鱼藤酮对大鼠中脑黑质神经元多巴胺转运体的影响

目的研究鱼藤酮对大鼠中脑黑质神经元多巴胺转运体的影响。方法雄性健康SD大鼠80只,随机分为正常对照组、溶剂对照组和鱼藤酮注射组(1.0mg/kg和1.5mg/kg)。溶剂对照组和鱼藤酮注射组大鼠分别于背部皮下注射溶剂和鱼藤酮,每日1次,28d后处死动物,取脑,冰上分离中脑黑质组织。采用Western blot和免疫组化染色观察酪氨酸羟化酶及多巴胺转运体的蛋白表达,RT-PCR检测多巴胺转运体和多巴胺受体的基因表达,生化实验分析Na -K -ATP酶活性。结果鱼藤酮注射组大鼠中脑黑质组织酪氨酸羟化酶免疫阳性的多巴胺神经元数量减少,酪氨酸羟化酶蛋白表达降低,多巴胺转运体蛋白和基因表达增加,Na -K -ATP酶活性降低,多巴胺Ⅱ型受体表达增加,1.5mg/kg剂量组变化较1.0mg/kg剂量组变化更为显著。结论鱼藤酮对大鼠中脑黑质组织多巴胺神经元具有毒性作用,多巴胺转运体功能异常在鱼藤酮多巴胺神经元毒性中可能具有重要作用。

Effect of rotenone on dopamine transporters in the substantia nigra of rats

Objective To investigate the toxic effects of rotenone on dopamine transporter in the substantia nigra of the rat. Methods Rats (male) were divided into normal control group, vehicle control group and rotenone experimental group(1.0mg/kg and 1.5mg/kg). The animals were subcutaneously administrated with the vehicle or rotenone in different dosage once a day for 28 days. One day after last injection, the brain was dissected and the substantia nigra was harvested. Protein expressions of tyrosine hydroxylase and dopamine transporter were determined with the methods of immunohistochemistry and Western blot. The mRNA expressions of dopamine transporter and dopamine receptor were detected with RT-PCR respectively. The activity of Na -K -ATPase was assayed biochemically. Results In the experimental groups, both the immune positive neurons of tyrosine hydroxylase and the expression of its protein were significantly decreased in the substantia nigra of the rats after rotenone treatment. The number of dopamine transporter antibody-immune positive neurons were significantly increased in the rats exposed to rotenone. Furthermore, protein and mRNA expressions of dopamine transporter in the experimental group were also obviously up-regulated compared with the normal control group. A decreased activity of Na -K -ATPase was observed in the substantia nigra of rats in the rotenone experimental group. In addition, the mRNA expression of D2R was also increased in contrast with that in the control group. Conclusions Rotenone is toxic to dopamine neurons in the substantia nigra of rats. Dysfunction of dopamine transporter may be involved in the mechanism of rotenone toxicity to dopamine neurons.