Effects of phytosterol content in vegetable oil on life span of salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP)

最近使用盐负载SHRSP的研究报告称，盐负载SHRSP根据饮食中植物油的类型而表现出不同的寿命。在本研究中，评估植物油中植物甾醇含量的差异是否会影响盐负荷SHRSP的卒中发病和寿命。雄性SHRSP/KPO在6周龄时使用。以含有不同含量植物甾醇的四种植物油为原料，配制试验日粮。在加速高血压的试验日粮中添加了3%的重量百分比的氯化钠。大鼠可以免费获得饮食和饮用水。血压测量采用尾脉冲拾取法。根据体重和食物摄入量的突然减少和特征性症状来判断卒中的发生，在卒中发作前，四个实验组的生长速度、食物摄入量没有显著差异。与…相比，米糠油组的收缩压有升高的趋势更多其他三个小组。无论植物油中的脂肪酸组成如何，植物油中植物甾醇的含量均以剂量依赖的方式缩短盐负载SHRSP的存活时间。接下来，为了阐明米糠油缩短存活时间的机制，我们重点研究了米糠油对盐负载SHRSP中风发病和脂代谢的影响。以米糠油或大豆油为脂肪源和3%氯化钠的饲料喂养大鼠38天，血清中胆固醇和磷脂水平显著高于对照组，这是由于高密度脂蛋白含量增加所致。非常重要的一点是要弄清楚为什么高密度脂蛋白分数增加，以及中风发病与高密度脂蛋白分数升高之间存在什么关系。在肝脏中，胆固醇和甘油三酯含量明显低于对照组。MRNA表达的比较研究表明，米糠油可抑制HMG-CoA还原酶，导致肝脏胆固醇含量降低。此外，激活PPAR(过氧化体增殖物激活受体)α靶基因可能导致肝脏甘油三酯含量降低。反之，肝X受体ABCG8mRNA表达降低可能导致α结合盒转运体G5和ABCG8mRNA表达降低，表明植物甾醇在肝脏中积累。这种植物甾醇在肝脏中的蓄积可能与米糠油的缩短存活时间密切相关。较少

Recent studies using salt-loaded SHRSP reported that salt-loaded SHRSP exhibited different lifespan depending on the type of vegetable oil in their diet. In the present study, to evaluate whether the difference of phytosterol content in vegetable oil influences stroke onset and lifespan of salt-loaded SHRSP. Male SHRSP/Kpo were used at the age of 6 weeks. Test diets were prepared by using four kinds of vegetable oils which contain different amount of phytosterol. Three percent NaCl by weight was added to the test diets for acceleration of hypertension. Rats had free access to the diet and drinking water. Blood pressure was measured by the tail-pulse pickup method. The onset of stroke was judged by sudden losses of both bodyweight and food intake and characteristic symptoms.There were no significant differences in growth rate, food intake among the four experimental groups before the onset of stroke. Systolic blood pressure of the ricebran oil group tended to be higher compared with the … More other three groups. Phytosterol content in the vegetable oil shortens survival time of salt-loaded SHRSP in a dose-dependent manner, regardless of fatty acids composition of the vegetable oil.Next, to elucidate the mechanism of survival time-shortening effect of ricebran oil, we focused on the effect of ricebran oil on stroke onset and lipid metabolism in salt-loaded SHRSP. Rats were fed the test diets containing ricebran oil or soybean oil (control) as fat source and 3% NaCl for 38 days.In the serum, cholesterol and phospholipids levels were significantly higher compared with the control, which was due to the increase in the HDL fraction. It will be very important to elucidate why the HDL fraction increases and what relationship exists between stroke onset and the elevation of the HDL fraction.In the liver, cholesterol and triglyceride contents were significantly lower compared with the control. A comparative study on mRNA expression indicated that ricebran oil may inhibit HMG-CoA reductase, resulting in the reduction of hepatic cholesterol content. In addition, activation of PPAR (peroxisome proliferators-activeted receptor)α target genes may induce the reduction of hepatic triglyceride content. Conversely, reduction of LXR (liver X-receptor)α mRNA expression may induce the reduction of ABC (ATP-binding cassette transporter) G5 and ABCG8 mRNA expressions, which indicates accumulation of phytosterol in the liver. This hepatic accumulation of phytosterol might be closely related to the survival time-shortening effect of ricebran oil. Less