To elucidate the molecular mechanism by which antioxidants alleviate atherosclerosis, we nvestigated the effect of crocetin, a naturally occurred carotinoid with potent antioxidant power, on vascular cell adhesion molecule-1 (VCAM-1) expression in atherosclerotic rabbits. Twenty-four male New Zealand White rabbits were allocated to three groups fed on standard diet (control group), high lipid diet (HLD group) or high lipid diet supplemented with crocetin (crocetin group), respectively. After 8 weeks of treatment, rabbits in HLD group developed severe hypercholesterolemia and atherosclerosis in aortas, together with a significantly up-regulated expression of both protein and mRNA for VCAM-1. In contrast, supplementation with crocetin resulted in markedly ameliorated atherosclerosis, coupled with a significantly decreased VCAM-1 expression, though plasma lipids level remained comparable to that of HLD group. Regression analysis revealed a positive correlation between VCAM-1 expression and the extent of atherosclerosis (P<0.01). In addition, immunohistochemical analysis showed an increased activation of nuclear factor kappa B (NF-kB), a redox sensitive transcription factor essential for VCAM-1 expression, in aortas from rabbits fed on high lipid diet, which was evidently suppressed by crocetin supplementation. These findings suggest that the antiatherosclerotic effect of crocetin might be attributed, at least in part, to the suppressed expression of VCAM-1, which might result from reduced NF-kB activation. This study provides a further insight into the molecular mechanism by which antioxidants attenuate atherosclerosis and suggests a potential target for the treatment of atherosclerosis with antioxidants.

In the present study, we examined the prophylaxis effect of crocin on experimental atherosclerosis and it spossible mechanisms. The atherosclerosis formation was induced by hyperlipidamic diet in quails. At the 9th week, serum lipid, MDA and NO were measured, and HE staining was used to investigate the histopathological changes of aorta. Bovine aortic endothelial cells (EC) were obtained from the thoracic aorta of newborn calves. After incubation of the cells with Ox-LDL (50mg·L-1) for 24h, the activities of LDH, NO in culture media and activity of NOS in endothelial cells were measured, flow cytometer was used to determine the rate of endothelial cells apoptosis. Peritoneal macrophages were obtained from thioglycolate-injected mice. Cholesterol and free cholesterol in cells were assayed after incubation of the cells with Ox-LDL. Bovine aortic smooth muscle cells (SMC) were obtained from the thoracic aorta of newborn calf. Proliferation was induced by 100 Agd L 10X-LDL and antiproliferative effect of crocin on SMCs were observed. SMCs cycle phases were measured by flow cytometry. SMCs were loaded with Fluo-3/AM and [Ca2+]i was measured by Laser Scanning Confocal Microscope (LSCM). Crocin could reduce the level of serum TC, TG, LDL-C and inhibit the formation of aortic plaque. Crocin could reduce MDA and inhibit the descending of NO in serum. Compared with control, Ox-LDL group could increase the activity of LDH and decrease activity of NO in culture media and activity of NOS in endothelial cells, preincubated with crocin, the effects of Ox-LDL were inhibited. Crocin could decrease the EC apoptosis induced by Ox-LDL. Crocin concentration-dependently inhibited the TC and CE elevation induced by Ox-LDL in macrophages. Crocin could inhibit the proliferation of SMCs induced by Ox-LDL. In the presence or absence of extracellular Ca2+, crocin concentration-dependently inhibited the [Ca2+]i elevation induced by 120mgd L 1Ox-LDL, In the absence of extracellular Ca2+, crocin could inhibit the [Ca2+]i elevation induced by CHCl3 in a concentration-dependent manner. The results indicated that crocin could inhibit the formation of atherosclerosis in quails. Crocin had protective effects on endothelial cells. Crocin could decrease CE in macrophages and uptake of Ox-LDL, inhibiting the formation of foam cell, which would promote the initiation and progression of atherosclerosis. Crocin could inhibit the [Ca2+]i elevation in smooth muscle cell, Ca2+ is an important second messenger that regulates a variety of cellular processes, including smooth muscle cell proliferation and gene expression. Crocin exerted antiatherosclerotic effects through decreasing the level of Ox-LDL that plays an important role in the initiation and progression of atherosclerosis.

目的 研究西红花苷对血管平滑肌细胞内钙离子浓度的影响。方法 以Fluo-3/AM作为Ca2+荧光探针，采用激光扫描共聚焦显微镜观察牛主动脉平滑肌细胞内钙离子浓度的变化。结果 无论细胞外有无钙离子，西红花苷（1×10-8，1×10-7，1×10-6mol·L-1）均能明显抑制1×10-2mol·L-1 H202引起的细胞内钙离子浓度的升高，其抑制率含钙条件下分别为34.1%，57.1%和74.3%（P<0.01），无钙条件下分别为26.2%，32.1%和50.0%（P<0.01）；在胞外无钙的条件下，西红花苷（1×10-8，1×10-7，1×10-6mol·L-1）能抑制70 mmol·L-1 CHC13导致雷洛丁敏感钙池的释放，其抑制率分别为27.8%，27.8%和50.0%（P<0.01）。结论 西红花苷能抑制胞外钙离子的内流及内质网上钙离子的释放。

目的 研究西红花酸对压力超负荷所致大鼠心肌肥厚的影响。方法 腹主动脉部分狭窄术致心肌肥厚，采用试剂盒测定Na+-K+ ATPase和Ca2+-Mg2+ ATPase的活力及羟脯氨酸的含量，SDS-PAGE检测MMPs的活力。结果 模型组ATPase活性降低更加明显，羟脯氨酸的含量明显增加，MMPs活力明显增强。西红花酸能显著提高心肌组织的ATPase活力，降低胶原的含量，抑制MMPs的活力。结论 西红仡酸对斥力超负荷所致大鼠心肌肥厚具有一定的改善作用，抑制MMPs的活性可能是其作用机制之一。

目的 研究西红花酸对去甲肾上腺素（NE）诱导原代培养心肌细胞能量代谢障碍和细胞凋亡的保护作用。方法 1μmol·L-1 NE损伤原代培养的心肌细胞，检测细胞培养上清液的LDH、心肌细胞ATPase、线粒体琥珀酸脱氢酶（MSDH）的活力，线粒体膜电位的变化，流式细胞仪检测细胞凋亡，观察西红花酸保护作用。结果模型组细胞培养上清液LDH增加，心肌细胞MSDH和ATPase的活力降低，线粒体膜电位降低，心肌细胞凋亡率增加。西红花酸明显降低培养上清液LDH增加，提高MSDH和ATPase的活力、线粒体膜电位的水平，对心肌细胞的凋亡具有明显的保护作用。结论西红花酸对NE所致的心肌细胞能量代谢障碍和凋亡具有明显的保护作用。