1,25-二羟基维生素D3在蛋氨酸胆碱缺乏饮食诱导的大鼠肝脏脂质代谢中的作用

Role of 1,25-dihydroxyvitamin D3 in liver lipid metabolism induced by methionine-choline-deficient diet in rats

目的探讨1,25-二羟基维生素D3[1.25(OH)2D3]在肝脏脂质代谢中的作用,为阐明非酒精性脂肪肝发生的机制提供线索。方法将26只SD大鼠随机分为对照组(蛋氨酸胆碱充足饮食,MCS)、模型组(蛋氨酸胆碱缺乏饮食,MCD)和干预组[MCD+1.25(OH)2D3],干预组每天按体质量给予3 ng/100 g的1.25(OH)2D3花生油溶液灌胃,对照组及模型组给予等体积花生油灌胃。4周后实验结束,下腔静脉取血检测丙氨酸转氨酶(ALT)和天冬氨酸转氨酶(AST),留取肝组织观察肝脏形态和病理改变(油红O及HE染色),并检测肝脏总甘油三酯(TG)含量以及肝脏脂质代谢相关基因[脂肪酸转运蛋白36(FAT/CD36)、乙酰辅酶A羧化酶(ACC1)]mRNA及其蛋白水平。组间均数比较采用单因素方差分析。结果油红O染色及HE染色均可见模型组大鼠肝组织大量脂滴空泡,干预组明显减轻。干预组肝脏TG含量(2.23±0.98)μmol/g较模型组(3.53±1.06)μmol/g明显降低(F=5.930,P=0.035)。干预组ALT含量(35.99±9.54)U/L较模型组ALT含量(57.65±19.42)U/L显著下降(F=13.790,P=0.034);干预组AST含量(16.9±3.73)U/L较模型组AST含量(27.81±13.31)U/L显著下降(F=3.084,P=0.046)。干预组大鼠FAT/CD36的mRNA和蛋白相对表达水平(mRNA:1.21±0.61,蛋白:1.54±0.75)较模型组表达水平(mRNA:2.31±0.81,蛋白:2.83±1.42)显著降低(mRNA:F=8.370,P=0.001;蛋白:F=7.212,P=0.043);同样,ACC1的mRNA和蛋白相对表达水平(mRNA:0.89±0.54,蛋白:0.28±0.11)较模型组表达水平(mRNA:1.39±0.19,蛋白:0.47±0.24)显著降低(mRNA:F=3.948,P=0.036;蛋白:F=10.933,P=0.048)。结论1.25(OH)2D3减轻了MCD饮食大鼠的肝脏脂肪沉积,这可能通过抑制FAT/CD36以及ACC1的表达来实现。

Objective To investigate the role of 1,25-dihydroxyvitamin D3[1.25(OH)2D3]in liver lipid metabolism so as to provide the clues for elucidating the mechanism of non-alcoholic fatty liver.Methods 26 SD rats were randomly divided into control group(methionine-choline-sufficient diet,MCS),model group(methionine-choline-deficiency diet,MCD)and intervention group[MCD+1.25(OH)2D3].The intervention,control,and model group was given 3 ng/100 g 1.25(OH)2D3 peanut oil solution per day by gavage according to body mass.After 4 weeks the experiment was ended up,and the blood was collected from the inferior vena cava to detect alanine aminotransferase(ALT)and aspartate aminotransferase(AST).The liver tissue was collected to observe the liver morphological and pathological changes(oil red O and HE staining).The changes in the level of liver total triglyceride(TG)content and liver lipid metabolism-related genes[fatty acid transfer protein(FAT/CD36),acetyl-coenzyme A carboxylase(ACC1)]mRNA and protein were detected.One-way analysis of variance was used to compare the means between groups.Results Oil red O staining and HE staining showed that lipid droplet-vacuoles were significantly increased in the liver tissue of the model group than that of the intervention group.The liver TG content(2.23±0.98)μmol/g of the intervention group was significantly lower than that of the model group(3.53±1.06)μmol/g(F=5.930,P=0.035).The ALT content of the intervention group(35.99±9.54)U/L was significantly lower than that of the model group(57.65±19.42)U/L(F=13.790,P=0.034).The AST content of the intervention group(16.9±3.73)U/L was significantly lower than that of the model group(27.81±13.31)U/L(F=3.084,P=0.046).The relative expression levels of mRNA and protein(mRNA:1.21±0.61,protein:1.54±0.75)of FAT/CD36 in the intervention group were significantly lower than those of the model group(mRNA:2.31±0.81,protein:2.83±1.42)(mRNA:F=8.370,P=0.001,protein:F=7.212,P=0.043).The relative expression level of mRNA and protein of ACC1(mRNA:0.89±0.54,protein:0.28±0.11)were also significantly lower than those in model group(mRNA:1.39±0.19,protein:0.47±0.24)(mRNA:F=3.948,P=0.036,protein:F=10.933,P=0.048).Conclusion 1.25(OH)2D3 can reduce liver fat deposition in rats fed with MCD by inhibiting the expression of fat/CD36 and ACC1.