siRNA-mediated knockdown of the serotonin transporter in the adult mouse brain
siRNA-mediated knockdown of the serotonin transporter in the adult mouse brain
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DOI：
10.1038/sj.mp.4001687
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发表时间：
2005-08-01
影响因子：
11
通讯作者：
Cryan, JF
中科院分区：
文献类型：
--
作者：
Thakker, DR;Natt, F;Cryan, JF
选择性5-羟色胺再摄取抑制剂(SSRI)是广泛使用的抗抑郁药物，通过阻断5-羟色胺转运体(SERT)的再摄取活性来增加细胞外5-羟色胺水平。尽管SSRI显著提高了大脑5-羟色胺能神经传递，但它们的全部治疗效果涉及到长期给药后出现的神经化学适应。SERT的适应性下调最近被认为与SSRIs的治疗反应有关。有趣的是，使用SERT基因敲除小鼠的研究揭示了一些与抑郁相关的自相矛盾的效应，可能特定于SERT在发育早期的下调。然而，SSRI介导的SERT在成年期下调的行为学意义仍不清楚。我们研究了将短干扰RNA(SiRNA)注入脑室系统触发的体细胞基因操作是否能够下调成年小鼠大脑中SERT的表达。注入靶向SERT的siRNA 2周后，可显著降低中缝核内SERT的mRNA水平。此外，在大脑中实现了SERT结合位点的显著、特异和广泛的下调。相比之下，注射SSRI西酞普兰2周后，SERT结合位点普遍下调，与mRNA水平的任何变化无关。不管它们下调大脑中SERT的机制，SERT-siRNA或西酞普兰的输注在强迫游泳测试中引起了类似的抗抑郁相关行为反应。这些结果表明SERT的下调在介导SSRIs在成人中的抗抑郁作用中起到了作用。此外，这些数据表明，siRNA诱导的广泛的基因表达下调是评估成人大脑内源性基因功能的有力工具。
Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressant drugs that increase the extracellular levels of serotonin by blocking the reuptake activity of the serotonin transporter (SERT). Although SSRIs elevate brain serotonergic neurotransmission acutely, their full therapeutic effects involve neurochemical adaptations that emerge following chronic drug administration. The adaptive downregulation of SERT has recently been implicated in the therapeutic response of SSRIs. Interestingly, studies using SERT-knockout mice reveal somewhat paradoxical depression-related effects, probably specific to the downregulation of SERT during early development. However, the behavioral significance of SSRI-mediated downregulation of SERT during adulthood is still unknown. We investigated whether somatic gene manipulation, triggered by infusing short interfering RNA ( siRNA) into the ventricular system, would enable the downregulation of SERT in the adult mouse brain. Infusing the SERT-targeting siRNA, for 2 weeks, significantly reduced the mRNA levels of SERT in raphe nuclei. Further, a significant, specific and widespread downregulation of SERT-binding sites was achieved in the brain. In contrast, 2-week infusion of the SSRI, citalopram, produced a widespread downregulation of SERT-binding sites, independent of any alterations at the mRNA level. Irrespective of their mechanisms for downregulating SERT in the brain, infusions of SERT-siRNA or citalopram elicited a similar antidepressant-related behavioral response in the forced swim test. These results signify a role for the downregulation of SERT in mediating the antidepressant action of SSRIs in adults. Further, these data demonstrate that siRNA-induced widespread knockdown of gene expression serves as a powerful tool for assessing the function of endogenous genes in the adult brain.