高脂培养条件下槲皮素对大鼠肝细胞胆固醇代谢的影响

EFFECT OF QUERCETIN ON CHOLESTEROL METABOLISM IN RAT HEPATOCYTES CULTURED IN HIGH LIPID MEDIUM

目的探讨槲皮素对大鼠肝细胞胆固醇代谢的影响及相关机制。方法灌胃给予大鼠高脂乳剂1w,建立大鼠高脂血症模型,实验结束后,无菌条件下眼眶取血,离心取血清。采用含0、10μmol/L槲皮素的10%胎牛血清培养液干预培养BRL肝细胞24h,换液,用含0、10μmol/L槲皮素的10%高脂血清培养液干预培养BRL肝细胞48h,测定培养液中总胆固醇(total cholesterol,TC)、游离胆固醇(free cholesterol,FCH)、胆固醇酯(cholesterol ester,CE)、低密度脂蛋白胆固醇(low-density lipoprotein cholesterol,LDL-C),细胞内TC、FCH、CE的含量和调节胆固醇代谢的蛋白质,以及关键酶的表达与活性变化。结果与对照组相比较,10μmol/L槲皮素组培养液中TC、FCH和CE的浓度较低,且差异有统计学意义(P<0.05),槲皮素降低了LDL-C浓度,降低细胞内TC和FCH的浓度,升高细胞内CE含量,同时调节胆固醇代谢相应的酶和蛋白质,如羟甲基戊二酸单酰辅酶A还原酶(HMG-Co A Reductase,HMGCR)活性及其m RNA和蛋白质的表达水平较低,低密度脂蛋白受体(low-density lipoprotein receptor,LDLR)、胆固醇调节结合蛋白2(Sterol regulatory element-binding protein-2,SREBP-2)、三磷酸腺苷结合盒转运蛋白A1(ATP-binding cassette transporter A1,ABCA1)、肝X受体α(liver X receptorα,LXRα)m RNA和蛋白质的表达水平较高,且差异都具有统计学意义(P<0.05)。结论在高脂环境下,槲皮素可通过调节HMGCR、LDLR SREBP-2、ABCA1和LXRα的表达来调节胆固醇的代谢。

Objective To study the effect of quercetin on cholesterol metabolism in rat hepatocytes cultured in high lipid medium and explore possible mechanisms involved. Methods Rats were intragastrically given a high lipid emulsion for one week to induce hyperlipidemia. Blood samples were collected and hyperlipidemic serum was isolated by centrifugation. The rat hepatocytes were treated with different concentrations（0, 10μmol/L） of quercetin in 10% fetal bovine serum mediun for 24 h, and then switched to the media containing different concentrations（0, 10μmol/L） of quercetin and 10% hyperlipidemic serum for 48 h. The contents of extracellular total cholesterol（TC）, free cholesterol（FCH）, cholesterol ester（CE） and low-density lipoprotein cholesterol（LDL-C）, intracellular TC, FCH, CE and the expression of cholesterol metabolism related proteins and enzymes were assayed. Results In the quercetin group, the contents of extracellular TC, FCH and CE were significantly decreased compared with that of the control group（P0.05）. Meanwhile, the level of LDL-C, intracellular TC and FC were decreased, while the level of CE was increased after quercetin treatment. The m RNA and protein expression and activity of HMG-Co A reductase（HMGCR） was significantly decreased in the quercetin group compared with that of the control group, while the m RNA and protein expression of low-density lipoprotein receptor（LDLR）, Sterol regulatory element-binding protein-2（SREBP-2）, ATP-binding cassette transporter A1（ABCA1） and liver X receptorα（LXRα） were significantly increased（P0.05）. Conclusion In high lipid medium, quercetin can regulate cholesterol metabolism by modulating the expression of HMGCR, LDLR, SREBP-2, ABCA1 and LXRα in rat hepatocytes.