Dietary green tea extract lowers plasma and hepatic triglycerides and decreases the expression of sterol regulatory element-binding protein-1c mRNA and its responsive genes in fructose-fed, ovariectomized rats.
The objective of this study was to determine whether green tea (GT) inhibits the expression of genes regulating hepatic lipogenesis and intestinal lipid transport in fructose-fed ovariectomized (OX) rats. OX rats were assigned to: 1) a control group (S) fed the AIN-93G diet with corn starch as the major carbohydrate source; 2) another control group (F) fed the same diet but containing fructose at 60% as the major carbohydrate source; 3) a group fed the F diet but containing 0.5% GT; and 4) a group fed the F diet containing 1% GT. At 6 wk, plasma and liver triglyceride (TG) and cholesterol and expression of liver sterol regulatory element-binding protein-1c (SREBP-1c) and selected genes involved in lipogenesis and lipid transport were measured. Fructose elevated plasma TG and cholesterol compared with the S group. GT at 0.5 and 1.0% markedly lowered plasma and liver TG. Fructose increased the expression of SREBP-1c, fatty acid synthase, and stearoyl-CoA desaturase 1 mRNA in the liver, whereas GT decreased the expression of these lipogenic genes. Similarly, fructose increased the abundance of hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase mRNA, whereas GT significantly decreased its expression. GT did not alter the expression of scavenger receptor class B, type 1, microsomal TG transfer protein, and apobec 1 in the liver and intestine. The results suggest that the lipid-lowering effect of GT is mediated partly by its inhibition of hepatic lipogenesis involving SREBP-1c and its responsive genes without affecting lipoprotein assembly.
Shrestha
Sudeep
S
Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
Ehlers
Sarah J
SJ
Lee
Ji-Young
JY
Fernandez
Maria-Luz
ML
Koo
Sung I
SI
D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003116:Color; D005260:Female; D005632:Fructose / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics / Q000378:metabolism*; D013662:Tea / Q000737:chemistry*; D014280:Triglycerides / Q000378:metabolism*
D001786:Blood Glucose; D012333:RNA, Messenger; D051780:Sterol Regulatory Element Binding Protein 1; D013662:Tea; D014280:Triglycerides; D005632:Fructose