Combined Ingestion of Tea Catechin and Citrus β-Cryptoxanthin Improves Liver Function via Adipokines in Chronic Obesity

Abstract

Recently, there has been an increase in the number of obese individuals, which has elevated the risk of related diseases. Although several studies have been performed to develop a definitive treatment for obesity, no solution has yet been achieved. Recent evidence suggests that tea catechins possess antiobesity effects; however, an impractical amount of catechin may be required to achieve antiobesity effects in humans. Moreover, studies are yet to elucidate the effects of the combined treatment of tea catechins with other substances. Here, we investigated the synergistic effects of catechins and β-cryptoxanthin in high-calorie diet-induced mice. Combined treatment with catechins and β-cryptoxanthin significantly suppressed obesity-induced weight gain and adipocyte size and area, restoring serum parameters to normal. Additionally, combined treatment with catechins and β-cryptoxanthin suppressed inflammatory responses in adipocytes, restored adiponectin levels to normal, protected the liver against obesity-induced damage, and restored normal liver function. Moreover, activin E level was restored to normal, possibly affecting the energy metabolism of brown adipocytes. Overall, these results suggest that the combined ingestion of tea catechins and β-cryptoxanthin was not only effective against obesity but may also help to prevent obesity-related diseases, such as diabetes and cardiovascular diseases.

Keywords: activin E; adipokines; catechin; flavonoid; green tea; high-calorie; obesity; polyphenol; β-carotene; β-cryptoxanthin.

Figure 1

(A) Photo of mice (15 weeks of age) in each group. (B) Average body weight (15 weeks of age) of mice in each group. Average daily (C) feed intake and (D) water intake (15 weeks of age) in each group. Data are presented as mean ± standard deviation (SD); * p < 0.05 compared to control animals.

Figure 2

Changes in the body weight (11–15 weeks of age) of mice in each group. Cont, HC, HC + G, HC + β, and HC + G + β indicate the control, high-calorie-fed, high-calorie-fed + green-tea-intake, high-calorie-fed + β-cryptoxanthin-intake, and high-calorie-fed + green tea + β-cryptoxanthin-intake groups, respectively. Data are presented as mean ± standard deviation; * p < 0.05 compared to the control group, and ^# p < 0.05 compared to high-calorie-fed group.

Figure 3

Blood chemistry of mice in the different groups. (A) Blood glucose, (B) total protein, (C) total lipid, (D) low-density lipoprotein (LDL) cholesterol, (E) high-density lipoprotein (HDL) cholesterol, (F) free cholesterol, (G) free fatty acid (non-esterified fatty acid, NEFA), and (H) triglyceride (TG, neutral fat). Cont, HC, HC + G, HC + β, and HC + G + β indicate control, high-calorie-fed, high-calorie-fed + green-tea-intake, high-calorie-fed + β-cryptoxanthin-intake, and high-calorie-fed + green tea + β-cryptoxanthin-intake groups, respectively. Data are presented as mean ± standard deviation; * p < 0.05 compared to the control group, and ^# p < 0.05 compared to high-calorie-fed group.

Figure 4

Hematoxylin–eosin (HE) staining of white adipocytes in the abdomen. (A) Adipocytes of mice in the control group, (B) adipocytes of mice in the high-calorie-fed group, (C) adipocytes of mice in the high-calorie-fed + green tea + β-cryptoxanthin-intake group. Scale bar is in C = 50 μm. (D) Average area of adipocytes. (E) Variation in the size of adipocytes. Cont, HC, and HC + G + β indicate the control, high-calorie-fed, and high-calorie-fed + green tea + β-cryptoxanthin-intake groups, respectively. Data are shown as mean ± standard deviation; * p < 0.05 compared to the control group, and ^# p < 0.05 compared to high-calorie-fed group.

Figure 5

Quantitative analysis of inflammatory cytokines in adipose tissue using ELISA. (A) TNF-α, (B) IL-1β, (C) IL-6, (D) arginase 1 (ARG1), (E) IL-10, and (F) adiponectin. Cont, HC, HC + G, HC + β, and HC + G + β indicate the control, high-calorie-fed, high-calorie-fed + green-tea-intake, high-calorie-fed + β-cryptoxanthin-intake, and high-calorie-fed + green tea + β-cryptoxanthin-intake groups, respectively. Data are shown as mean ± standard deviation; * p < 0.05 compared to the control group, and ^# p < 0.05 compared to high-calorie-fed group.

Figure 6

(A–C) Liver stained with adiponectin receptor, (D–F) liver stained with hematoxylin–eosin (HE), and (G–I) liver stained with Oil-Red-O. (A,D,G) Hepatocytes in the control group, (B,E,H) hepatocytes in the high-calorie-fed (HC) group, (C,F,I) hepatocytes in the high-calorie-fed + green tea + β-cryptoxanthin-intake (HC + G + β) group. Scale bar is in C = 100 μm.

Figure 7

Serum levels of (A) alkaline phosphatase (ALP), (B) aspartate aminotransferase (AST), and (C) alanine aminotransferase (ALT). Cont, HC, HC + G, HC + β, and HC + G + β indicate the control, high-calorie-fed, high-calorie-fed + green-tea-intake, high-calorie-fed + β-cryptoxanthin-intake, and high-calorie-fed + green tea + β-cryptoxanthin-intake groups, respectively. Data are shown as mean ± standard deviation; * p < 0.05 compared to control animals, and ^# p < 0.05 compared to HC.

Figure 8

Photographs of liver stained with activin E ((A–C): low magnification views; (A′–C′): high magnification views). (A,A′) Hepatocytes of mice in the control group, (B,B′) hepatocytes of mice in the high-calorie-fed (HC) group, (C,C′) hepatocytes of mice in the high-calorie-fed + green tea + β-cryptoxanthin-intake (HC + G + β) group. Scale bar is in C = 100 μm.