茜草水溶性提取物减少高脂饮食诱导的肥胖大鼠内脏脂肪

Rubia cordifolia L. aqueous extract reduces visceral fat mass of high fat diet-induced obese rats

目的探究传统中药茜草水溶性提取物(RCAE)对高脂饮食诱导的肥胖大鼠体质量、脂肪含量及糖脂代谢指标的影响及机制。方法构建含PPARγ2启动子序列的p GL3-Enhancer-PPARγ2(625 bp)-Luc荧光素酶报告基因表达质粒;建立稳定转染该质粒的3T3-L1前脂肪细胞系;用不同浓度(0.1 mg/L^1 000 mg/L)水提法提取的RCAE作用该细胞或用100 mg/L RCAE作用不同时间,检测PPARγ2启动子活性;用100 mg/L RCAE刺激人脂肪细胞并检测PPARγ2 mRNA表达;同时高脂饮食喂养大鼠,观察小和大剂量RCAE干预对血糖、血脂、胰岛素水平、体质量和内脏脂肪质量等的影响。结果 10 mg/L RCAE能促进3T3-L1细胞荧光素酶的表达,是对照组的1.43倍(P<0.01);当浓度达1 000 mg/L时,荧光素酶活性增加至对照组的3.24倍(P<0.01)。100 mg/L RCAE刺激3T3-L1细胞28 h,荧光素酶活性达最大值,是对照组的2.72倍(P<0.01);还能显著促进人脂肪细胞中PPARγ2 mRNA的表达,是对照组的2.27倍(P<0.01)。与高脂对照组相比,小剂量茜草组的空腹胰岛素水平及HOMA-IR显著降低,内脏脂肪质量明显减少(P<0.05)。结论小剂量RCAE能显著减轻高脂饮食诱导的肥胖大鼠的内脏脂肪质量和改善胰岛素抵抗。其作用机制可能与增强PPARγ2基因启动子活性和促进PPARγ2 mRNA表达有关。

Objective To evaluate the effects of a traditional Chinese medicine Rubia cordifolia L. aqueous extract （RCAE） on body weight, fat mass and parameters of glucose and lipid metabolism in high fat diet （HFD） -induced obese rats and its mechanism. Methods pGL3-Enhaneer-PPARγ2 （625 bp）-Luc plasmid, a luciferase reporter gene expression plasmid containing PPAR3,2 promoter was constructed and stably transfected 3T3-L1 preadipocytes were established. PPARγ2 promoter＇s activities in these cells were detected after administration with different con- centration （0. 1 mg/L- 1000 mg/L） of RCAE or with 100 mg/L RCAE for different action time. PPARγ2 mRNA expression in human adipocytes were detected after administration with 100 mg/L RCAE. Meanwhile, HFD-induced obese rats were administrated with low or high dose RCAE to investigate the effects of RCAE on serum glucose, lipid and insulin levels, body weight, visceral fat mass and so on. Results 10 mg/L RCAE could increase luciferase expression in 3T3-L1 cells to 1.43 folds of that in control group （P〈0. 01 ） and it reached 3.24 folds of that in control group when the concentration of RCAE was 1000 mg/L （P〈0.01）. With the administration with 100 mg/L RCAE, the luciferase activity of 3T3-L1 cells peaked at 28 h where it was 2.72 folds of that in control group （P〈 0. 01 ）, and the expression of PPARγ2 mRNA in human adipocytes increased to 2.27 folds of that in control group （P〈0. 01）. Compared with HFD group, low dose RCAE significantly reduced the fasting insulin level, HOMA-IR and visceral fat mass （ P 〈 0.05 ）. Conclusions Low dose RCAE significantly reduces the visceral fat mass and ameliorates insulin resistance in HFD-induced obese rats. The potential mechanism may be explained by the stimulation of PPARγ2 promoter activities and the increased expression of PPARγ2 gene.