1] Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan [2] Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
Department of Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
J Cereb Blood Flow Metab. 2014 Apr;34(4):589-96. doi: 10.1038/jcbfm.2013.234. Epub 2014 Jan 8.
C-type natriuretic peptide (CNP) is abundant in brain and is reported to exert autocrine function in vascular cells, but its effect on blood-brain barrier (BBB) permeability has not been clarified yet. Here, we examined this effect. Transendothelial electrical resistance (TEER) of in vitro BBB model, composed of bovine brain microvascular endothelial cells and astrocytes, was significantly dose dependently decreased by CNP (1, 10, and 100 nmol/L). C-type natriuretic peptide treatment reduced both the messenger RNA (mRNA) and protein expressions of tight junction (TJ) protein zonula occludens-1 (ZO-1). The effects on TEER, mRNA, and protein expressions of ZO-1 were mimicked by cyclic GMP (cGMP) analog 8-bromo-cGMP (1 μmol/L) and reversed by protein kinase G (PKG) inhibitor Rp-8-CPT-cGMPS (100 μmol/L), thus implying the role of PKG and cGMP signaling in BBB function. Transcription factor JunD knockdown by small interfering RNA resulted in no change of permeability by CNP. In vivo study of mouse brain by fluorimetric analysis with intravenous administration of sodium fluorescein (40 mg/kg) also showed a significant increase in BBB permeability by CNP (10 nmol/kg, intravenously). These findings suggest that CNP modulates the BBB permeability by altering ZO-1 expression.
C 型利钠肽（CNP）在脑中含量丰富，据报道其在血管细胞中发挥自分泌功能，但它对血脑屏障（BBB）通透性的影响尚未阐明。在这里，我们研究了这种作用。由牛脑微血管内皮细胞和星形胶质细胞组成的体外 BBB 模型的跨内皮电阻（TEER），被 CNP（1、10 和 100nmol/L）显著地剂量依赖性降低。CNP 处理降低了紧密连接（TJ）蛋白闭合蛋白-1（ZO-1）的信使 RNA（mRNA）和蛋白表达。环鸟苷酸（cGMP）类似物 8-溴-cGMP（1μmol/L）模拟了对 TEER、mRNA 和 ZO-1 蛋白表达的作用，蛋白激酶 G（PKG）抑制剂 Rp-8-CPT-cGMPS（100μmol/L）逆转了这些作用，这表明 PKG 和 cGMP 信号在 BBB 功能中起作用。通过小干扰 RNA 敲低转录因子 JunD，CNP 引起的通透性变化没有改变。通过静脉注射荧光素（40mg/kg）对小鼠脑进行体内荧光分析的研究也表明，CNP（10nmol/kg，静脉内）显著增加了 BBB 的通透性。这些发现表明，CNP 通过改变 ZO-1 的表达来调节 BBB 的通透性。
