Tomizawa Atsuyuki, Ishii Itsuko, Zhelev Zhivko, Aoki Ichio, Shibata Sayaka, Kitada Mitsukazu, Bakalova Rumiana
Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
Biochim Biophys Acta. 2011 Dec;1810(12):1309-16. doi: 10.1016/j.bbagen.2011.06.011. Epub 2011 Jun 29.
Gd-DTPA-enhanced magnetic resonance imaging (MRI) is a conventional method for non-invasive investigation of blood-brain-barrier (BBB) permeability in animal models. It allows the visualization of serious injury to the BBB. We developed a novel approach for detecting very small disruptions in BBB permeability induced by dietary cholesterol by using carbamoyl-PROXYL (CMP) as an MRI contrast probe.
Mice were separated into two groups: normal diet (ND-mice) and high cholesterol diet (CD-mice). MRI-signal dynamics, plasma cholesterol, matrix metalloproteinase (MMP-9, MMP-2), and the white blood cell profile were analyzed. For the MRI analysis, two regions-of-interest (ROI) were selected: brain (ROI-1) and surrounding area (ROI-2).
In the ROI-2 of ND-mice, CMP- or Gd-enhanced MRI-signal followed typical kinetics with a half-life of signal decay (τ(1/2)) approximately 8 or approximately 15 min, respectively. In CD-mice, the MRI-signal increased continuously without decay. In the ROI-1 of ND- and CD-mice, MRI-signal enhancement was not detected by Gd-DTPA. In the ROI-1 of ND-mice, CMP-induced MRI-signal enhancement was negligible, while in CD-mice, it was significant (τ(1/2)>15 min). Hypercholesterolemia increased the plasma levels of MMP-9 and neutrophils.
Hypercholesterolemia increases vascular permeability, which is mediated by MMP-9 and neutrophils.
Even very small disruptions in brain vascular permeability could be detected by CMP-enhanced MRI but not by Gd-DTPA-enhanced MRI.
钆喷酸葡胺增强磁共振成像（MRI）是在动物模型中对血脑屏障（BBB）通透性进行无创研究的常规方法。它能够可视化血脑屏障的严重损伤。我们开发了一种新方法，通过使用氨甲酰 - 脯氨酰自由基（CMP）作为MRI造影剂来检测饮食胆固醇诱导的血脑屏障通透性的微小破坏。
将小鼠分为两组：正常饮食组（ND小鼠）和高胆固醇饮食组（CD小鼠）。分析MRI信号动力学、血浆胆固醇、基质金属蛋白酶（MMP - 9、MMP - 2）和白细胞谱。对于MRI分析，选择两个感兴趣区域（ROI）：脑（ROI - 1）和周围区域（ROI - 2）。
在ND小鼠的ROI - 2中，CMP或钆增强的MRI信号遵循典型动力学，信号衰减半衰期（τ(1/2)）分别约为8分钟或约15分钟。在CD小鼠中，MRI信号持续增加且无衰减。在ND和CD小鼠的ROI - 1中，钆喷酸葡胺未检测到MRI信号增强。在ND小鼠的ROI - 1中，CMP诱导的MRI信号增强可忽略不计，而在CD小鼠中则很显著（τ(1/2)>15分钟）。高胆固醇血症增加了MMP - 9和中性粒细胞的血浆水平。
高胆固醇血症增加血管通透性，这由MMP - 9和中性粒细胞介导。
即使是脑血管通透性的非常微小的破坏也可以通过CMP增强的MRI检测到，但钆喷酸葡胺增强的MRI则无法检测到。
