Eleore Lyndell, Ardehali Mohamed Reza, Vassias Isabelle, Vidal Pierre-Paul, de Waele Catherine
LNRS (CNRS-Paris 5), Centre Universitaire des Saints-Pères, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France.
Exp Brain Res. 2007 Oct;182(4):449-58. doi: 10.1007/s00221-007-1006-0. Epub 2007 Jun 28.
We report the first investigation of whether unilateral labyrinthectomy in adult rats affects the expression of two amino acid transporters, vesicular glutamate transporter 2 (VGLUT2) and vesicular inhibitory amino acid transporter (VIAAT) and of chloride cotransporters (KCC1, KCC2 and NKCC1) in the intact and deafferented medial vestibular nuclei (MVN). In situ hybridization with specific radioactive oligonucleotide probes and immunofluorescent methods were used in normal and unilaterally labyrinthectomized rats at various times following the lesion: 5 h, and 1, 3 and 8 days. In normal animals, several brainstem regions including the lateral, medial, superior and inferior vestibular nuclei contained VGLUT2, VIAAT and KCC2 mRNA. In contrast, no or a very faint labeling was observed with KCC1 and NKCC1 probes. In unilaterally lesioned rats, there was no asymmetry between the two MVN with any of the oligonucleotide probes at any time after the lesion. Similarly, there were no differences in the intensity of MVN labeling between controls and lesioned animals. Finally, no over-expression of the cotransporter KCC1 and NKCC1 was found in ipsilateral or controlateral MVN in lesioned rats at any time. Immunohistochemical experiments gave similar conclusions. Our findings suggest that the recovery of the resting discharge of the deafferented MVN neurons, and consequently the functional compensation of the deficits, are not dependent on changes in the expression of amino acid transporters (VIAAT, VGLUT2), and chloride cotransporters (KCC1, KCC2 and NKCC1) or on their mRNAs.
我们报告了关于成年大鼠单侧迷路切除术是否会影响完整及去传入神经的内侧前庭核（MVN）中两种氨基酸转运体，即囊泡谷氨酸转运体2（VGLUT2）和囊泡抑制性氨基酸转运体（VIAAT）以及氯化物共转运体（KCC1、KCC2和NKCC1）表达的首次研究。在损伤后的不同时间点（5小时、1天、3天和8天），对正常和单侧迷路切除的大鼠使用特异性放射性寡核苷酸探针进行原位杂交以及免疫荧光方法。在正常动物中，包括外侧、内侧、上和下前庭核在内的几个脑干区域含有VGLUT2、VIAAT和KCC2 mRNA。相比之下，用KCC1和NKCC1探针未观察到标记或仅有非常微弱的标记。在单侧损伤的大鼠中，损伤后任何时间，两种MVN之间用任何一种寡核苷酸探针均未出现不对称。同样，对照组和损伤动物的MVN标记强度也没有差异。最后，在损伤大鼠的同侧或对侧MVN中，任何时间均未发现共转运体KCC1和NKCC1的过表达。免疫组织化学实验得出了类似的结论。我们的研究结果表明，去传入神经的MVN神经元静息放电的恢复以及因此对缺陷的功能补偿，不依赖于氨基酸转运体（VIAAT、VGLUT2）和氯化物共转运体（KCC1、KCC2和NKCC1）及其mRNA表达的变化。
