title: Green tea extract suppresses adiposity and affects the expression of lipid metabolism genes in diet-induced obese zebrafish.
abstract: BACKGROUND
  Visceral fat accumulation is one of the most important predictors of mortality in obese populations. Administration of green tea extract (GTE) can reduce body fat and reduce the risk of obesity-related diseases in mammals. In this study, we investigated the effects and mechanisms of GTE on adiposity in diet-induced obese (DIO) zebrafish.
  
  
  METHODS
  Zebrafish at 3.5 to 4.5 months post-fertilization were allocated to four groups: non-DIO, DIO, DIO + 0.0025%GTE, and DIO + 0.0050%GTE. The non-DIO group was fed freshly hatched Artemia once daily (5 mg cysts/fish daily) for 40 days. Zebrafish in the three DIO groups were fed freshly hatched Artemia three times daily (60 mg cysts/fish daily). Zebrafish in the DIO + 0.0025%GTE and DIO + 0.0050%GTE groups were exposed to GTE after the start of feeding three times daily for 40 days.
  
  
  RESULTS
  Three-dimensional microcomputed tomography analysis showed that GTE exposure significantly decreased the volume of visceral but not subcutaneous fat tissue in DIO zebrafish. GTE exposure increased hepatic expression of the lipid catabolism genes ACOX1 (acyl-coenzyme A oxidase 1, palmitoyl), ACADM (acyl-coenzyme A dehydrogenase, c-4 to c-12 straight chain), and PPARA (peroxisome proliferator-activated receptor alpha). GTE exposure also significantly decreased the visceral fat expression of SOCS3 (suppressor of cytokine signaling 3b) which inhibits leptin signaling.
  
  
  CONCLUSIONS
  The present results are consistent with those seen in mammals treated with GTE, supporting the validity of studying the effects of GTE in DIO zebrafish. Our results suggest that GTE exerts beneficial effects on adiposity, possibly by altering the expression of lipid catabolism genes and SOCS3.
authors.affiliation: Department of Molecular and Cellular Pharmacology, Pharmacogenomics and Pharmacoinformatics, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan. tanaka@doc.medic.mie-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hasumura
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Shimada
authors.forename: Junya
authors.initials: J
authors.lastname: Kuroyanagi
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Shinichi
authors.initials: S
authors.lastname: Meguro
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takema
authors.forename: Toshio
authors.initials: T
authors.lastname: Tanaka