A Single Oral Administration of Theaflavins Increases Energy Expenditure and the Expression of Metabolic Genes

Abstract

Theaflavins are polyphenols found in black tea, whose physiological activities are not well understood. This study on mice evaluated the influence of a single oral administration of theaflavins on energy metabolism by monitoring the initial metabolic changess in skeletal muscle and brown adipose tissue (BAT). Oxygen consumption (VO2) and energy expenditure (EE) were increased significantly in mice treated with theaflavin rich fraction (TF) compared with the group administered vehicle alone. There was no difference in locomotor activity. Fasting mice were euthanized under anesthesia before and 2 and 5, 20-hr after treatment with TF or vehicle. The mRNA levels of uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in BAT were increased significantly 2-hr after administration ofTF. The levels of UCP-3 and PGC-1α in the gastrocnemius muscle were increased significantly 2 and 5-hr after administration of TF. The concentration of phosphorylated AMP-activated protein kinase (AMPK) 1α was also increased significantly in the gastrocnemius 2 and 5-hr after treatment with TF. These results indicate that TF significantly enhances systemic energy expenditure, as evidenced by an increase in expression of metabolic genes.

Fig 1. Oxygen consumption (VO₂₎ and energy expenditure (EE) 20 hr after administration of theaflavin.

The respiratory exchange ratio (RER) was calculated using VO₂ and carbon dioxide excretion (VCO₂) and the Weir equation. Total VO₂ and EE during the light (12:00–18:00 and 6:00–8:00) or dark (18:00–6:00) cycles are shown in b and d. The locomotor activity of the animals 20 hr after administration of vehicle or theaflavin is shown in e, while locomotor activity of the mice during the total, light or dark cycles is shown in f. The mice were administrated either vehicle (n = 8) or 10 mg/kg theaflavin (n = 8). The values represent the mean ± standard deviation. The statistical analyses were performed two way ANCOVA (a,c,e) post hoc comparisons with the vehicle group were made by the two-tailed followed by Dunnett's test. Significantly different from vehicle, *p<0.05.

Fig 2. Expression of mRNA for UCP-1 in BAT (a) and UCP-3 in gastrocnemius muscle (b) after administration of vehicle or theaflavin.

The animals were euthanized before and 2, 5, and 20 hr after administration of vehicle or 10 mg/kg theaflavin (n = 8). The values represent the mean ± standard deviation. The statistical analyses were performed two way ANCOVA post hoc comparisons with the vehicle group were made by the two-tailed followed by Dunnett's test. Significantly different from vehicle, *p<0.05, **p<0.01.

Fig 3. Expression of mRNA for PGC1-α in BAT (a) or gastrocnemius (b) after administration of vehicle or theaflavin.

The animals were euthanized before and 2, 5, and 20 hr after administration of vehicle (n = 8) or 10 mg/kg theaflavin (n = 8). The values represent the mean ± standard deviation. The statistical analyses were performed two way ANCOVA, post hoc comparisons with the vehicle group were made by the two-tailed followed by Dunnett's test. Significantly different from vehicle, *p<0.05.

Fig 4. Phosphorylation of AMPK1α in gastrocnemius muscle after administration of vehicle or theaflavin.

The animals was euthanized before and 2, 5, and 20 hr after administration of the vehicle (n = 8) or 10 mg/kg theaflavin (n = 8). The values represent the mean ± standard deviation. The statistical analyses were performed two way ANCOVA, post hoc comparisons with the vehicle group were made by the two-tailed followed by Dunnett's test. Significantly different from vehicle, **p<0.01.