Senn Claudia, Hangartner Christoph, Moes Suzette, Guerini Danilo, Hofbauer Karl G
Applied Pharmacology, Biozentrum, University of Basel, Switzerland.
Eur J Pharmacol. 2005 Oct 17;522(1-3):30-7. doi: 10.1016/j.ejphar.2005.08.021. Epub 2005 Oct 6.
To date there are only few reports of the use of small interfering RNA (siRNA) in whole animals and most of these are restricted to systemic application of siRNAs targeting the liver. In our present studies we have investigated whether siRNAs can be used against a central target after intracerebroventricular (i.c.v.) application and compared their effects with those of antisense oligonucleotides. For this purpose we designed different siRNA and antisense oligonucleotide molecules against the rat hypothalamic melanocortin MC(4) receptor and selected the siRNA and antisense oligonucleotide with the highest efficacy in vitro. We observed that siRNA, encompassing the same gene sequence as antisense oligonucleotides, induced a stronger inhibition of melanocortin MC(4) receptor expression than antisense oligonucleotides. When fluorescence-labeled siRNA were applied i.c.v. in rats no label was detected in brain tissue in spite of the use of cell detergents to improve the delivery. In contrast to these findings the i.c.v. administered fluorescence-labeled antisense oligonucleotides reached the brain structures expressing melanocortin MC(4) receptor and were taken up by the cells in these areas. In summary it seems as if 'naked' antisense oligonucleotides have an advantage over 'naked' siRNA for experiments in vivo. The development of optimized vector systems seems to be a prerequisite before siRNA can be regarded as a suitable experimental tool for in vivo studies.
迄今为止，仅有少数关于在整体动物中使用小干扰RNA（siRNA）的报道，并且其中大多数仅限于全身性应用靶向肝脏的siRNA。在我们目前的研究中，我们研究了在脑室内（i.c.v.）应用后siRNA是否可用于针对中枢靶点，并将其效果与反义寡核苷酸的效果进行比较。为此，我们针对大鼠下丘脑黑皮质素MC(4)受体设计了不同的siRNA和反义寡核苷酸分子，并选择了体外效果最佳的siRNA和反义寡核苷酸。我们观察到，与反义寡核苷酸包含相同基因序列的siRNA对黑皮质素MC(4)受体表达的抑制作用比反义寡核苷酸更强。当将荧光标记的siRNA经脑室内注射到大鼠体内时，尽管使用了细胞去污剂来改善递送，但在脑组织中未检测到标记。与这些发现相反，经脑室内注射的荧光标记反义寡核苷酸到达了表达黑皮质素MC(4)受体的脑结构，并被这些区域的细胞摄取。总之，在体内实验中，“裸”反义寡核苷酸似乎比“裸”siRNA具有优势。在siRNA可被视为体内研究的合适实验工具之前，开发优化的载体系统似乎是一个先决条件。
