Therapeutic effects of KCC2 chloride transporter activation on detrusor overactivity in mice with spinal cord injury
Therapeutic effects of KCC2 chloride transporter activation on detrusor overactivity in mice with spinal cord injury
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DOI：
10.1152/ajprenal.00271.2022
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发表时间：
2023-04-01
影响因子：
4.2
通讯作者：
Fukuda，Atsuo
中科院分区：
文献类型：
--
作者：
Watanabe，Kyohei;Ishibashi，Masaru;Fukuda，Atsuo
本研究旨在阐明在脊髓损伤(SCI)过程中，支配膀胱的传出通路--腰椎副交感神经核内K+-C l−协同转运体2(KCC2)的表达下调是否会导致细胞过度兴奋并引发逼尿肌过度活动(DO)。雌性C57BL/6小鼠Th8-9脊髓横断造成脊髓损伤。脊髓损伤后4wk，给予KCC2激活剂CLP290，并进行膀胱测压。免疫组织化学方法检测SPN内胆碱能节前副交感神经元的c-fos染色和KCC2表达。通过脊髓切片细胞外记录来评价SPN区神经元的放电特性。CLP290可显著减少脊髓损伤小鼠的DO，表现为非排尿收缩。脊髓损伤CLP290治疗组脊髓SPN区c-fos阳性细胞数和胆碱乙酰转移酶阳性细胞中c-fos共表达均低于脊髓损伤赋形剂组。脊髓损伤组SPN神经元胞膜上有KCC2免疫反应阳性，胆碱乙酰转移酶阳性神经元KCC2的归一化荧光强度低于脊髓完整载体治疗组，但CLP290治疗组恢复正常。细胞外记录显示，CLP290抑制脊髓损伤小鼠SPN神经元的高频放电活动。这些结果表明，脊髓损伤引起的DO与节前副交感神经元KCC2表达下调有关，KCC2转运体的激活可以减少DO，增加节前副交感神经元KCC2的表达，减少脊髓损伤小鼠SPN神经元的放电。本研究首次提出，激活CL-−转运体K+-CL-−共转运体2可能是通过靶向膀胱传出通路治疗脊髓损伤所致逼尿肌过度活动的治疗手段。
This study aimed to clarify whether downregulation of K+-Cl−cotransporter 2 (KCC2) in the sacral parasympathetic nucleus (SPN) of the lumbosacral spinal cord, from which the efferent pathway innervating the bladder originates, causes cellular hyperexcitability and triggers detrusor overactivity (DO) in spinal cord injury (SCI). SCI was produced by Th8-9 spinal cord transection in female C57BL/6 mice. At 4 wk after SCI, CLP290, a KCC2 activator, was administered, and cystometry was performed. Thereafter, neuronal activity with c-fos staining and KCC2 expression in cholinergic preganglionic parasympathetic neurons in the SPN was examined using immunohistochemistry. Firing properties of neurons in the SPN region were evaluated by extracellular recordings in the spinal cord slice preparations. DO evident as nonvoiding contractions was significantly reduced by CLP290 treatment in SCI mice. The number of c-fos-positive cells and coexpression of c-fos in choline acetyltransferase-positive cells were decreased in the SPN region of the SCI CLP290-treated group versus the SCI vehicle-treated group. KCC2 immunoreactivity was present on the cell membrane of SPN neurons and normalized fluorescence intensity of KCC2 in choline acetyltransferase-positive SPN neurons was decreased in the SCI vehicle-treated group versus the spinal intact vehicle-treated group but recovered in the SCI CLP290-treated group. Extracellular recordings showed that CLP290 suppressed the high-frequency firing activity of SPN neurons in SCI mice. These results indicated that SCI-induced DO is associated with downregulation of KCC2 in preganglionic parasympathetic neurons and that activation of KCC2 transporters can reduce DO, increase KCC2 expression in preganglionic parasympathetic neurons, and decrease neuronal firing of SPN neurons in SCI mice.NEW & NOTEWORTHYThis study is the first report to suggest that activation of the Cl−transporter K+-Cl−cotransporter 2 may be a therapeutic modality for the treatment of spinal cord injury-induced detrusor overactivity by targeting bladder efferent pathways.