铜离子引起大鼠黑质多巴胺能神经元的退行性变

目的探讨黑质（substantia nigra,SN）内注射不同剂量的CuSO45H2O对大鼠黑质纹状体系统多巴胺能神经元的影响。方法实验用Wistar大鼠,分成对照组和左侧SN内分别注射10nmol、50nmol、200nmol CuSO。组,7天后采用高效液相色谱法（high performance lipid chromotophotography,HPLC）检测纹状体内多巴胺（dopamine,DA）及其代谢产物的含量;酪氨酸羟化酶（tyrosine hydroxylase,TH）免疫组织化学法检测纹状体内TH免疫阳性纤维的改变;半定量RT-PCR法检测黑质内TH,Caspase-3mRNA的表达量：用生化试剂盒分析大鼠中脑内超氧化物岐化酶（superoxide dismutase,SOD）活性的改变。结果在10nmol CuSO4注射组中,DA及其代谢产物的含量与对照组相比没有统计学差别。但是从50nmol组开始,损毁侧纹状体内DA含量随注射CuSO4剂量的增加而逐渐减少,显示出明显的剂量依赖关系（F=34．16,P〈0．01）。注射50nmol CuSO4组大鼠纹状体内TH免疫阳性纤维明显少于对照组和未损毁侧（F=121．9,P〈0．01）。注射50nmol CuSO4组大鼠SN内THmRNA的表达与对照组相比下降（t=3．12,P〈0．01）,但Caspase-3mRNA的表达量与对照组相比却明显增加（t=8．96,P〈0．01）。在注射50nmolCuSO4组中,大鼠损伤侧中脑内SOD的活性与对照组相比下降（t=2．33,P〈0．01）。结论铜离子可以导致大鼠黑质内多巴胺能神经元的损伤,该损伤作用可能是通过破坏抗氧化保护系统和促进细胞凋亡而实现的。

Copper (Cu2+) induces degeneration of dopaminergic neurons in the nigrostriatal system of rats

OBJECTIVE: To study the effects of intranigral injection of different doses of CuSO4.5H2O on dopaminergic neuron in the nigrostriatal system of rats. METHODS: Wistar rats were divided into four groups, including control group, 10 nmol, 50 nmol and 200 nmol copper injected into left substantia nigra (SN) groups. Seven days after the intranigral injection of copper, dopamine (DA) contents in the striatum (Str) were measured by high performance lipid chromotophotography (HPLC); the density of tyrosine hydroxylase (TH) positive axons in the Str was measured by TH staining method; TH and Caspase-3 mRNA expression in the SN were measured by semi-quantitative RT-PCR. We detected the activity of superoxide dismutase (SOD) in the lesioned midbrain of rats using biochemical methods. RESULTS: DA and its metabolites contents had no significant difference between control group and low dose (10 nmol) copper group. But from 50 nmol copper group, DA contents in the lesioned sides were reduced with the increase in the copper doses injected, showing a significant linear correlation (F = 34.16, P < 0.01). In the 50 nmol copper group, TH positive axons in the Str decreased compared with those of the control and unlesioned sides (F = 121.9, P < 0.01). In the 50 nmol copper group, TH mRNA expression decreased (t = 3.12, P < 0.01) while Caspase-3 mRNA expression increased (t = 8.96, P < 0.01) in the SN compared with the control. SOD activity decreased in the midbrain of rats treated with 50 nmol copper compared with that of the control (t = 2.33, P < 0.01). CONCLUSION: Copper could induce damage of dopaminergic neurons in the SN of rats through destroying antioxidant defenses and promoting apoptosis.