Effects of Korean white ginseng extracts on obesity in high-fat diet-induced obese mice

Abstract

The present study examined the anti-obesity effect and mechanism of action of Korean white ginseng extracts (KGE) using high-fat diet (HFD)-induced obese mice. Mice were fed a low-fat diet (LFD), HFD or HFD containing 0.8 and 1.6% (w/w) KGE diet (HFD + 0.8KGE and HFD + 1.6KGE) for 8 weeks. We also examined the effects of KGE on plasma triglyceride (TG) elevation in mice administrated with oral lipid emulsion. Body weight gain and white adipose tissue (WAT) weight were significantly decreased in the HFD + 1.6KGE group, compared with the HFD group. The plasma TG levels were also significantly reduced in both HFD + 0.8KGE and HFD + 1.6KGE groups, while leptin levels were significantly decreased in only the HFD + 1.6KGE group, compared with the HFD group. The HFD + 1.6KGE group showed significantly lower mRNA levels of lipogenesis-related genes, including peroxisome proliferator-activated receptorγ2 (PPARγ2), sterol regulatory element binding protein-1c (SREBP-1c), lipoprotein lipase (LPL), fatty acid synthase (FAS) and diacylglycerol acyltransferase 1 (DGAT1), compared with the HFD group. In addition, a dose of 1000 mg/kg KGE inhibited the elevation of plasma TG levels compared with mice given the lipid emulsion alone. These results suggest that the anti-obesity effects of KGE may be elicited by regulating expression of lipogenesis-related genes in WAT and by delaying intestinal fat absorption.

Fig. 1

Effects of KGE on plasma adipokine levels in HFD-induced obese mice. Plasma adiponectin (a) and leptin (b) levels were measured from mice fasted for 16 h before collecting blood as described in the “Materials and methods” section. LFD: low-fat diet; HFD: high-fat diet; KGE: Korean white ginseng extracts. Data are expressed as mean ± SEM (n = 4–5/group). * p < 0.05 vs. LFD, ^# p < 0.05 vs. HFD

Fig. 2

Histology of epididymal adipose tissue of mice fed on experimental diet for 8 weeks. All sections were stained with hematoxylin and eosin; magnification, ×200

Fig. 3

Effect of KGE on mRNA levels of lipogenesis-related genes in WAT of HFD-induced obese mice. Mice were fed a LFD, HFD or HFD containing 0.8 and 1.6% (w/w) KGE for 8 weeks. a Relative mRNA levels of lipogenesis related genes were measured using a quantitative real-time RT–PCR as described in the “Materials and methods” section. The amount of mRNA was normalized to that of β-actin and expressed relative to the HFD group. b Protein levels of SREBP-1 and PPARγ2 were determined by western blot as described in the “Materials and methods” section. Protein level was expressed as the fold relative to the HFD group after normalized by β-actin level. LFD: low-fat diet; HFD: high-fat diet; KGE: Korean white ginseng extracts. Data are expressed as mean ± SEM (n = 4–5/group). * p < 0.05 vs. LFD, ^# p < 0.05 and ^## p < 0.01 vs. HFD

Fig. 4

Effect of KGE on plasma TG levels after an oral administration of lipid emulsion. After fasting 16 h, mice were orally administrated 0.5 mL of lipid emulsion with or without KGE. Plasma TG levels were measured as described in the “Materials and methods” section. Data are expressed as mean ± SEM (n = 8). * p < 0.05 vs. group treated with lipid emulsion