Green tea polyphenols ameliorate non-alcoholic fatty liver disease through upregulating AMPK activation in high fat fed Zucker fatty rats

Figure 1 Effect of green tea polyphenols on alanine transaminase (A) and aspartate transaminase (B) in high-fat diet Zucker fatty rats. Serum alanine transaminase (ALT) and aspartate transaminase (AST) concentrations were measured after 8 wk of daily treatment with saline (5 mL/kg; Lean, ZF-Con) or GTP (200 mg/kg; ZF-GTP). Data are means ± SEM, n = 12 rats/group. ^bP < 0.01 vs Lean rats and ^dP < 0.01 vs ZF-Con rats.

Figure 2 Reduction of hepatic steatosis and triglyceride content with green tea polyphenols treatment. A: Images were stained with H&E to visualise macrovesicular steatosis in liver sections at × 400 magnification. Compared to the livers in lean control rats, a larger unstained area that consisted of fat vacuoles was seen in ZF control rats; B: Representative ORO staining of liver samples from lean, ZF-Con and ZF-GTP rats. A larger red area that consisted of lipid droplets (B, C: ORO staining; × 400 magnification) and higher triglyceride contents (D) in the livers of ZF-control rats. GTP treatment significantly reversed these changes in the liver. Data are expressed as mean ± SME from 6-8 rats each group. ^bP < 0.01, ^eP < 0.001 vs Lean group; ^dP < 0.01 vs ZF-Con group. GTP: Green tea polyphenols; ZF: Zucker fatty.

Figure 3 Effects of green tea polyphenols on inflammatory cytokines in circulation. TNF-α (A), IL-6 (B), IL-10 (C) and IFNγ (D) levels in serum of lean, ZF-Con and ZF-GTP rats. Data are mean ± SEM from 12 rats each group. ^aP < 0.05 , ^bP < 0.01 vs lean group; ^cP < 0.05 vs ZF-Con group. GTP: Green tea polyphenols; ZF: Zucker fatty.

Figure 4 Effects of green tea polyphenols on de novo lipogenesis pathway in the liver of Zucker fatty rats. Proteins extracted from the livers of lean, Zucker fatty (ZF)-Con. and ZF-GTP rats were separated by SDS-PAGE and immunoblotted with anti-p-AMPK-α, anti-AMPK-α, and anti-p-ACC: Anti-ACC. β-Actin was used to confirm equal protein loading. Upper panels (A and C): Immunoblot bands of detected proteins; lower panels (B and D): Quantitative analysis of corresponding proteins. Data are expressed as mean ± SME (n = 8). ^aP < 0.05 vs lean, ^cP < 0.05 vs ZF-Con. GTP: Green tea polyphenols; ACC: Acetyl-CoA carboxylase.

Figure 5 Expression of SREBP-1c in the liver of Zucker fatty rats. Immunoblots (A) and quantitative analysis of (B) SREBP-1c in liver tissue of chow fed lean rats and HFD fed Zucker fatty (ZF) rats treated with saline (5 mL/kg of body weight) or with GTP (200 mg/kg of body weight). β-Actin was used to confirm equal protein loading. Data are expressed as mean ± SME (n = 8). ^bP < 0.01 vs lean, ^dP < 0.01 vs ZF-Con. GTP: Green tea polyphenols.