Sivam S P
Department of Pharmacology & Toxicology, Indiana University School of Medicine, Gary 46408, USA.
Brain Res Mol Brain Res. 1996 Jan;35(1-2):197-210. doi: 10.1016/0169-328x(95)00216-f.
The present study examined the modulatory role of dopamine (DA) on striatonigral preprotachykinin (PPT) and prodynorphin (PD) gene expression, employing the DA uptake inhibitor, GBR-12909 (GBR), as a tool. The striatal and nigral levels of tachykinin (substance P (SP), neurokinin A (NKA)) and dynorphin (dynorphin A(1-8) (DYN)) peptides were determined by radioimmunoassays. The abundance of mRNAs in the striatum was quantified by Northern blot analysis. The rate of transcription of PPT and PD genes in the striatum was measured by transcription run-on assays. A regimen of repeated administration of GBR (20 mg/kg/day, i.p., for 1-4 days) to female Sprague-Dawley rats increased striatal and nigral SP, NKA, and DYN peptide levels. The increased peptide levels were associated with increases in the abundance of PD mRNA and PPT mRNA and increases in the rate of transcription of PD and PPT genes in the striatum, suggesting a GBR-induced activation of the striatonigral tachykinin and dynorphin neurons. Dopaminergic denervation with 6-hydroxydopamine (6OHDA) blocked the GBR-induced increases in SP and DYN and PPT and PD mRNAs. The concurrent administration of the D1 DA antagonist, SCH-23390, blocked the GBR-induced increases in SP, NKA and PPT mRNA but failed to affect DYN or PD mRNA levels; the concurrent administration of the D2 DA antagonist, spiperone, blocked the GBR-induced increases in SP, NKA and PPT mRNA and also DYN and PD mRNA. The study reveals that repeated administration of GBR enhances the levels of tachykinin and dynorphin peptides in striatonigral neurons by a stimulus-transcription-biosynthesis coupling mechanism. The GBR-induced effects are dependent on the integrity of nigrostriatal dopaminergic neurons and the presence of D1 and/or D2 DA receptors.
本研究使用多巴胺摄取抑制剂GBR-12909（GBR）作为工具，检测多巴胺（DA）对纹状体黑质前速激肽（PPT）和前强啡肽（PD）基因表达的调节作用。通过放射免疫分析法测定速激肽（P物质（SP）、神经激肽A（NKA））和强啡肽（强啡肽A（1-8）（DYN））肽在纹状体和黑质中的水平。通过Northern印迹分析对纹状体中mRNA的丰度进行定量。通过转录延伸分析测量纹状体中PPT和PD基因的转录速率。对雌性Sprague-Dawley大鼠重复给予GBR（20mg/kg/天，腹腔注射，持续1-4天）的方案可提高纹状体和黑质中SP、NKA和DYN肽的水平。肽水平的升高与纹状体中PD mRNA和PPT mRNA丰度的增加以及PD和PPT基因转录速率的增加相关，提示GBR诱导纹状体黑质速激肽和强啡肽神经元的激活。用6-羟基多巴胺（6OHDA）进行多巴胺能去神经支配可阻断GBR诱导的SP、DYN以及PPT和PD mRNA的增加。同时给予D1 DA拮抗剂SCH-23390可阻断GBR诱导的SP、NKA和PPT mRNA的增加，但未能影响DYN或PD mRNA水平；同时给予D2 DA拮抗剂螺哌隆可阻断GBR诱导的SP、NKA和PPT mRNA的增加，以及DYN和PD mRNA的增加。该研究表明，重复给予GBR通过刺激-转录-生物合成偶联机制提高纹状体黑质神经元中速激肽和强啡肽肽的水平。GBR诱导的效应依赖于黑质纹状体多巴胺能神经元的完整性以及D1和/或D2 DA受体的存在。
