Transcriptome profiling in 6-hydroxydopamine hemiparkinsonian rats reveals methamphetamine-mediated dopamine-independent changes in striatal gene expression.. Rattus norvegicus

Unilateral injections of 6-hydroxydopamine into the medial forebrain bundle (MFB) is used extensively as a model of Parkinson’s disease. The present experiments examined whether a single injection of methamphetamine (METH) (2.5 mg/kg) could still influence striatal gene expression after 6-hydroxydopamine (DA)-induced destruction of the nigrostriatal dopaminergic pathway in the rat. Unilateral injections of 6-hydroxydopamine into the MFB resulted in total striatal dopamine depletion on the lesioned side. This injection also caused decreased striatal serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels. DA depletion was associated with increases in 5-HIAA/5-HT ratios which were potentiated by the METH injection. Microarray analyses revealed changes (+ 1.7-fold, p < 0.025) in the expression of 67 genes on the lesioned side in comparison to the intact side of the saline-treated hemiparkinsonian animals. These include follistatin, neuromedin U, and tachykinin 2 which were up-regulated. METH administration caused increases in the expression of several genes including c-fos, Egr1, and NOR-1 on the intact side. On the DA-depleted side, METH administration also increased the expression of 61 genes including Pdgfd and COX-2. There were METH-induced changes in 16 genes that were common in the DA-innervated and DA-depleted sides. These include c-fos and NOR-1 which show greater changes on the normal DA side. The present study documents METH-mediated DA-independent transcriptional alterations of several genes in the DA-denervated striatum. Our results also implicate serotonin as an important player in METH-induced gene expression because the METH injection also caused significant increases in 5-HIAA/5-HT ratios on the DA-depleted side. Overall design: 31 samples. MNL (6), ML (6), SNL (5), SL (6), CS (4), CM (4)

将6-羟基多巴胺（6-hydroxydopamine）单侧注射至内侧前脑束（medial forebrain bundle, MFB），是目前广泛应用的帕金森病（Parkinson’s disease）模型造模手段。本实验旨在探究：在大鼠体内，经6-羟基多巴胺（多巴胺, DA）诱导损毁黑质纹状体多巴胺能通路后，单次注射甲基苯丙胺（methamphetamine, METH，2.5 mg/kg）是否仍可对纹状体基因表达产生影响。
将6-羟基多巴胺单侧注射至MFB可导致损伤侧纹状体多巴胺完全耗竭，同时还会引起纹状体血清素（serotonin, 5-HT）与5-羟吲哚乙酸（5-hydroxyindoleacetic acid, 5-HIAA）水平下降。多巴胺耗竭会伴随5-HIAA/5-HT比值升高，而甲基苯丙胺注射可进一步升高该比值。
基因芯片分析显示，与生理盐水处理的偏侧帕金森病动物的未损伤侧相比，损伤侧共有67个基因的表达出现1.7倍变化（p < 0.025），其中包括上调的卵泡抑素（follistatin）、神经介素U（neuromedin U）以及速激肽2（tachykinin 2）。
甲基苯丙胺给药可在未损伤侧诱导多个基因表达上调，包括c-fos、早期生长反应因子1（Early growth response 1, Egr1）以及NOR-1。在多巴胺耗竭侧，甲基苯丙胺给药同样可上调包括血小板源性生长因子D（Platelet-derived growth factor D, Pdgfd）与环氧合酶2（Cyclooxygenase-2, COX-2）在内的61个基因的表达。
有16个基因的表达变化在多巴胺能神经支配侧与多巴胺耗竭侧中均存在甲基苯丙胺诱导的差异，其中包括c-fos与NOR-1，二者在正常多巴胺能侧的表达变化更为显著。
本研究证实，在多巴胺去神经支配的纹状体中，甲基苯丙胺可介导不依赖多巴胺的多种基因转录改变。本研究结果同时表明，血清素在甲基苯丙胺诱导的基因表达过程中发挥关键作用，因为甲基苯丙胺注射同样可在多巴胺耗竭侧显著升高5-HIAA/5-HT比值。
实验整体设计：共31份样本，分组为MNL（6）、ML（6）、SNL（5）、SL（6）、CS（4）、CM（4）