Download 2015 department of medicine research day

2015 DEPARTMENT OF MEDICINE RESEARCH DAY
Title of Poster: Effect of decaffeinated green and black tea extracts on energy
metabolism in mice fed a high fat/Western diet
Presenter: Susanne Henning
Division: Nutrition
☒Faculty ☐Fellow ☐Resident ☐Post-doc Research Fellow ☐Graduate Student ☐Medical Student ☐Other
Principal Investigator/Mentor: Zhaoping Li
Co-Investigators: Jieping Yang, Mark Hsu, David Heber
Thematic Poster Category: Nutrition, Digestion and Metabolism
Abstract
Background: Although green tea (GT) and black tea (BT) are chemically very different, both induce
a decrease in body weight and fat depots in male C57BL/6J mice fed high-fat /high-sucrose [HF/HS
(32% energy from fat; 25% energy from sucrose)] diets. While GT polyphenols are absorbed rapidly
in the small intestine, high molecular weight polyphenols from BT are not absorbed and reach the
large intestine. GT and BT consumption lead to alterations of the intestinal microflora.
Objective: This study investigated potential mechanisms such as short chain fatty acid (SCFA)
formation, gene expression of intestinal fatty acid transporters and tight junction (TJ) proteins and
hepatic gene expression of key enzymes in the energy metabolism and fat oxidation to elucidate how
decaffeinated polyphenol (P) extracts from GT and BT induce weight loss.
Design: 48 C57BL/6 male mice were randomly assigned to one of four treatment groups: control high
fat (HF)/high sucrose (HS)/Western diet (32% kcal from butter fat and corn oil, 25% kcal from
sucrose), or a HF/HS diet supplemented with either GT or BT extract providing 0.25% polyphenols or
a low fat diet (10.6% kcal from fat) for 4 weeks. Body fat composition was measured by weighing the
fat pads. Liver and intestinal tissue and content of ileum and cecum were collected. SCFA were
quantified using gas chromatography. Gene expression was determined using quantitative RT-PCR.
Results: All observations are in comparison to the high fat/high sucrose (HF/HS) fed control mice. GT
and BT administration decreased body weight and epidydimal, mesenteric and subcutaneous fat. Only
BT significantly increased propionic acid, i-butyric acid and induced a trend to increase for n-butyric
acid and the sum of SCFA in the cecum. GT and BT decreased gene expression of fatty acid
transporters in ileum tissue of fatty acid binding protein 2 (Fabp2) significantly and BT induced a trend
to decrease gene expression of fatty acid binding protein 4 (Fatp4) and cluster of differentiation/fatty
acid translocase (Cd36/Fat). Gene expression of the following hepatic key regulatory enzymes of fatty
acid β-oxidation was increased significantly by GT: Carnitine palmitoyl transferase 1 and 2 (Cpt1a,
Cpt1b, Cpt2) regulate transport of cytosolic fatty acids to mitochondria and long chain and very long
chain acetyl CoA dehydrogenase (Lcad, VLcad) catalyze the first step in FA β-oxidation in the
mitochondria. Proteins involved in intestinal tight junction (TJ) integrity such as transmembrane TJ
protein (occludin) and TJ-plague protein zonula occluden (ZO-1) were not altered significantly.
Conclusion: Although both GT and BT lower body weight and fat depots, only GT increased hepatic
energy metabolism by increasing fat oxidation directly by circulating GT polyphenols. BT polyphenols
act in the intestine by inhibiting fatty acid transport and increasing SCFA production by changes in the
microflora.