甘草酸对载脂蛋白E基因敲除小鼠脂质代谢及动脉粥样硬化斑块的影响

Effects of Glycyrrhiza Acid on Lipid Metabolism and Atherosclerotic Lesions in Apolipoprotein E Gene Knockout Mice

目的探讨甘草酸对载脂蛋白E基因敲除(Apo E-/-)小鼠血脂代谢及动脉粥样硬化(As)斑块的影响及可能机制。方法雌性Apo E-/-小鼠18只,随机分为对照组和甘草酸组,高脂喂养12周中,甘草酸组给予甘草酸[100 mg/(kg·d)]灌胃,对照组给予等体积生理盐水灌胃,每4周监测小鼠体重并采取小鼠禁食后眼球后静脉血,酶法测量血脂、血糖水平及血清中对氧磷酶1(PON1)活性,小鼠安乐死后取主动脉窦部作冰冻切片油红O染色、胸腹主动脉段作剖面分析脂质斑块面积。实时荧光PCR检测肝组织中基因表达水平,Western blot检测肝组织中相关蛋白的表达水平。结果高脂喂养中小鼠体重增加、血脂紊乱加重。与对照组比较,甘草酸组小鼠体重增幅、血浆甘油三酯及血糖水平均无显著差异,但血清总胆固醇水平显著降低(P<0.05);与对照组比较,甘草酸降低主动脉窦及主动脉胸腹部斑块面积可达22%及21%(P<0.01和P<0.05)。实时荧光PCR结果显示甘草酸能显著上调肝脏脂质转运相关的B族Ⅰ型清道夫受体(SRBⅠ)及ATP结合盒转运体A1(ABCA1)的mRNA水平;其次,甘草酸可促进小鼠肝脏抗氧化酶PON1表达而升高血清中PON1活性(P<0.01),并显著提高肝细胞内甲硫氨酸亚砜还原酶A(Msr A)的表达水平显示其抗氧化能力。结论甘草酸能有效阻抑Apo E-/-小鼠As的发展,其机制可能涉及对肝脏胆固醇代谢调节及抗氧化功能的改善。

Aim To observe the effects and mechanism of glycyrrhiza acid( GA) on lipid metabolism and development of atherosclerotic lesions in apolipoprotein E gene knockout( Apo E-/-) mice. Methods Eighteen female Apo E-/-mice were randomly divided into control group and glycyrrhiza acid treatment group. All mice were fed with Western diet for 12 weeks,glycyrrhiza acid 100 mg /( kg·d) was intragastrically given to hyperlipidemic mice and 0. 9%Na Cl as the control. The weight of mice was detected per 4 weeks,the levels of plasma lipids and glucose were determined enzymatically,serum paraoxonase 1( PON1) activity was measured by using paraoxon as the substrate. The extent of aortic atherosclerosis was examined both in oil red O-stained cross-sections of the proximal aorta( 8 m cryosections) and by en face analysis with quantitation using Image J System. The expression levels of gene in liver were detected by realtime PCR and Western blot. Results The average weight of mice was increased and dyslipidemia was aggravated during being fed with Western diet. The increasing level of mice weight,the level of plasma triglycerides and glucose had no obvious change between both groups. However,the level of total cholesterol was statistically decreased( P < 0. 05) in Apo E-/-mice with glycyrrhiza acid treatment compared with control group. In mice of glycyrrhiza acid group,the atherosclerotic lesions of aortic root and aorta were reduced by 21% to 22% versus control mice. Glycyrrhiza acid obviously upregulated the mRNA level of scavenger receptor B Ⅰ( SR-B Ⅰ) and ATP-binding cassette transporter A1( ABCA1) in mouse liver. Meanwhile,glycyrrhiza acid significantly increased the serum antioxidative enzymes PON1 activity by upregulation of the PON1 expression level( P < 0. 01),and the expression level of cellular methionine sulfoxide reductase A( Msr A) was also increased. Conclusions Glycyrrhiza acid inhibits the development of the atherosclerosis,the mechanism might be related to the regulation of cholesterol metabolism and improvement of antioxidation.