Lapi Dominga, Vagnani S, Pignataro G, Esposito E, Paterni M, Colantuoni Antonio
Department of Neuroscience, "Federico II" University Medical School Naples, Italy.
Front Physiol. 2012 Mar 1;3:32. doi: 10.3389/fphys.2012.00032. eCollection 2012.
The aim of this study was to assess the in vivo effects of quercetin on pial microvascular responses during transient bilateral common carotid artery occlusion (BCCAO) and reperfusion. Rat pial microcirculation was visualized by fluorescence microscopy through a closed cranial window. Pial arterioles were classified in five orders of branchings. Capillaries were assigned order 0, the smallest arterioles order 1, and the largest ones order 5. In ischemic rats, 30 min BCCAO and 60 min reperfusion caused arteriolar diameter decrease (by 14.5 ± 3.3% of baseline in order 2), microvascular leakage [0.47 ± 0.04, normalized gray levels (NGL)], leukocyte adhesion in venules (9 ± 2/100 μm venular length, v.l./30 s), and reduction of capillary perfusion (by 40 ± 7% of baseline). Moreover, at the end of BCCAO and reperfusion there was a significant increase in reactive oxygen species (ROS) formation when compared with baseline. Quercetin highest dose determined dilation in all arteriolar orders (by 40 ± 4% of baseline in order 2) and prevented microvascular permeability (0.15 ± 0.02 NGL), leukocyte adhesion (3 ± 1/100 μm v.l./30 s) as well as ROS formation, while capillary perfusion was protected. Inhibition of endothelial nitric oxide synthase (NOS) prior to quercetin reduced arteriolar dilation (order 2 diameter increase by 10.3 ± 2.5% of baseline) and caused permeability increase (0.29 ± 0.03 NGL); inhibition of neuronal NOS or inducible NOS did not affect quercetin-induced effects. Inhibition of guanylyl cyclase prior to quercetin reversed the quercetin's effects on pial arteriolar diameter and leakage. In conclusion, quercetin was able to protect pial microcirculation from ischemia-reperfusion damage inducing arteriolar dilation likely by nitric oxide release. Moreover, quercetin scavenger activity blunted ROS formation preserving the blood-brain barrier integrity.
本研究的目的是评估槲皮素在短暂双侧颈总动脉闭塞（BCCAO）及再灌注过程中对软脑膜微血管反应的体内作用。通过封闭的颅骨视窗，利用荧光显微镜观察大鼠软脑膜微循环。软脑膜小动脉按分支顺序分为五级。毛细血管为0级，最小的小动脉为1级，最大的为5级。在缺血大鼠中，30分钟的BCCAO和60分钟的再灌注导致小动脉直径减小（2级小动脉直径减小至基线的14.5±3.3%）、微血管渗漏[0.47±0.04，归一化灰度值（NGL）]、小静脉内白细胞黏附（9±2/100μm静脉长度，v.l./30秒）以及毛细血管灌注减少（至基线的40±7%）。此外，与基线相比，在BCCAO和再灌注结束时活性氧（ROS）生成显著增加。槲皮素的最高剂量可使各级小动脉扩张（2级小动脉直径增加至基线的40±4%），并防止微血管通透性增加（0.15±0.02 NGL）、白细胞黏附（3±1/100μm v.l./30秒）以及ROS生成，同时保护毛细血管灌注。在给予槲皮素之前抑制内皮型一氧化氮合酶（NOS）可减少小动脉扩张（2级小动脉直径增加至基线的10.3±2.5%）并导致通透性增加（0.29±0.03 NGL）；抑制神经元型NOS或诱导型NOS并不影响槲皮素诱导的效应。在给予槲皮素之前抑制鸟苷酸环化酶可逆转槲皮素对软脑膜小动脉直径和渗漏的影响。总之，槲皮素能够保护软脑膜微循环免受缺血再灌注损伤，可能是通过释放一氧化氮诱导小动脉扩张。此外，槲皮素的清除剂活性可抑制ROS生成，维持血脑屏障的完整性。
