death in Parkinson's disease. Depletion of rat brain GSH by intracerebroventricular administration of buthionine sulphoximine (BSO) potentiates the toxicity of 6-hydroxydopamine (6-OHDA) to the nigrostriatal pathway. We have investigated whether thioctic acid can replenish brain GSH levels following BSO-induced depletion and/or prevent 6-OHDA induced toxicity.Administration of BSO (2 × 1.6 mg ICV) to rats depleted striatal GSH levels by upto 75%. BSO treatment potentiated 6-OHDA (75 g ICV) toxicity as judged by striatal dopamine content and the number of tyrosine hydroxylase immunoreactive cells in substantia nigra. Repeated treatment with thioctic acid (50 or 100mg/kg i.p.) over 48h had no effect on the 6-OHDA induced loss of dopamine in striatum or nigral tyrosine hydroxylase positive cells in substantia nigra. Also thioctic acid treatment did not reverse the BSO induced depletion of GSH or prevent the potentiation of 6-OHDA neurotoxicity produced by BSO.Thioctic acid (50mg or 100mg/kg i.p.) alone or in combination with BSO did not alter striatal dopamine levels but increased dopamine turnover. Striatal 5-HT content was not altered by thioctic acid but 5-HIAA levels were increased.Under conditions of inhibition of GSH synthesis, thioctic acid does not replenish brain GSH levels or protect against 6-OHDA toxicity. At least in this model of Parkinson's disease, thioctic acid does not appear to have a neuroprotective effect.     

rAAV-mediated nigral human parkin over-expression partially ameliorates motor deficits via enhanced dopamine neurotransmission in a rat model of Parkinson's disease

We hypothesized that over-expressing the E3 ligase, parkin, whose functional loss leads to Parkinson's disease, in the nigrostriatal tract might be protective in the unilateral 6-hydroxydopamine (6-OHDA) rat lesion model. Recombinant adeno-associated virus (rAAV) encoding human parkin or green fluorescent protein (GFP) was injected into the rat substantia nigra 6 weeks prior to a four-site striatal 6-OHDA lesion. Vector-mediated parkin over-expression significantly ameliorated motor deficits as measured by amphetamine-induced rotational behavior and spontaneous behavior in the cylinder test but forelimb akinesia as assessed by the stepping test was unaffected. rAAV-mediated human parkin was expressed in the nigrostriatal tract, the substantia pars reticulata, and the subthalamic nucleus. However, in lesioned animals, there was no difference between nigral parkin and GFP-transduction on lesion-induced striatal tyrosine hydroxylase (TH) innervation or nigral TH positive surviving neurons. A second lesion experiment was performed to determine if striatal dopamine (DA) neurotransmission was enhanced as measured biochemically. In this second group of parkin and GFP treated rats, behavioral improvement was again observed. In addition, striatal TH and DA levels were slightly increased in the parkin-transduced group. In a third experiment, we evaluated parkin and GFP transduced rats 6 weeks after vector injection without DA depletion. When challenged with amphetamine, parkin treated rats tended to display asymmetries biased away from the treated hemisphere. Nigral parkin over-expression induced increases in both striatal TH and DA levels. Therefore, while parkin over-expression exerted no protective effect on the nigrostriatal DA system, parkin appeared to enhance the efficiency of nigrostriatal DA transmission in intact nigral DA neurons likely due to the observed increases in TH.