title: Effects of oolong tea on gene expression of gluconeogenic enzymes in the mouse liver and in rat hepatoma H4IIE cells.
abstract: Tea has many beneficial effects. We have previously reported that green tea and a catechin-rich green tea beverage modulated the gene expression of the gluconeogenic enzymes glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) in the normal murine liver. In the present study, we examined the effects of oral administration of oolong tea on the hepatic expression of gluconeogenesis-related genes in the mouse. The intake of oolong tea for 4 weeks reduced the hepatic expression of G6Pase and PEPCK together with that of the transcription factor hepatocyte nuclear factor (HNF) 4α. When rat hepatoma H4IIE cells were incubated in the presence of oolong tea, the expression of these genes was repressed in accordance with the findings in vivo. The reduced protein expression of PEPCK and HNF4α was also demonstrated. We then fractionated oolong tea by sequential extraction with three organic solvents to give three fractions and the residual fraction (Fraction IV). In addition to organic fractions, Fraction IV, which was devoid of low-molecular-weight catechins such as (-)-epigallocatechin gallate (EGCG), had effects similar to those of oolong tea on H4IIE cells. Fraction IV repressed the gene expression of insulin-like growth factor binding protein 1, as insulin did. This activity was different from that of EGCG. The present findings suggest that drinking oolong tea may help to prevent diabetes and that oolong tea contains a component or components with insulin-like activity distinguishable from EGCG. Identification of such component(s) may open the way to developing a new drug for diabetes.
authors.affiliation: Health Care Research Center, Nisshin Pharma Inc., Fujimino, Saitama, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Yasui
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Miyoshi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tababe
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ishigami
authors.forename: Ryuuta
authors.initials: R
authors.lastname: Fukutomi
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Imai
authors.forename: Mamoru
authors.initials: M
authors.lastname: Isemura
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000187:drug effects; D055808:Drug Discovery; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005943:Gluconeogenesis / Q000187:drug effects / Q000941:ethics; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000378:metabolism; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013662:Tea / Q000737:chemistry / Q000378:metabolism
chemical_list: D051557:Hepatocyte Nuclear Factor 4; C496593:Hnf4a protein, mouse; C496594:Hnf4a protein, rat; D007004:Hypoglycemic Agents; D018970:Insulin-Like Growth Factor Binding Protein 1; D010936:Plant Extracts; D012333:RNA, Messenger; D013662:Tea; D005952:Glucose-6-Phosphatase; D019764:Phosphoenolpyruvate Carboxykinase (ATP)