Studies On Regulation Of Dark Tea On Lipid Metabolism

Hyperlipidemia is playing a greatly important role in the development of metabolic diseases such as atherosclerotic lesion, coronary artery, diabetes and obesity. Recently, much attention has been paid to tea and its various active components which might have effective functions for the prevention of atherosclerosis and amelioration of lipid metabolism, but yet little is known about hypolipidemic mechanisms. Therefore, Dark tea, as a peculiar kind of tea product belonging to China,which also has many origins and varieties of designs, is expected to be further studied on its lipid-lowering effect and related mechanisms.Studies on effects of six Dark tea, that is puerh, Fuzhuan, Liubao, Jinjian, Qingzhuan and Mizhuan, on lipid metabolism in the paper were performed through both in vivo animal experiment and in vitro cell systems.1Lipid-lowering effects of six dark tea on the hyperlipidemia ratsIn the paper, through the establishment of hyperlipidemia rats model, we studied the lipid-lowering effects of six dark tea water extract by investigating a series of indexes such as changes of food intake per week and growth of body weights in each group, serum lipid level, observation of the pathological damage of liver, expression level of genes related to lipid metabolism in rat livers.The results showed that:(1)During the whole experimental period, changes of food intake of rats in each group showed the same trend, suggesting no significant differences in food intake between groups; Compared with the modeling group, growth of body weights in six tea groups appeared a slowdown speed.(2)Compared with the modeling group, the total TC and TG levels in six dark tea high-dosage groups significantly decreased; except Mizhuan group, the other dark tea high-dosage groups had the increasing level of HDL-C; Puerh and Fuzhuan high-dosage group showed the remarkably decreasing level of LDL-C, yet that of the other tea high-dosage groups had no marked change.(3)Except Mizhuan, the other dark tea of high-dosage could effectively protect the liver from damages caused by intake of high-fat food, and also effectively ameliorate hepatic fatty degeneration. Especially, Fuzhuan, Puerh and Qingzhuan exhibited the good results in this respect.(4)Expression of genes (ACAT1, ADRP, DGAT1and DGAT2) related to lipid metabolism were partly inhibited by Fuzhuan and Qingzhuan, resulting in the decreasing TC levels in serum and lipid deposition in livers. Expression level of LCAT mRNA showed no significant change.2Lipid-lowering effects of six dark tea in HepG2cellHepG2cell, cultured in DMEM medium containing25Mm glucose, were then exposed in six dark tea at different concentrations. The cell viability, TG level and expression level of genes (AMPKa-2、ACC1、CHREBP、HL、SREBP-1c) related to lipid metabolism in HepG2cells were investigated, demonstrating the Lipid-lowering effects of dark tea in cell level.The results showed that:(1)With the growing concentrations of100～1000μg/mL, six Dark tea showed certain increasing inhibitions to the proliferation of HepG2cells. Six Dark tea had slight inhibitons to cell growth at the concentration of200μg/mL, and except Puerh and Fuzhuan tea, others showed remarkable inhibitons at the concentration of500μg/mL.(2)At the concentration of500μg/mL, TG content in HepG2cells deceased, indicating the lipid-lowering effect of the dark tea.(3)At the concentration of500μg/mL, six Dark tea had impacts on the expressions of genes related to lipid metabolism (AMPKa-2、ACC1、CHREBP、HL、 SREBP-1c) in HepG2cells.(4)Apart from Fuzhuan and Jinjian tea, other dark tea increased the expression level of AMPKa-2mRNA; Apart from Fuzhuan and Liubao, other dark tea increased the expression level of HL mRNA. Apart from Puerh and Jinjian tea, other dark tea decreased the expression level of ACC1and CHREBP mRNA; Apart from Puerh tea, other dark tea decreased the expression level of SREBP1-c mRNA.