Background Proper neuronal function is directly dependent on the composition, turnover, and amount of interstitial fluid that bathes the cells. Most of the interstitial fluid is likely to be derived from ion and water transport across the brain capillary endothelium, a process that may be altered in hypertension due to vascular pathologies as endothelial dysfunction and arterial remodelling. In the current study, we investigated the effects of hypertension on the brain for differences in the water homeostasis. Methods Magnetic resonance imaging (MRI) was performed on a 7T small animal MRI system on male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) of 10 months of age. The MRI protocol consisted of T2-weighted scans followed by quantitative apparent diffusion coefficient (ADC) mapping to measure volumes of different anatomical structures and water diffusion respectively. After MRI, we assessed the spatial distribution of aquaporin 4 expression around blood vessels. Results MRI analysis revealed a significant reduction in overall brain volume and remarkably higher cerebroventricular volume in SHR compared to WKY. Whole brain ADC, as well as ADC values of a number of specific anatomical structures, were significantly lower in hypertensive animals. Additionally, SHR exhibited higher brain parenchymal water content. Immunohistochemical analysis showed a profound expression of aquaporin 4 around blood vessels in both groups, with a significantly larger area of influence around arterioles. Evaluation of specific brain regions revealed a decrease in aquaporin 4 expression around capillaries in the corpus callosum of SHR. Conclusion These results indicate a shift in the brain water homeostasis of adult hypertensive rats.

中文翻译：

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动脉高血压大鼠模型中脑液管理的改变

背景 适当的神经元功能直接取决于沐浴细胞的间质液的组成、周转和数量。大多数间质液可能来自跨脑毛细血管内皮的离子和水运输，这一过程可能在高血压中由于血管病变如内皮功能障碍和动脉重塑而改变。在当前的研究中，我们调查了高血压对大脑中水稳态差异的影响。方法在7T小动物MRI系统上对10个月大的雄性自发性高血压大鼠（SHR）和血压正常的Wistar京都大鼠（WKY）进行磁共振成像（MRI）。MRI 协议包括 T2 加权扫描，然后是定量表观扩散系数 (ADC) 映射，以分别测量不同解剖结构和水扩散的体积。MRI 后，我们评估了血管周围水通道蛋白 4 表达的空间分布。结果 MRI 分析显示，与 WKY 相比，SHR 的整体脑容量显着减少，脑室容量显着增加。高血压动物的全脑 ADC 以及许多特定解剖结构的 ADC 值显着降低。此外，SHR 表现出更高的脑实质含水量。免疫组织化学分析显示，两组的血管周围水通道蛋白 4 均显着表达，小动脉周围的影响区域明显更大。对特定大脑区域的评估显示 SHR 胼胝体毛细血管周围水通道蛋白 4 的表达降低。结论这些结果表明成年高血压大鼠的脑水稳态发生了变化。